Southern Ontario Bald Eagle Monitoring Project · Eagle deaths ... food pad length, hallux claw...

Bird Studies Canada / Études D’Oiseaux Canada P.O. Box/B.P. 160, 115 Front St., Port Rowan, ON Canada N0E 1M0 www.bsc-eoc.org

EnvironmentCanada

Ontario Region

EnvironnementCanada

Région de l’Ontario

Southern Ontario Bald Eagle Monitoring Project

2004 Final Report

Juvenile Bald Eagles in nest. Photo: Marc Bacro

January 2005

Dawn K. Laing

and

Debbie S. Badzinski

Edwards Charitable Foundation

2004 Southern Ontario Bald Eagle Monitoring Project

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TABLE OF CONTENTS

Introduction ............................................................................................................................................3 Methods ..................................................................................................................................................4 Nest monitoring ......................................................................................................................................4 Accessing nests.......................................................................................................................................4 Morphological measurements ................................................................................................................5 Banding...................................................................................................................................................5 Blood sampling.......................................................................................................................................5 Feather sampling ....................................................................................................................................6 Transmitter attachment ...........................................................................................................................6 Returning nestlings to the nest ...............................................................................................................7 Tracking and data analysis .....................................................................................................................7 Terminology ...........................................................................................................................................7 Results ....................................................................................................................................................8 Update on territories that were new in 2003 ..........................................................................................8 New territories in 2004...........................................................................................................................8 Nesting activity.......................................................................................................................................9 Nest failure and attrition.........................................................................................................................9 Productivity ..........................................................................................................................................10 Banding and Blood Sampling...............................................................................................................10 Satellite telemetry................................................................................................................................10 Eagle deaths..........................................................................................................................................11 Discussion.............................................................................................................................................18 Conclusion............................................................................................................................................20 Recommendations ................................................................................................................................20 Literature Cited.....................................................................................................................................22

LIST OF FIGURES

FIGURE 1 - The number of successful Bald Eagle nests in Southern Ontario, and the total number of eaglets produced from 1980-2004. FIGURE 2 - Productivity (mean number of chicks fledged per active nest) of Bald Eagles in Southern Ontario between 1980 and 2004. FIGURE 3 - Satellite movements of juvenile eagles.

LIST OF TABLES

TABLE 1 - Summary of Bald Eagle nesting activity and productivity at each territory in Southern Ontario in 2004. TABLE 2 – Additional Bald Eagle activity reported during the 2004 breeding season. TABLE 3 - Summary of Bald Eagle nesting activity in Southern Ontario in 2004. TABLE 4 – Banding efforts for southern Ontario Bald Eagle monitoring program 2004. APPENDIX A - Southern Ontario Bald Eaglet production by nest, 1980-2004.


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INTRODUCTION Prior to European settlement, the Great Lakes supported a healthy population of Bald Eagles (Haliaeetus leucocephalus). An estimated 200 pairs nested from the Ottawa River to the lower Great Lakes, and the density of Bald Eagle nests (active and inactive) may have reached as high as one per mile of shoreline along Lake Erie (Weekes 1974). However, loss of nesting and foraging habitat through the clearing of land for agriculture, along with direct human persecution, led to a rapid decline in the Great Lakes Bald Eagle population in the early 1900s (reviewed in Austen et al. 1994). The introduction of protective legislation, including the Ontario Ministry of Natural Resources’ Game and Fish Act in 1890, and the American Bald Eagle Act in 1940 helped the southern Ontario eagle population rebound to approximately 100 pairs by 1950 (Weekes 1974). Unfortunately, this recovery was short-lived, due to the introduction of synthetic chlorinated compounds such as DDT and PCBs into the Great Lakes aquatic food chain. Bioaccumulation of DDT (and its breakdown product DDE) in the bodies of adult Bald Eagles led to reproductive failure through eggshell thinning and embryo death (Donaldson et al. 1999). The Bald Eagle population in the Great Lakes basin declined almost to the point of extirpation in the 1960s (reviewed in Donaldson et al. 1999). Although Canada and the US severely restricted the use of DDT in the 1970s, the effects lingered on for many more years. Bald Eagles in the Great Lakes were slow to recover, possibly due to continued exposure to PCBs (Donaldson et al. 1999). In 1980, the Great Lakes Bald Eagle population experienced almost complete reproductive failure. There were only three active nests along the north shore of Lake Erie in that year, and all failed to produce young (OMNR historical data). To begin to address the problems facing this species, the Bald Eagle was declared a provincially Endangered Species in 1973 and the Ontario Ministry of Natural Resources (OMNR) began to closely monitor the population. In 1983, the Southern Ontario Bald Eagle Monitoring Project, a cooperative project led by the OMNR and the Canadian Wildlife Service (CWS) was initiated. Population monitoring was led by OMNR and the hacking of young eaglets was led by CWS. Bird Studies Canada (BSC) became a partner in the Bald Eagle monitoring project in 1996, when it assumed responsibility for the coordination of field studies and monitoring efforts. This project relies heavily on the cooperation of landowners and volunteer nest monitors to obtain information on Bald Eagle nesting activity and productivity. The study area includes the Canadian shores of lakes Erie, St. Clair, Huron and Ontario. From 1973-1982, OMNR (with assistance from the public) monitored territories, productivity (number of young fledged per active nest), and mortality. Beginning in 1983, productivity was monitored annually from the nest, and eaglets within the study area were weighed, measured, and banded. Nest site characteristics, such as tree species and height of nest were also recorded. To further aid recovery efforts, from 1983-1987, 32 eaglets were transplanted from northwestern Ontario and released at two hacking sites on the north shore of Lake Erie. From 1988-1999, blood and feather samples were taken from eaglets to monitor levels of pesticides and heavy metal contaminants. Analysis of data collected from these field studies showed that, by the early 1990s, the health of the Bald Eagle population had improved and levels of contaminants had


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declined dramatically. At the same time, the number of nests and the mean number of chicks produced at each nest had also increased. Starting in 2000, a low-intensity monitoring protocol based on annual ground and aerial observations of nesting eagles was implemented. Annual blood samples were no longer deemed necessary, since there was fairly strong evidence for a decline in contaminants in Great Lakes eagles (Donaldson et al.1999), and all eaglets hatched over the last decade and examined appeared to be healthy (P. Hunter pers. comm.). Blood sampling and banding now occurs at five-year intervals, which should be adequate to monitor contaminant levels in juvenile birds. The objectives of the 2004 project were to:

1. Locate and monitor all territories (new and historic) in southern Ontario through a network of volunteer nest monitors and landowners, in order to continue to provide accurate information on eagle population size and productivity;

2. Sample eaglet blood and feathers from a subset of nests for contaminants analyses; 3. Colour band eaglets to provide information on dispersal and longevity; and 4. Use satellite telemetry to track movements of three young eagles for approximately 3 to 5

years, in order to determine dispersal patterns and identify potential regions where they may be exposed to contaminants (particularly heavy metals).

METHODS

NEST MONITORING Volunteers began monitoring Bald Eagle activity as soon as the birds returned to their territories. In some cases, pairs remained on territory year round, whereas at other locations the birds returned between January and February. In April, volunteer nest monitors were contacted to determine nesting status at each established territory. Established territories were defined as areas where eagles have nested on at least one occasion from 1980-2003. All reports of new territories and their respective nests were verified, landowners were contacted, and nest monitors were established. At each active nest, monitors were asked to observe the nest without disturbing the eagles, and to note the number of young visible. Further contact was made throughout June to determine productivity at each nest. Young that reached 8-10 weeks, or were observed out of the nest, were considered successfully fledged. Productivity was calculated as the number of young fledged/active nest. In 2004, majority of Bald Eagle nests were monitored from the ground, with the exception of the southwestern basin of Lake Erie which was also surveyed from the air (Courtesy: P. Roberts). ACCESSING NESTS Prior to any fieldwork, landowners were contacted in order to gain permission for the field team to access nest sites. Nests were accessed only when the young appeared to be 9-10 weeks old. Most were handled at 64 days of age. This age range ensures that the bird is of sufficient size for


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banding, blood sampling and transmitter attachment but young enough to prevent pre-mature fledging from the nest. Nests were not accessed under weather conditions that would have put the eagles or staff in danger (i.e. high winds and temperature extremes of >30 or < 4 ºC). We hired a trained, certified tree-climber (Mark Bacro) who decided whether a given tree and nest could be safely accessed. A ropes method was used to climb the trees. This method was non-invasive and did not compromise the health of the tree. The ground crew was in constant contact with the climber via walkie-talkie. Mr. Bacro also provided us with details from the nest itself, including: prey remains in nest, nest dimensions, whether a waterbody was within the field of view, whether the nest was beneath the tree canopy cover, presence of likely perches within the field of view. Birds were removed from the nest by immediate capture by hand or by coaxing them toward the climber by using an “eagle stick.” They were then placed within a breathable bag, which was lowered via a rope system. No birds pre-maturely fledged or fell from the tree. MORPHOLOGICAL MEASUREMENTS Each nestling was measured and blood sampled in accordance with an approved animal care protocol (# 04-92), to obtain information on age, sex and condition (McCracken 2004). We collected a standard set of measurements for each nestling: body weight, culmen length, bill depth, food pad length, hallux claw length, and the length of the 8th primary feather. These measurements were subsequently used to age and sex the birds according to published formulae (Bortolotti 1984). All eaglets were checked for foot and bill abnormalities, and crop status was assessed (percent full). During the entire procedure, the bird’s physical status was continually monitored. If a bird appeared to be overheating, proper procedures were followed to cool the bird following the approved protocol. BANDING Once measurements were completed, the birds were banded. A hood was placed on the bird’s head. When not processing near the talons, the bird’s legs were wrapped using a sponge and Velcro. A standard size 9-rivet, USFWS aluminum band was placed on the right leg and a black and white alphanumeric, rivet band was placed on the left leg. To properly attach the band rivet, holes were aligned using a nail and needle-nosed vise grips were used to hold the alignment. The band was then secured with a pop rivet. This procedure was used for both bands and an overall inspection was made to ensure there were no rough edges and that they were attached properly. BLOOD SAMPLING Blood samples were collected from each nestling for contaminant analyses and sex determination. Once the bird was measured and banded, a 10 ml sample of blood was taken from the brachial vein under the proximal portion of the radius and ulna. A maximum of only two attempts to obtain the blood sample was permissible (one try per wing). If a sample could not be obtained after two attempts, the bird was considered a “non-donor.”


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The sampling area was cleaned using isopropyl alcohol, and downy feathers were pushed to the side to expose the skin and vein. We used a butterfly needle attached to a 10 ml vacutainer already containing freeze-dried Na Heparin. Immediately after sampling, the vacutainer was removed from the butterfly needle and rocked gently to ensure the contents were properly mixed. The sample was then placed on ice until it could be processed. Excess blood from the butterfly needle was blotted on specialized filter paper, which is used for sex determination, dried, and put in an envelope for shipping. Once samples were taken, the bird’s vein was monitored to ensure that the area was free from excessive bleeding or haematomas. In the event of a haematoma, pressure was applied to the vein to ensure it clotted properly and would not increase in size. Samples were put on ice until we were in an area in which we could properly process the samples. Samples were placed into a centrifuge, spun down for five minutes, and then the plasma was separated from the top of the red blood cells and placed into a nunc. This process was repeated until the plasma was completely separated. The nuncs were then placed into a portable dewar filled with liquid nitrogen. This kept the samples frozen until they could be returned to CWS for contaminants analyses. FEATHER SAMPLING Feathers were collected from each nestling for additional contaminant analysis. After banding, we took three breast feathers from the breastbone of each nestling. Feathers were sent to CWS for contaminant analysis. TRANSMITTER ATTACHMENT Three Platform Transmitting Terminals (PTT) were purchased in 2004, with funds generously donated by Ontario Power Generation (OPG). Three eaglets from two nest sites in Norfolk County received transmitters. In addition to the PTTs, VHF transmitters were also affixed, allowing us to track the birds intensively during the first two months following fledging – the period when mortality is expected to be greatest. Our PTTs were battery-powered and were factory outfitted with an auxiliary VHF transmitter allowing for this supplementary tracking. Each unit had a pre-set duty cycle, transmitting once every five days. The total weight of the assembly was approximately 93grams, which is less than three percent of the bird’s body weight. Eaglets for telemetry work were chosen based on their overall robustness, health and condition. The PTT back-pack was custom fit to the eaglet using Teflon ribbon as straps. The straps were sewn with biodegradable cotton thread. This method has been tested on numerous raptor species (including young eagles) and no negative impact has been reported on the flight, reproductive, or hunting abilities of the birds as a result of wearing transmitters. There have been no documented cases of eagles being injured as a consequence of carrying transmitters. Care was taken to ensure that the harness was loose enough to allow for growth of the bird, yet tight enough so as not to interfere with natural movements. Once the transmitter was fitted, the eaglet’s wing mobility was tested by doing a ‘flap test,’ while the bird is held by its legs. Once the harness was properly attached, the birds were returned to the nest. The birds were then monitored and observed from the ground to ensure there were no problems with attachment. If any problems


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had arisen, necessary efforts would have been made to recapture the bird and correct the problem. RETURNING NESTLINGS TO THE NEST After birds had been processed and all leg wrappings and hoods were removed, the birds were put back in the breathable lowering bag and raised back up the tree via rope to the climber. The climber then carefully returned the young to the nest, and quietly descended. The ground crew closely monitored the behaviour of the young during the complete duration of the climber’s descent, ensuring the birds remained in the nest. TRACKING AND DATA ANALYSIS Satellite transmission of the birds’ locations was timed to be received at BSC once every five days. Location data were put into a parsing program created by BSC’s senior scientists, Denis Lepage, which separates the satellite data into an Access database. This data are then imported into a real time mapping program, which is automatically updated each time a transmission is received. Movement data are reviewed and screened after each transmission is received. Once deemed to be sufficiently accurate, the data are then uploaded to an online tracking system (www.bsc-eoc.org) for the public to view on maps. Natal ranges, wintering ranges, and stopover sites will be determined by analyzing PTT data using Arcview GIS. More specific movement analyses will be carried out using the Animal Movement (Hooge and Eichenlaub 2000) extension available for Arcview. TERMINOLOGY For this report, territories were classified as occupied, empty, or abandoned. A territory was considered occupied if a pair of Bald Eagles was observed throughout most of the breeding season. A territory was classified as empty if a pair of eagles was present at least once in the last five years, but not present in 2004. A territory was classified as abandoned if there was no Bald Eagle activity during the past five years, or if the nest was destroyed. A nest was considered occupied if at least one of the following activities was observed during the breeding season: a) young were raised; b) eggs were laid; c) one adult sitting low in nest; d) two adults present on or near the nest, provided there was no reason to suspect they had been counted elsewhere; e) one adult and one sub-adult bird at or near a nest, engaging in mating behaviour; f) a recently built or repaired nest, and/or droppings or moulted feathers on the rim or underneath the nest; g) a single adult bird frequenting the territory for a substantial part of the breeding period (to at least early April). A nest was classified as active only if eggs were laid. Active nests differ from occupied nests in that non-nesting territorial pairs and sub-adults that occupy a breeding territory without actually


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laying eggs are excluded. Generally birds categorized as a), b), or c) above can be considered to have laid eggs (from Postupalsky 1974).

RESULTS UPDATE ON TERRITORIES THAT WERE NEW IN 2003 In 2003, we had recorded two new nesting territories in our study area -- PR1 and LG2. PR1 was the first confirmed Bald Eagle territory in the Peterborough area in many years. The pair added nesting material to a pre-existing Osprey nest, but failed to produce young, likely exhibiting ‘playing house’ behaviour (Buehler 2000). In 2004, a local cottager had noted this territory as being active, but no incubating behaviour or nestlings were noted. Therefore, the territory was occupied in 2004, but the pair did not reproduce. In 2003, an eagle pair occupied an Osprey nest at LG2 (Leeds-Grenville region) and brooding and incubating behaviour were noted in April. Two chicks were observed in June 2003. In 2004, the adults did not return and the territory was inactive. NEW TERRITORIES IN 2004 Seven new territories were established in 2004, of which five had activity at the nest, and two successfully produced young. A new territory (BR5) was located on an island off-shore from the Bruce Peninsula. An adult bird was seen perching at a nest tree in April. In May, two adults were seen over the island nest. However, there were no signs of eagles in early June, so the nest was considered inactive. This nest is on an island near a gull rookery, much like BR2. Essex County also had a new nesting pair that also chose an island in 2004. This was the first year a pair had been seen nesting on this part of the island. The EX6 pair successfully raised two chicks. HN6, a new nest in the Haldimand-Norfolk area, was not successful. Adult birds had been noted in the area through April 2004, but a storm in May likely caused the collapse of the nest. An inactive nest, but new territory, this year was KT3 in Kent County. The adults were seen in early spring, tending to the nest, but it is assumed they were only ‘playing house’ and moved on early in the summer. P Hunter (OMNR) suggests further investigation and follow-up into the fate of this nest in the coming years. In 2004, information was also received on two new nesting territories in the Peterborough region, PR2 and PR3. However, follow-up information for these two nests is lacking and more attention will focused on these nests in 2005 Long Point also had a new nest that will require closer attention next year, LP6. This nest was noted after fledging and it is suspected that the nest fledged at least a single young. Two BSC staff members observed an adult and juvenile at the new nest, however, total occupancy is unknown.


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Lastly, Middlesex County became home to a second pair of nesting Bald Eagles, at the MX2 site. The monitors for this nest provided very detailed information, and the nest was believed to have fledged one young.

NESTING ACTIVITY

In total, 47 Bald Eagle territories within the study area have been occupied at least once since monitoring began in 1980 (Appendix A). There are also non-occupied platforms (e.g. P11, PP1, and NA1), which despite reports of eagle activity in the area remain inactive. At other territories containing platforms (e.g., EN2, EN3, EX1), nesting activity has been observed in the past, but is currently inactive. Four historical nesting territories remained inactive this year (BR3, BR4, EN5, LG2). The nest at BR3 blew down in fall 2003, and there were no reports of the pair returning to the area in 2004. In 2003, LG2 was active and produced two chicks, but the nest later failed, apparently owing to predation. To aid in further nesting attempts a predator guard was subsequently placed on the nest tree. However, the pair did not re-nest in 2004, nor were any adults seen in the area. The pair at EN5 was successful in 2003, producing two chicks, but did not return to the nest in 2004. The pair at BR4 successfully raised two chicks in 2003, but did not return in 2004. NEST FAILURE AND ATTRITION There were five known nest failures in 2004, three due to natural destruction of the nest (e.g. wind), one likely a result of human disturbance, and one for unknown causes. At HN6, GY1, and EN2, territories were reported to be active, but all three nest sites were reported partially, or completely dilapidated and no chicks were produced. Pairs that did return to nesting territories and did not breed included: EX3, BR5, and HN5. At EX3, a pair was often seen circling the area and perching in the tree, but no nesting behaviour was seen, nor were any chicks produced. Nest BR5, already discussed within the new nest section, is a new nesting territory for 2004 and the pair did not display courting or breeding behaviour. Since human disturbance resulted in failure of the HN5 nest site in 2001, there has been no nesting activity. Adult eagles, however, continue to be seen within the territory, and three separate reports of eagles were received in 2004. Adults were observed perching on the nest tree early in the breeding season, a sub-adult bird was reported in the nest tree in early August, and an adult was seen standing on the nest in late September. It is likely that the same pair of eagles has occupied Turkey Point and Fisher’s Glen throughout the years, because the two territories are less than 10 km apart and have never been active in the same years. HN2 was active from 1990-1998, and HN5 was active from 1999-2001. After the HN5 nest was disturbed in 2001, the pair was observed the same season building a nest at Turkey Point. This nest was never used, but a new nest was constructed in Turkey Point marsh and was used from 2002-2004. Therefore, we speculate that following the disturbance at HN5, the pair subsequently relocated to HN2.


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BR2 was also abandoned, but not due to structural damage. Monitors noted a pair of adults adding sticks to the nest and preening one another in mid March. BSC staff observed the pair sitting tight to the nest in May. By June, however, the pair had abandoned the nest, and no chicks were noted. Activities near the nest site are speculated to have caused the abandonment. A large dock was constructed within about 400 metres of the nest. Close attention should be paid to this pair next year to ascertain whether the effects are long-lived. PRODUCTIVITY In 2004, there were 31 known active Bald Eagle nests within the study area, of which 25 successfully reared at least one young (Table 1, Table 3, Fig. 2). A record 46 young were produced overall, with a mean productivity of 1.48 fledglings per active nest (Table 3, Fig. 3). Success rate (81% vs 89%) and mean number of young produced were slightly lower than in 2003 (Debreceni and Badzinski 2003). In 2004, most nests produced two young (52%) and a record number of five eagle pairs produced triplets. This exceeds the 2003 record of four pairs producing triplets (Debreceni and Badzinski 2003). Pairs nesting at EN3 and HN2 successfully produced triplets for the first time since 1998 (HN2) and 1999 (EN3) respectively. The pair at LP3 had its first-ever record of triplets; its highest production in the past was two young in 1995. BANDING AND BLOOD SAMPLING The last intensive monitoring program (i.e., banding and blood sampling), took place in 1999, and is now done every five years. In 2004, 10 nests were accessed, and 21 eaglets were banded and blood sampled. Satellite PTTs were deployed on three of these birds (Table 4). An additional two eaglets were banded and blood sampled at LG1 through the cooperative efforts of members of the St. Lawrence Bald Eagle Working Group. In two cases, nest access was aborted, once due to high winds and the other due to an awkward and non-accessible nest. Young did not pre-fledge from any of the nests accessed, and we did not have any complications with regards to blood sampling (e.g., haematomas). A blood sample was obtained from all juveniles that were accessed. In only six circumstances was blood sampling attempted from both wings. SATELLITE TELEMETRY To date, satellite telemetry has proven to be a worthwhile effort towards learning more about the movements of southern Ontario Bald Eagles. In June 2004, three female eaglets were tagged with PTT units - two from HN2 and one from LP3. Ontario Power Generation, which funded the telemetry work, affectionately named the birds Olivia, Pamela (HN2), and Genna (LP3). Thus far, two of the three birds are still being tracked by satellite, Olivia and Pamela (Fig. 4). Both Olivia and Pamela fledged before 1 July. Olivia was the first of the two siblings to move more than 10 km from natal nest area. By 9 August, Olivia began to move in a northwesterly direction, reaching the Bruce Peninsula and Manitoulin Island by mid-August. She then moved


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as far as Sault St. Marie on 25 August and then returned to the Manitoulin Island area on 6 September. Olivia spent 40 days within the Manitoulin Island area until 16 October, when PTT transmissions revealed that she moved westerly through Sault Ste. Marie and into upstate Michigan. Pamela left the same natal nest area at HN2 on 1 September, traveling in a northwesterly direction to the eastern shores of Lake Michigan. Five days later she was located moving through Detroit and she has since traveled south to the upper Mississippi River in northern Illinois. Genna, the only bird PTT tagged on LP3, was retrieved dead on 13 September 2004. For further details, see below. Preliminary analysis of the movements of the tagged birds suggests that the birds favoured large bodies of water and river tributaries. The PTT transmissions also demonstrate that the birds are active during the day and stationary during all evening transmissions. As well, siblings have been recorded traveling independently of one another, Olivia traveling north and then west and Pamela west and then south, immediately after dispersing from the natal area. EAGLE DEATHS

In 2004, only one of three eaglets from the LP3 nest survived. One of these birds had been fitted with a PTT (Genna, Table 4), and all three were banded. Poor transmission readings suggested that something was not quite right, and a field crew using VHF radio telemetry went to the nest site to find the bird. The carcass and PTT were retrieved, along with the carcass of one its siblings, which was discovered immediately beneath the nest. The bird fitted with the transmitter is estimated to have died around 20 August 2004. The harness was not caught up on the bird and was sitting properly on its back. Prior to its estimated date of death, this bird had been flying within its natal area. The estimated date of death for the other eaglet was 3 August, coinciding with a major storm that passed through the area. Both birds had been seen flying within their natal territory on 18 July and likely fledged in the first week of July. Both carcasses were sent to Dr. Kate Welch of the Canadian Cooperative Wildlife Health Center, at the University of Guelph. On 10 November, Dr. Welch reported that the birds did not die from an obvious physical wound or altercation. Unfortunately, lack of useable tissue prevented Dr. Welch from performing further tests. On 10 November 2004, OMNR retrieved the carcass of an adult female Bald Eagle from a farm field near Thamesville, in Chatham-Kent County. This bird was originally banded (2ER = black alphanumeric and 629-07419), at LP2 in June 1992. Hence, it was 12 years old at the time of death. The carcass was forwarded to Dr. Welch for necropsy.


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TABLE 1 – Summary of Bald Eagle nesting activity and productivity at each occupied territory in Southern Ontario in 2004. See Appendix A for history of nesting activity at each territory and Table 2 for additional details on territories and sightings. Territories were classified as active (A), occupied (O), abandoned (AB), or empty (E). Nests were classified as active (A, eggs laid), occupied (O, territory occupied but no eggs laid), or inactive (I, territory inactive). Productivity was defined as the number of young raised to fledging; indicates not applicable because territory and/or nest were inactive.

Territory ID Territory Status

Nest Status Productivity Comments

BRUCE BR1 O A 2 BR2 O A 0 See Table 2 for details. BR3 O I BR4 O I Mate change in 2003.

BR5 O I No eagles seen after June 2004. New

territory 2004 (see text). ELGIN EN1 AB AB No activity since 1984. EN2 O A 0 EN3 O A 3 Nest is on a platform. EN4 O A 2 EN5 E I 0 Birds may have moved to another nest. EN6 O A 2 EN7 O A 2 ESSEX EX1 O A 1 EX2 O A 2 EX3 O A Unknown if young were produced. EX4 O A 1 EX5 O A 1 EX6 O A 2 PI1 E I Platform has never been occupied. PI2 O A 2 PP1 E I Platform has never been occupied.


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TABLE 1 cont.



FRONTENAC FR1 O A 2 FR2 O A 2 Nest active, at least one young produced. GREY

GY1 O I Nest blew down last year and the new nest site is unknown.

HALDIMAND-NORFOLK

HN2 O A 3 HN3 O A 2 HN4 O A 2 HN5 O I See table 2 for details. LP1 O A 1 LP2 E I LP3 O A 3 LP4 O A Unknown if young were produced. LP5 E I

LP6 O A 1+ Unknown if more than one were produced. New territory 2004 (see text).

KENT KT1 O A 1+ Unknown if more than one were produced. KT2 O A 3 KT3 O I New territory in 2004 (see text) RP1 AB AB No activity since 1996. RP2 O A Unknown if young were produced. LAMBTON LB1 O A 3 LEEDS-GRENVILLE LG1 O A 2 LG2 E I


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TABLE 1 cont.



MIDDLESEX MX1 O A 1 MX2 O A 1 New territory in 2004 (see text) NIAGARA NA1 See table 2 for details. NORTHUMBERLAND

NH1 O A 1 PETERBOROUGH PR1 O I

PR2 O A __ New territory, unknown if young produced (see text).

PR3 O New territory, poorly monitored in 2004


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TABLE 2 – Additional details for Ontario Bald Eagle sightings and territories in 2004. Identifier Observations BRUCE BR2 Nest was occupied and adults were seen on nest in early

spring 2004. Failure occurred between 14 May and 22 May 2004. Birds may have abandoned while the standing docks were added to the island.

HALDIMAND- NORFOLK

HN5 Nest abandoned in 2001 as a result of human disturbance on site. Adult and juvenile Bald Eagles were observed in the territory and perched on nest tree in 2002. In 2004, there were reports of an adult in the nest tree during March, and a juvenile in the tree in early August. The presence of an adult standing on nest in late September was confirmed.

NIAGARA

NA1 Some eagle activity was reported during the winters of 2001-2003, but nesting did not occur.

TABLE 3 - Summary of Bald Eagle nesting activity in Southern Ontario in 2004.

Reproductive Parameter Value Number of occupied territories 40 Number of active nests 31 Number of successful nests 26 (84%) Number of failed nests 5 (16%) Nests that fledged 1 young 9 Nests that fledged 2 young 12 Nests that fledged 3 young 5 Total number of young produced 46 Young/occupied territory 1.2 Young/successful nest 1.8 Productivity (young/active nest) 1.48


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0

5

10

15

20

25

30

35

40

45

50

80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04

Year

Number

ACTIVE TERRITORIESSUCCESSFUL NESTSTOTAL YOUNG

FIGURE 1 - The number of successful Bald Eagle nests and active territories in Southern Ontario (bars), and the total number of eaglets produced (dots) from 1980-2004. A nest was classified as successful if at least one young survived to fledging.

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

1.60

1.80

80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04

Year

Productivity

FIGURE 2 - Productivity (mean number of chicks fledged per active nest) of Bald Eagles in Southern Ontario between 1980 and 2004.


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TABLE 4- Banding efforts for southern Ontario Bald Eagle monitoring program 2004

Nest ID Date Tree species Weight(lb) Banded Blood

sample Comments

EN3 02/06/04 White Pine 7.6 X X 9.0 X X 7.6 X X

Nest contents: misc. fish bones, crow tarsus, feathers, red fox fur

HN4 03/06/04 Red Oak 6.6 X X 9.0 X X

Both adults circled nest while we were processing the juveniles.

HN2 05/06/04 Black Maple 10.1 X X 9.4 X X 9.7 X X

Nest contents: remains of large-mouth bass, some skin still on fishing line, transmitters were put on two of the birds.

HN3 07/06/04 White Pine 9.9 X X 8.0 X X

Nest contents: small mammal skull, merganser wing

EX4 09/06/04 Cottonwood 7.1 X X Nest contents: silver bass (about 25 cm long), mostly intact; numerous fish skulls

KT2 11/03/04 Sugar Maple 7.5 X X 9.0 X X 8.9 X X

LP1 14/06/04 White Pine 7.0 X X Nest contents: numerous turtle shells (painted, map)

LP3 15/06/04 White Pine 10.8 X X 7.8 X X

One transmitter was deployed on an eaglet from this nest.

10.0 X X MX1 16/06/04 Sycamore 7.9 X X

Nest is small, low in the tree. Tree stands alone in a cow pasture.

LG1 22/03/04 White Pine 7.5 X X 9.1 X X

Birds banded and blood sampled by Peter Nye.


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FIGURE 3 - Both Pamela (circles) and Olivia (squares) began moving from their natal nest sites by the first week of August. Pamela traveled southwest to reach the upper Mississippi River by 22 September, and stayed there until mid-December. Olivia left her natal area by the end of July to reach the Bruce Peninsula by the first week of August, and she then traveled northwest to reach the Sault St. Marie area by the first week of November.

DISCUSSION

Within the last decade, the Bald Eagle population of Southern Ontario has steadily increased. Productivity has also increased, with the largest increase occurring between 2001 and 2002 (an increase of 1.5 to 1.6 young per active nest; 35 young to 44 young). Compared to 2003, nest productivity and number of young showed little change in 2004. A record number of nests fledged triplets in 2004, with a total of five pairs compared to four in 2003. The Bald Eagle population has increased considerably since the 1980s, due in part to the release of 32 young eaglets from hacking sites at Long Point and Taquanyah between 1983 and 1987, a decline in toxic chemicals over the last 30 years (Donaldson et al. 1999), and improved stewardship efforts.


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With the exception of those nests reporting triplets and those nests that were directly accessed by the field crew, productivity estimates are likely underestimated. The majority of nests are observed from the ground, which can be difficult at times due to poor visibility. Observers may, therefore, underestimate the number of chicks in a nest, particularly at nests that are visited on only a few occasions (Badzinski 2002). There are also a number of nests located in remote or inaccessible locations, which makes monitoring even more difficult. The possibility also exists that active Bald Eagle territories have not been reported to the Southern Ontario Bald Eagle Monitoring Project. Through increased public awareness of the program, and assistance of the second Ontario Breeding Bird Atlas, we can ensure new nests are reported and monitors located with efficiency. Some territories showed signs of attrition at established nesting sites in 2004. These natural occurrences are not uncommon, because nest trees are often old and at various stages of decay. Eagle nest trees have a limited life expectancy once a nest has established – only about 9.5 years according to Merkens et al. (1999). The use of artificial nest platforms can help increase the longevity of a nesting site if used consistently by an eagle pair. Currently, there are a number of unoccupied and inactive nest platforms in good condition and in areas known to be frequented by Bald Eagles. These sites should be closely monitored for future signs of nesting activity. Efforts have been made by Essex County residents to improve existing nesting habitat of a pair of eagles nesting along the Detroit River, with community members raising money and supplies to erect a nesting platform in a pre-existing tree adjacent to the dilapidated nest which will likely blow down within the next two years. Establishing a nesting platform within an existing active breeding territory may facilitate nesting in the future, if the original nest tree is no longer available (Postupalsky 1978). In order to maintain a stable Bald Eagle population, it has been estimated that a minimum of 0.7 young per occupied nest site is required (Merkens et al. 1999). While the current Southern Ontario population exceeds this threshold, survival rates of Bald Eagles likely have a greater effect on population dynamics than reproductive rates (Harmata et al. 1999). Although a significant population recovery has occurred since the 1980s, the long-term viability of Bald Eagles in the lower Great Lakes regions is still of concern. Turnover rates in adults within nesting territories, generally associated with adult mortality (P. Hunter pers. comm.), were estimated to be quite high (once every 11 years), given their normal life expectancy of 20 to 25 years (Buehler 2000). In addition, there have been several instances of adult mortality reported to the Southern Ontario Bald Eagle Monitoring Project over the last three years. Further research into reasons behind high turnover rates, and possibly high mortality rates, is warranted. Although levels of organochlorine compounds, such as DDT and PCBs, have been significantly reduced within the Great Lakes, Bald Eagles remain threatened by other sources of contamination. Recent years have shown the appearance of Type E botulism in the lower Great Lakes, which has killed large numbers of fish-eating waterbirds. The extent to which eagles may consume the carcasses of botulism-killed fish or birds is unknown, but this is a potential threat (Badzinski 2002). Perhaps more of a threat is the presence of heavy metals, in particular lead and mercury (Neilson and Pollock 2001). In the last several years, elevated levels of these substances have been noted in several Bald Eagles that were found dead in Ontario (P. Hunter,


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D. Campbell and M. Taylor, unpubl. data). Determining the extent to which heavy metal exposure may pose a long-term problem and may be responsible for decreased longevity has been identified by the project management team as a research priority. Results of contaminant analysis of 2004 sampled birds will be supplied by CWS once completed. In 2004 three juvenile eaglets from the Long Point region were tagged with satellite telemetry units and an interactive online tracking system was developed. To date, the birds are displaying nomadic behaviour characteristic of young juvenile eagles (Mabie et al. 1994; Wood et al. 1998; Restani et al. 2000; Laing et al. 2002), which do not need to obtain and occupy a breeding territory (Ueta et al. 2000). Not surprisingly, the movements of the PTT-tagged birds tend to follow riverways, lakes, and tributaries, likely reflecting a direct relationship to preferred food resources (Wood et al. 1998, Restani et al. 2000, Laing et al. 2002). Both PTT-tagged birds only moved during diurnal periods. Such findings are similar to reports summarized by Buehler (2000), which suggest that Bald Eagles move during the day and perch during the evening. The online tracking program, “Eagle Tracker,” has provided this project with additional monitoring support from the general public. It is through this online tracker program that the two PTT tagged birds can be monitored and tracked. This feature permits the interested public to learn about and participate in eagle monitoring efforts in southern Ontario.

CONCLUSIONS In 2004 the fate of 31 active nesting territories were recorded, yielding reports on 25 successful nests, which produced a cumulative of 46 young. A total of 10 nests were accessed, and 21 young were banded and blood sampled. Satellite telemetry efforts have provided immediate results, reporting the early fledging movements of the tagged juveniles by 1 July 04, and the far ranging dispersal patterns of these young birds less than a month after fledging. Satellite telemetry has already alerted us to the reality of this species low survival rates within their first year, allowing us to track Genna to her early death (estimated 20 Aug 04) only to find her sibling had also died.

RECOMMENDATIONS The following recommendations should frame a work plan for the Southern Ontario Bald Eagle Monitoring Project in 2005:

• Continue to monitor all territories and nests within the study area and closely monitor

territories that had failed nests in 2004. • Closely monitor those territories that were new in 2004 for signs of nesting activity. • Continue to monitor abandoned territories for the possibility of reoccupation. • Closely monitor inactive platform sites. • Increase public awareness of the Southern Ontario Bald Eagle Monitoring Project and

continue to work with the Ontario Breeding Bird Atlas so that all nests have monitors designated in a timely fashion.

• Work with landowners to increase awareness and to protect Bald Eagle nesting habitat. • Focus on determining sources of mortality in adult and juvenile eagles.


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• Continue to investigate dispersal patterns of free-flying juveniles and young adults through satellite tracking technology.

• Sample blood and feathers from eaglets at five nests in 2005.

ACKNOWLEDGMENTS The Southern Ontario Bald Eagle Monitoring Program could not be conducted without the help of many dedicated individuals. A big thank-you goes out to the landowners and nest monitors who have grown too numerous to mention personally. Each have shown strong commitment and dedication to Bald Eagles in Ontario, and continue to make the monitoring program a success. Special thanks to Doug Baird, Marshall Field, Phil Roberts, John Rouselle, Danny Bernard and Paul Ashley (CWS), Bob Flourean (OMNR), Susan Debreceni (BSC) and N.E.S.T., for their dedicated support of this project. Thanks also to Dr. Kate Welch (Canadian Cooperative Wildlife Health Centre) for necropsies of deceased Bald Eagles, and to Dr. M. Taylor (Avian and Exotic Service) for assessment and rehabilitation. Laird Shutt (CWS) who provided equipment, advice and training and Mark Bacro (BSC) who braved the elements and climbed all those trees made gracious contributions of their time and resources. Andrew Couturier and Denis Lepage (BSC) provided a great deal of technical assistance in the development of the “Eagle Tracker” program. Thanks to Jon McCracken and Debbie Badzinski (BSC) for project management and for reviewing earlier versions of this report. An extended thank you to Jamie Cowan (Canadian Raptor Conservancy), who provided generous advice and support throughout the field season. This project was made possible with funding from the Canadian Wildlife Service, Ontario Ministry of Natural Resources, Ontario Power Generation, the Edwards Charitable Foundation, and private donors, with the cooperation and in-kind contributions of Bird Studies Canada, Canadian Wildlife Service, Ontario Ministry of Natural Resources, volunteers and landowners. Southern Ontario Bald Eagle Monitoring Program - Management Team (2004) Dawn Laing, Bird Studies Canada Debbie Badzinski, Bird Studies Canada Pud Hunter, Ontario Ministry of Natural Resources Pamela Martin, Canadian Wildlife Service Jon McCracken, Bird Studies Canada Chris Risley, Ontario Ministry of Natural Resources Dr. Laird Shutt, Canadian Wildlife Service Donna Stewart, Canadian Wildlife Service


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LITERATURE CITED Austen, M. J. W., M. D. Cadman, and R. D. James. 1994. Ontario Birds at Risk: status and

conservation needs. Federation of Ontario Naturalists and Long Point Bird Observatory, Ontario. 165 pp.

Badzinski, D.S. 2002. Southern Ontario Bald Eagle Monitoring Project, 2002 report.

Unpublished report by Bird Studies Canada to the Ontario Ministry of Natural Resources and the Canadian Wildlife Service. 16 pages.

Buehler, D.A. 2000. Bald Eagle (Haliaeetus leucocephalus). In Birds of North America, No. 506

(A. Poole and F. Gills, eds.). The Birds of North America, Inc., Philadelphia, PA. Bortolotti, G.R. 1984. Criteria for determining age and sex of nesting Bald Eagles. J. Field

Ornithol. 55(4): 467-481. Debreceni, S.M. and D.S. Badzinski. 2003. Southern Ontario Bald Eagle Monitoring Project,

2003 report. Unpublished report by Bird Studies Canada to the Ontario Ministry of Natural Resources and the Canadian Wildlife Service. 20 pages.

Donaldson, G. M., J. L. Shutt and P. Hunter. 1999. Organochlorine contamination in bald eagle

eggs and nestlings from the Canadian Great Lakes. Arch. Environ. Contam. Toxicol. 36: 70-80.

Harmata, A. R., G. J. Montopoli, B. Oakleaf, P. J. Harmata, and M. Restani. 1999. Movements

and survival of Bald Eagles banded in the Greater Yellowstone ecosystem. J. Wild. Manage. 63: 781-793.

Laing, D.K., D. Bird, T. Chubbs, and G. Humphries. 2002. Migration routes, timing, and nest

site fidelity of Osprey (Pandion Haliaeetus) and bald eagles (Haliaeetus leucocephalus) as they relate to military aircraft activity in Labrador. IN BirdStrike 2002 Conference Preceedings, August 19-21 2002, Toronto, Ontario.

Mabie, D.W., M.T. Merending, and D.H. Reid. 1994. Dispersal of bald eagles fledged in Texas.

J. Raptor Res. 28(4): 213-219. McCracken, J.D. 2004. A protocol for monitoring productivity, contaminant-loadings and

movements of Bald Eagles in the Great Lakes Basin. Unpubl. rept. from Bird Studies Canada to Ontario Ministry of Natural Resources Animal Care Committee. 12 pp. + appendices.

Merkens, M., B. Booth, and M. D Wood. 1999. Osprey and Bald Eagle productivity and habitat

use in the Willingston Reservoir watershed, North-Central BC, 1997. Peace/Williston Fish and Wildlife Compensation Program, Report No. 202. 52 pages.

Neilson, A. L.,. and J. S. Pollock. 2001. Bald Eagle populations in the Great Lakes region: back


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from the brink. Environment Canada, Great Lakes Fact Sheet 93-3:1-12. Postupalsky, S. 1974. Raptor reproductive success: some problems and methods, criteria, and

terminology. pp. 21-30 In: F. N. Hamerstrom Jr., B. E. Harrell, and R. R. Olendorff (eds.). Management of Raptors, Proceedings of the Conference on Raptor Conservation Techniques, Fort Collins, Colorado, 22-24 March 1973.

Postupalsky, S. 1978. Artificial nesting platforms for ospreys and bald eagles. Pp. 34-45 In:

S.A. Temple ed., Endangered birds-management techniques for preserving threatened species. University of Wisconsin Press, Madison, WI.

Restani, M., A. Harmata, and E. Madden. 2000. Numerical and functional responses of migrant

bald eagles exploiting a seasonally concentrated food source. Condor 102:561-568. Ueta, M., F. Sato, H. Nakagawa, and N. Mita. 2000. Migration routes and difference of

migration schedule between adult and young Steller’s Sea Eagles Haliaeetus pelagicus. Ibis 142:35-39.

Weekes, F. 1974. A survey of bald eagle nesting attempts in southern Ontario, 1969-1973.

Canadian Field Nat. 88:415-41. Wood, P.B., M.W. Collopy, and C.M. Sekerak. 1998. Postfledging nest dependence period for

bald eagles in Florida. J. Wildl. Manage. 62(1):333-339.

APPENDIX A – Productivity of Southern Ontario Bald Eagle nests, 1980-2004 (mean = total/#years nest occupied). AB=abandoned, P=unoccupied platform, U = unknown.

ID 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 Total MeanBR1 2 1 2 5 1.5BR2 BR3 BR4 1 1 2 1.0EN1AB 0 0 1 1 0.3EN2 0 0 0 0 1 1 0 0 1 0 0 0 1 1 1 0 2 2 2 1 1 14 0.7EN3 0 0 1 1 2 2 3 1 0 3 1 3 3 3 3 2 2 2 0 3 35 1.7EN4 0 0 1 0 1 1 3 2 2 10 1.0EN5 1 2 2 1 3 0 2 11 1.6EN6 0 0 1 0 2 3 0.3EN7 2 3 3 2 10 2.7EX1 0 0 0 0 2 2 1 0 0 0 1 2 3 1 1 0 2 2 1 2 0 2 2 2 1 27 1.1EX2 1 2 2 1 2 2 3 2 1 2 1 2 1 1 2 3 0 2 0 2 2 2 2 38 1.6EX3 0 2 1 2 1 1 1 3 3 2 2 2 2 2 2 U 26 1.7EX4 0 0 1 1 2 3 1 1 2 2 2 2 1 18 1.4EX5 U 2 1 3 2.0EX6 2 2 PI1P PI2 1 1 3 2 2 1 2 12 1.7PP1P FR1 2 2 3 3 2 12 2.5FR2 1 1 1 2 5 1.0GY1 1 2 1 2 2 0 0 0 1 U 1 10 1.0HN1AB 0 0 0 0 0 0 0.0HN2 0 0 2 2 2 2 1 0 3 2 2 3 19 1.5HN3 1 2 2 2 2 3 2 2 2 0 18 1.8HN4 0 1 1 2 2 2 2 2 2 2 2 18 1.6HN5 2 1 0 3 1.0LB1 2 3 3 8 2.5LP1 2 0 1 0 1 0 2 2 1 0 1 1 0 1 0 0 1 2 1 1 1 1 19 0.9LP2 2 0 2 1 2 2 1 0 0 0 2 2 1 1 1 3 20 1.3LP3 1 2 0 1 0 1 1 1 1 3 11 0.9LP4 0 1 U 1 0.5LP5 1 1 1.0LP6 1 1 1KT1 0 1 1 3 1 1 1 1 1 2 1 13 1.2KT2 2 2 3 7 2.0KT3 1.0RP1AB 0 0 1 2 3 2 1 1 2 2 1 0 0 0 1 0 16 1.0RP2 2 1 1 0 1 1 2 2 2 U 12 1.3

LG1 1 0 1 2 1 2 7 1.0APPENDIX A cont.

ID 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 Total MeanLG2 0 0.0MX1 1 1 1MX2 1 1 1NA1P NH1 2 0 0 0 1 1 1 5 0.7PR1 PR2 U PR3 Total 0 1 5 5 7 6 5 6 10 7 11 11 15 13 13 18 23 21 26 24 29 35 44 44 46 379 1.3

Southern Ontario Bald Eagle Monitoring Project · Eagle deaths ... food pad length, hallux claw...

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