Post on 05-Jan-2019
Seasonal Sights and Sounds of
Alberta: Osprey
Dr Sally Stuart
The Ospreys appeared for the first time in the summer of 2013. They
were almost certainly two-year olds. They were too young to breed but
they still built a huge precarious nest on the top of a transformer pole. In
2014, they returned. They descended on the trees, exhibiting incredible
strength as they broke off huge branches to construct their nest. They
then settled down to breed. That year they successfully raised three
young, followed by two in each subsequent year.
Ospreys are fascinating birds. There is a differences in the sexes (sexual
dimorphism) which is seen not in their appearance but in their behav-
iour. Among most bird species, the male and female have somewhat
different roles in the breeding season; the Osprey has taken these role
differences to the extreme. The male will do nearly all the fishing for a
four to five month period (imagine the quantity of fish needed to feed
both adults and to raise two young that will each attain a mature weight
of 1.5 kg. The female rarely leaves the nest, concentrating on egg laying
and incubation, and defending the nest and young, During this time, she
is entirely dependant on the male for food.
The remarkable breeding success enjoyed by our neighbourhood pair is
likely because there are no other Ospreys or Bald Eagles nearby. To find
fish, the male has to fly about five km to Sylvan Lake or even further to
the Blindman River.
Ospreys are well adapted for fishing. Unlike other perching birds(which
have three toes at the front and one at the back), Ospreys have zygodac-
tyl feet : two forward-facing and two rear-facing toes. This arrangement,
combined with massive curved talons and roughened scales on the soles
of their feet (spicules), allows them to grasp fish. The practice of fishing
is not without risks; birds may drown if they lock onto a heavy fish and
cannot get airborne Diving into the water to get fish requires extensive
water proofing of the feathers, so birds will preen themselves and smear
oil on their feathers from the uropygial gland located just above the base
of the tail.
While their anatomical specializations for fishing are remarkable, so is
the Osprey’s visual acuity. The ability for raptors to see fine detail is evi-
dent in research by Fox et al., who reported the American Kestrel can
see a 2- mm insect from the top of an 18-m high tree, quite incredible!
Osprey eyes are relatively large are of the optimum size-weight ratio.
The physiology and anatomy of eyes are fascinating. In order to see, light
must be focused by the lens on the retina, a thin membrane at the back
of the eye. Hawks and eagles have remarkable retinas (where the special-
ised rod and cones cells are found). Cones respond to bright light and are
responsible for colour vision. Raptor eyes have approximately five times
more cones per square
millimetre than human
eyes.
Eye retinas contain a de-
pressed area (fovea) which
have the highest concen-
tration of cones. Humans
have one central fovea,
which is important for image sharpness. Raptors have two fovea: the
deep and the shallow. The deep fovea provides excellent distant vision
with very high resolution (the ability to discriminate two separate points).
It is apparently directed at about 45 degrees to the side of the head, an
arrangement which provides the bird with binocular vision. The shallow
fovea is responsible for monocular and close-up vision.
All the cells in the retina require a vast supply of nutrients but— unlike
humans—birds do not have blood vessels in the retina because blood
may interfere with vision. Instead, they have a specialised structure called
the pectin. The pectin is attached to the retina near the optic nerve and
interferes less with visual function. In raptors, the pecten is large and
complex.
Another eye adaptation is the presence of a third eyelid, called the nicti-
tating membrane. This thin and transparent membrane is engaged when
the bird dives, acting much like swimming goggles.
Osprey behavioural sexual dimorphism has resulted in unique acoustic
and visual signals. These signals are important, especially for the female
who spends so many months defending and protecting young at the nest.
The sonogram, below, shows the typical alarm call which most people
are familiar with. The call, which consists of a series of short (about
0.05s) low frequency sounds with a series of harmonics, will carry a long
distance.
Osprey also have screaming and guard calls for protection, excitation and
copulation calls. These calls are made by both birds; however, as the
female is particularly dependant on the male for food she also has three
calls entirely devoted to solicitation for food!
In September the Ospreys leave Central Alberta and begin their migra-
tion south, often returning to the same wintering grounds each year.
Studies show that breeding pairs do not tend to migrate or overwinter
together, and that the female will often depart while the male continues
fishing for the offspring. Juvenile Osprey migration is remarkable: young
that have flown only short distances for short periods of time depart on
a first-time journey that will take them across the ocean for up to 35-54
hours of non stop-flight, often covering distances of over 2,000kms
October fades into November; still the nest continues to provide inter-
est. Occasionally, it is occupied by Canada Geese, even a comical group
of migrating Double-crested Cormorants pause there for a brief hour or
two. So we wait for spring and the day when the Ospreys will return.
MAY 27, 28 Species Count Summary
Snow Goose 2
Cackling Goose 2
Canada Goose 1332
Trumpeter Swan 1
Gadwall 155
American Wigeon 20
Mallard 709
Blue-winged Teal 387
Cinnamon Teal 19
Northern Shoveler 217
Northern Pintail 18
Green-winged Teal 60
Canvasback 39
Redhead 120
Ring-necked Duck 133
Lesser Scaup 239
Bufflehead 153
Common Goldeneye 61
Hooded Merganser 1
Common Merganser 15
Ruddy Duck 134
Gray Partridge 7
Ring-necked Pheasant 1
Ruffed Grouse 4
Common Loon 5
Pied-billed Grebe 2
Horned Grebe 7
Red-necked Grebe 33
Eared Grebe 87
Western Grebe 2
American White Pelican 22
Double-crested Cormorant 33
American Bittern 2
Great Blue Heron 15
Turkey Vulture 9
Osprey 7
Bald Eagle 8
Northern Harrier 7
Cooper's Hawk 1
Broad-winged Hawk 1
Swainson's Hawk 11
Red-tailed Hawk 78
Rough-legged Hawk 1
Sora 19
American Coot 185
Sandhill Crane 6
Killdeer 23
American Avocet 26
Spotted Sandpiper 16
Solitary Sandpiper 2
Greater Yellowlegs 2
Willet 11
Marbled Godwit 2
Wilson's Snipe 24
Wilson's Phalarope 51
Bonaparte's Gull 9
Franklin's Gull 1
Ring-billed Gull 154
California Gull 1
Black Tern 44
Common Tern 11
Forster's Tern 13
Rock Pigeon 86
Eurasian Collared-Dove 15
Mourning Dove 13
Great Horned Owl 14
Great Gray Owl 1
Long-eared Owl 5CW
Short-eared Owl 1
Northern Saw-whet Owl 5
Ruby-throated Hummingbird 4
Belted Kingfisher 2
Yellow-bellied Sapsucker 6
Downy Woodpecker 8
Hairy Woodpecker 4
Northern Flicker 8
Pileated Woodpecker 5
American Kestrel 8
Merlin 4
Prairie Falcon 1
Western Wood-Pewee 6
Alder Flycatcher 1
Least Flycatcher 42
Eastern Phoebe 7
Western Kingbird 2
Eastern Kingbird 1
Warbling Vireo 8
Red-eyed Vireo 5
Gray Jay 3
Blue Jay 13
Black-billed Magpie 151
American Crow 224
Common Raven 77
Purple Martin 59
Tree Swallow 374
Northern Rough-winged Swallow 15
Bank Swallow 372
Cliff Swallow 844
Barn Swallow 55
Swallow species 15
Black-capped Chickadee 58
Boreal Chickadee 4
Red-breasted Nuthatch 18
White-breasted Nuthatch 12
House Wren 84
Marsh Wren 20
Ruby-crowned Kinglet 5
Mountain Bluebird 71
American Robin 189
Gray Catbird 9
European Starling 517
Cedar Waxwing 3
Common Yellowthroat 6
Yellow Warbler 184
Yellow-rumped Warbler 21
Spotted Towhee 1
American Tree Sparrow 2
Chipping Sparrow 38
Clay-coloured Sparrow 154
Vesper Sparrow 36
Lark Sparrow 1
Savannah Sparrow 90
Song Sparrow 52
Lincoln's Sparrow 2
White-throated Sparrow 23
White-crowned Sparrow 14
Dark-eyed Junco 5
Rose-breasted Grosbeak 8
Red-winged Blackbird 778
Western Meadowlark 56
Yellow-headed Blackbird 123
Brewer's Blackbird 290
Common Grackle 14
Brown-headed Cowbird 50
Baltimore Oriole 29
Purple Finch 8
House Finch 27
Pine Siskin 8
American Goldfinch 44
Evening Grosbeak 2
House Sparrow 100
COMPILER: JUDY BOYD
Participants: 39 – Jana Biber, Karin Bjorge, Myron Bjorge, Helene Boulan-
ger, Jim Boyce, Judy Boyd, Larry Boyd, Alexandra Braun, Colleen Caddy,
Jerry Caddy, John Caddy, Anto Davis, Bev Ewanchuk, Bertha Ford, Eileen
Ford, Jordan Ford, Laurel Ford, Stewart Ford, Jane Grenier-Frank, Laura
Fritz, Ben Giese, Bill Heinsen, Scott Hoyland, Carol Kelly, Keith Kline, Joyce
Lemke, Shelley Macauley, Laura Oomen, Myrna Pearman, Doug Pedersen,
Bonnie Potter, Jim Potter, Brooke Rafferty, Marg Ramsay, Brooklyn Rose,
Kim Siebold, Joanne Susat, Rick Tallas, Rick Varjassy
Area Covered: Zone 1 (Red Deer), Zone 2 (Sylvan Lake), Zone 3 (Gull Lake),
Zone 4 (Lacombe), Zone 6 (Pine Lake), Zone 7 (Penhold), Zone 8 (Dickson,
MRWC), Zone 11 (Rimbey/Bluffton), Zone 12 (Crestomere), Zone 16
(Lousana), Zone 17 (Bigelow Reservoir), Zone 25 (Three Hills), Zone 26 (Dry
Island Buffalo Jump), and Zone 27 (Rocky Mountain House).
Weather: Day 1: Temp. 8 to 25 C; Wind speed: 0 to 40 km/hr. Wind direc-
tion: variable; Cloud cover: 0-50%
Day 2: Temp. 14 to 24 C; Wind speed: 0 to 35 km/hr. Wind direction: varia-
ble; Cloud cover: 0-50%
Team Distance/Hours: Total Team Mileage: 1318.9 km; by vehicle 1256.7
km; on foot 56.2 km; by bicycle 6 km. Total Team Hours: 121 hr; by vehicle
67 hr.; on foot 27.5 hr, by bicycle 2 hr, by canoe 1 hr; feederwatch 23.5 hr.
Number of Species: 143 + 1 CW; Number of Birds: 10381 + 5 CW
Highlights: Highest recorded numbers since 2000: 2 Belted Kingfisher (tied
with 2008), 15 Eurasian Collared-Dove, 372 Bank Swallows. This was the
first time since 2000 that a Cackling Goose and Great Crested Flycatchers
were counted. This was only the second time Broad-winged Hawk and
Snow Goose were counted (both times were last counted in 2013).
Count Week birds were 5 Long-eared Owls seen on May 31.
Number of participants was down from last year's 47 to 39. The number of
bird species went up from last year's 140 to 143. (The highest recorded
number of species since 2000 was in 2008: 153.) The count of individual
birds was down from last year's 1,3126 to 1,0381.
Thanks to Judy Boyd for organizing RDRN bird counts!
Front cover designed by Doug Pederson
In Memoriam: Long-time RDRN mem-ber, Dorothy Hazlett, passed away on Au-gust 15. A celebration of her life will take place on Saturday October 14 at 2:00 PM at Gaetz Memorial United Church Hall, 4758 Ross St., Red Deer. A tribute to Dor-othy will be included in the November newsletter.
The Red Deer River Naturalists, the first natural history organization to be
established in Alberta, was incorporated as a society in 1906. The objec-
tives of the society are to foster an increased knowledge, understanding
and appreciation of natural history, and to support conservation measures
dealing with our environment, wildlife and natural resources.
Annual membership is $15.00 for individuals and $30.00 for families.
Membership period: January 1—December 31.
Regular meetings are held at 7:30 p.m. on the fourth Thursday of most
months at the Kerry Wood Nature Centre, 6300-45 Ave., Red Deer, AB.
Non-members are welcome.
Members are encouraged to contribute to this newsletter. Deadline is the
last Friday of the month.
Box 785 Red Deer, AB T4N 5H2
Phone/Fax: 403.347.8200
rdrn.nature@gmail.com www.rdrn.ca
http://wearenaturalwise.blogspot.com
May Species: Other Animals
Mammals: Beaver, Coyote, Elk, Mule Deer, Muskrat, Red Fox, Red Squirrel, Richardson's Ground Squirrel, Thirteen-lined Ground Squirrel, White-tailed Deer,
Amphibians: Boreal Chorus Frog, and Wood Frog
Insects: Alfalfa Butterfly, Boreal Bluet, 2 queen bum-blebees, bumblebee, Cabbage Butterfly, Canadian Tiger Swallowtail, Cherry-faced Meadowhawk, drag-onflies, damselfilies, Field Cricket, fritillary, Green Comma, Hudsonian Whiteface, Red-winged Click-hoppers, Whirligig Beetle, Wood Ant
Birding hikes
Photos by Myrna Pearman unless otherwise noted
NOTE: In September, hikes will start at 10:00 AM. From October 7 to December 9, hikes will start at 1:30 PM.
September 2— Heritage Ranch. Meet in the first parking lot.
September 9—Hazlett Lake. # 27432 West on Hwy 11 A . Take the last entrance before Hwy 2. I’ll be standing at the entrance.
September 16 - Slack Slough and Cooty Pond
September 23—O’Brien Wetland
September 30—Nova Nature Walk. Google for di-rections.
October 7—Maskapatoon
October 14—Three Mile Bend Meet in the first park-ing lot on your right.
October 21—River Bend Golf Course. Meet in the parking lot on your right at the bottom of the en-trance to River Bend
October 29—Heritage Ranch
November 4—Mackenzie Trails
November 18—Bower Woods. Meet on Selkirk Drive in front of #35.
November 25—Kin Kanyon. Meet at the Rotary pic-nic parking lot.
December 2—Gaetz Lakes Sanctuary. Meet at KWNC
December 9—Gaetz Lake.Meet at KWNC