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Aplomado Falcon (Falco femoralis septentrionalis)

Monitoring in Valles Centrales, Chihuahua, Mexico

Final Report

IMC VIDA SILVESTRE A. C. Chihuahua, Chihuahua

November 1, 2017

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Project Team:

Bird Conservancy of the Rockies (BCR)

Arvind Panjabi

Greg Levandosky

IMC Vida Silvestre A. C.

Nancy Hernández R.

Pedro Calderón D.

Roberto Rodríguez S.

Universidad Estatal de Sonora

Alberto Macías D.

Voluntarios

Manuel Ochoa B.

Gabriela Mendoza G.

Gerardo Valenzuela B.

Special thanks to:

BCR for launching this project. Alberto Macías for sharing his advice and experience, as well as

for obtaining permission to monitor. Ángel Montoya kindly donated the bands to place on the

chicks. Finally, to the owners and cowboys of the ranches in which the Aplomado Falcon

monitoring project was conducted for their commitment to the protection and sustainable use of

grasslands:

Nicolás Yapor and family

Alfredo Prieto

Baeza families

Family Borunda Carrillo

Family Cinco Baeza

Cover Photo: Falco femoralis banded fledgling, Roberto Rodríguez

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Table of Contents:

Project team………………………………………………………………………………………2

Acknowledgments………………………………………………………………...……………...2

Table of Contents…………………………………………………………………………………3

Executive Summary………………………………………………………………………………4

Introduction……………………………………………………………………………………….4

Materials and Methods……………………………………………………………………………6

Status of Aplomado Falcon territories…………………………………………………………8

Results…………………………………………………………………………………………….8

Nesting structures utilized…………………………………………………………………….12

Reproductive productivity…………………………………………………………………….12

Conclusions and recommendations……………………………………………………………...18

Literature Cited…………………………………………………………………………………..19

Appendix: Research permit issued by Dirección General de Vida Silvestre……………………20

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Executive Summary

As part of the wildlife conservation and habitat management efforts of The Bird

Conservancy of the Rockies and IMC Vida Silvestre with the support of the State University of

Sonora, Aplomado Falcon (Falco femoralis septentrionalis) monitoring was carried out in the

Chihuahuan Desert via monthly visits to historic nesting territories, as well as monitoring by

satellite telemetry of some fledglings. 24 historic territories of Aplomado Falcon were

monitored, in which eight pairs were detected, of which seven nested. Of these, two nests were

depredated and five successful, which produced 15 successful fledglings. Successful nesting

structures included a high voltage transmission tower, two artificial nest platforms, two Yucca

elata (soaptree yucca) plants, while unsuccessful nests were in Prosopis glandulosa (honey

mesquite) and Yucca elata. The population of Aplomado Falcons was found to be at least 31

individuals.

Introduction

The Aplomado Falcon (Falco femoralis) is a threatened species in Mexico according to

Mexican Law NOM-059-SEMARNAT-2010 (SEMARNAT 2010), with Falco femoralis

septentrionalis being the subspecies found in our country (Keddy-Hector 2000). The Aplomado

Falcon has a disjunct historical distribution in Mexico comprising two main distribution areas: 1)

northern Mexico, which includes the Chihuahuan Desert grasslands in the states of Sonora,

Chihuahua, Durango and Coahuila, and 2) eastern Mexico, including the tropical savannas of the

Gulf of Mexico in the states of Tamaulipas (Rodríguez-Ruíz et al., 2012), Veracruz, Tabasco,

Chiapas, Campeche and Yucatán (Keddy-Hector 2000). The northern limit of the historic

distribution of the Aplomado Falcon of the desert includes west Texas, southern New Mexico

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and southeastern Arizona. The Aplomado Falcon was common in the pastures of the Chihuahuan

Desert of the USA until about 1930 (Keddy-Hector 2000) when its decline began, with the last

recorded nesting near Deming, New Mexico, in 1952 (Ligon 1961).

In 1992, a previously unknown population of Aplomado Falcons was discovered in the

desert grasslands of the north-central state of Chihuahua, in the municipalities of Ahumada,

Chihuahua and Coyame (Montoya et al., 1997, Montoya 1995). Since then, there has been

research on the reproductive biology, habitat and prey of this Aplomado Falcon population

(Macías-Duarte 2002, Montoya et al 1997, Macías-Duarte et al 2009, Macías-Duarte et al 2004,

Mendez -Gonzalez 2000; Macias-Duarte et al., 2016), as well as the effect of pesticides (Mora et

al., 2011; Mora et al., 2008). This population in Chihuahua is of interest for the conservation of

the Aplomado Falcon due to its susceptibility to extinction due to its very restricted distribution

in the north-central part of Chihuahua. At the time of its discovery, it was expected that this

desert population, with adequate protection and management, would potentially colonize the

former breeding range in northern Mexico and the United States. The territorial occupation of the

Aplomado Falcon in the state of Chihuahua was documented for a period of 12 years by Macías-

Duarte et al (2016), under predominant conditions of drought. They found that 17 of 35 historic

nesting territories were converted to agricultural croplands, a red flag for the survival and

persistence of the species. The persistence of a few breeding pairs suggests that the population is

currently maintained by the high survival rates of adults rather than by reproduction. The same

authors mention that this trend, as well as the continuous destruction of the scarce high quality

habitat for the Falcon Aplomado, means the likely disappearance of the species in the

Chihuahuan Desert.

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Materials and Methods

The historical territories (Map 1) were visited once a month starting in January, searching

for Aplomado Falcons. In each visit, three monitoring techniques were applied, described below:

1. Observations from vehicle. For observation, a Vortex® spotting scope model

Skyline ED with 60x magnification was used. The spotting scope was placed in the truck

bed and observations were made 360° around the truck. During the observation with the

spotting scope, potential nesting structures were identified, such as yuccas, mesquites and

artificial structures such as windmills. The average duration at each observation station

varied from 15 minutes to 1 hour.

2. Reconnaissance on foot. After observing from the observation stations, staff

patrolled the territory on foot and searched for Aplomado Falcons within a radius of 1 km

from each potential nesting structure. During this reconnaissance, short-term observation

stations were set up with a spotting scope and binoculars.

3. Direct inspection of nesting structures. The inspection was carried out using a

mirror mounted on an extendable pole. All possible nesting structures identified from the

observation stations were inspected.

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Map 1. Location of the historic territories of Aplomado Falcons in Chihuahua

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Status of Aplomado Falcon territories

The following categories were used to classify activity in the Aplomado Falcon territories:

Active: Territories with active nests with eggs or chicks documented.

Occupied: Territories where the presence of breeding pairs was confirmed without

finding active nests.

Occupied without confirmation: Territories where the presence was recorded by ranch

staff, but not confirmed by direct observation of the IMC VS technician.

Inactive: Territories where no evidence of presence was found.

Results

From the months of January to July 2017, the 24 historic territories of the known

distribution of Aplomado Falcons in the state of Chihuahua were visited monthly (Table 1).

There were eight pairs of Aplomado Falcons, of which seven had active nests (Map 2). Of these

seven pairs, five produced 15 successful fledglings. These fledglings were 12 females and only

three males. Twelve fledglings were banded (Table 2, Photos 1 and 2).

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Table 1. Known territories and occupation status of Aplomado Falcon (Falco femoralis

septentrionalis) visited in the state of Chihuahua in 2017. The sign (-) indicates that the birds

were not encountered.

Municipality Ranch Territory Occupation status

Occupied Type of nest Production

Ahumada El 24 Hueso Yes Artificial Three

fledglings

Petrolero Yes Prosopis

glandulosa

1 egg

depredated

Caballo - - -

Noche

Buena

- - -

Ojos de San

Antonio

Ojos de San

Antonio

- -

Mennonite

colony El

Barreal

Barreal - - -

Mennonite

colony

Chivatito Yes High voltage

tower

Three

fledglings

El Sueco Rancho - - -

Oeste Yes Yucca elata Three

fledglings

Escondido - - -

El Venado Territorio

Nuevo

Yes Yucca elata Depredated 2

chicks; 1 egg

was collected

Chihuahua La Gregoria La Gregoria - - -

Coyamito Coyamito 1 - - -

Tolvaneras El 1 and El 4 - - -

El 15 El 15 - - -

5b 5b Yes - Adult pair

Coyame Galilea T4 - - -

Alegre - - -

Paloma La Paloma - - -

El Palomo Yes Artificial 3 fledglings

T4 Yes Yucca elata 3 fledglings

Yerboso - - -

Alpine Alpine - - -

Tosesihua Tosesihua - - -

Agua zarca Agua zarca - - -

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Map 2. Location of nests and breeding pairs of Aplomado Falcon (Falco femoralis septentrionalis) detected from June-September in

Chihuahua. Successful nests: 1: nest in El 24 Hueso, 2: nest in El Sueco Oeste, 3: nest in Chivatito, 4: nest in El Palomo, 5: nest in

T4. Depredated nests: 6: nest in El 24 Petrolero, 7: nest in El Venado. 8: Breeding pair in 5b.

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Table 2. Fledglings of Falco femoralis septentrionalis banded in the state of Chihuahua in

2017.

Nest Date Sex Age

(days)

Weight

(g)

Band

El Sueco June 26 female 17 350 5 red / W black

female 2 16 340 6 red / E black

male 1 17 190 8A green

El 24 Hueso May 14 female 2 26 405 K red / 6 black

male 26 290 4A green

female 24 420 K green / 4 black

El Palomo May 14 female 2 >32 410 C green / 4 black

female >32 430 D green / 3 black

female >32 415 W green / 2 black

T4 May 14 female 2 23 330 H green / 4 black

female 23 335 V green / 2 black

female 21 310 C red / 0 black

1 This male was banded on the right tarsus; all other male or female chicks on the left. 2 Indicates that a blood sample was taken.

Photo 1. Female Aplomado Falcon chick at least 32 days old banded in the El Palomo nest

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Photo 2. Close-up of band on male Aplomado Falcon chick 17 days old

Nesting structures utilized

Table 3 lists the different nesting structures used by the Aplomado Falcon pairs.

Four structures were natural, three Yucca elata (soaptree yucca) (Photos 4, 5 and 6) and

one Prosopis glandulosa (honey mesquite) (Photo 7) and 3 artificial, in a high voltage

transmission tower (Photos 8 and 9) and two artificial nesting platforms (Photos 10 and

11) installed for this purpose.

Reproductive Productivity

The five territories that were successful (Table 1) produced 15 fledglings (juveniles

capable of flying). The other territories did not produce juveniles that could be recruited to

the population. Total productivity, calculated as 15 juveniles divided amongst the 8 pairs

(occupied territories), is equal to 1.87 juveniles per occupied territory. The territories in

which their nests were depredated were El 24 Petrolero in a Prosopis glandulosa where we

were unable to determine the cause of the loss, since in a later visit the nest was simply

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found empty. The other depredated nest was in a new territory called El Venado in a Yucca

elata, where the chicks that had hatched were not detected and it could not be established

what had preyed upon the chicks. In this nest, an egg was collected for further analysis. The

total number of falcons detected was 31, with 16 adults and 15 fledglings.

Additional to monitoring, casual sightings were documented during field visits of

other conservation and restoration projects. For example a subadult female was detected in

Rancho San Luis, however, not being banded, we cannot differentiate it from the subadult

female that is the mate in the territory of El Venado, so it is possible that it is the same

female.

Table 3. Aplomado Falcon nests in Valles Centrales, Chihuahua, 2017 breeding season.

territory nest

success fledglings banded female male nesting structure

El 24 Hueso yes 3 yes 2 1 nesting platform

El 24

Petrolero no 0 0 0 0

Prosopis

glandulosa

Chivatito yes 3 no 2 1

high voltage

transmission

tower

El Venado

(Ejido) no 0 0 0 0 Yucca elata

El Sueco yes 3 yes 2 1 Yucca elata

The Palomo yes 3 yes 3 0 nesting platform

T4 yes 3 yes 3 0 Yucca elata

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Photo 4. Aplomado Falcon nest and fledglings in Yucca elata in territory T4

Photo 5. Aplomado Falcon nest and fledglings in Yucca elata in the territory El Sueco Oeste

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Photo 6. Unsuccessful nest and breeding pair of Aplomado Falcon in Yucca elatta in the territory

El Venado. The largest yucca contained the nest that was later depredated.

Photo 7. Unsuccessful Aplomado Falcon nest in Prosopis glandulosa in the territory El 24

Petrolero that was depredated.

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Photo 8. High voltage transmission tower that contained Aplomado Falcon nest in the territory

Chivatito

Photo 9. Aplomado Falcon nest and fledglings in high voltage transmission tower

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Photo 10. Artificial nest and Aplomado Falcon fledglings in the territory El Palomo.

Photo 11. Artificial nest and Aplomado Falcon chicks in the territory El 24 Hueso.

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Conclusions and recommendations

1. In Aplomado Falcon monitoring this year, a population increase was found relative to last

year (31 vs. 22 individuals). The productivity of the breeding pairs increased from 0.44

fledglings per occupied territory in 2016 to 1.88 in the current period. Therefore it is

recommended to continue with the monitoring program and continue to place artificial

nesting structures, because when used, they provide a good opportunity for the chicks to

survive to develop into adults.

2. The banding and telemetry of individuals allowed us to detect a new territory, so it is

recommended to continue with the banding program of all chicks and adults as possible.

3. The natural population of the Aplomado Falcon in the state of Chihuahua remains in

grassland habitat, however, territories are still lost due to land use change, an example of

which is the Chivatito Norte nest that was located in a transmission tower surrounded by

developing agricultural fields, so it is necessary to delve into the problem of land use

change and look for measures that slow down the expansion of the agricultural frontier.

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Literature Cited

Keddy-Hector, D. (2000). Aplomado Falcon. In The Birds of North America Online (Poole, A.,

Poole, A.)Poole, A.s). Cornell Lab of Ornithology; Retrieved from the Birds of North

America Online: http://bna.birds.cornell.edu.bnaproxy.birds.cornell.edu/bna/species/549,

Ithaca, N. Y.

Ligon, J. S. (1961). New Mexico birds and where to find them. University of New Mexico Press,

Albuquerque, New Mexico

Macías-Duarte, A. 2002. Éxito Reproductivo, Presas Potenciales y Hábitat del Halcón Aplomado

Falco femoralis septentrionalis Todd en Chihuahua, México. Master's thesis, Universidad

Autónoma de Chihuahua, Chihuahua, Chihuahua, México.

Macías-Duarte, A., A. B. Montoya, W. G. Hunt, A. Lafon-Terrazas, and R. Tafanelli (2004).

Reproduction, prey, and habitat of the Aplomado Falcon (Falco femoralis) in desert

grasslands of Chihuahua, Mexico. Auk 121:1081-1093.

Macías-Duarte, A., A. B. Montoya, C. E. Méndez-González, J. R. Rodríguez-Salazar, W. G. Hunt,

and P. G. Krannitz (2009). Factors influencing habitat use by migratory grassland birds in

the state of Chihuahua, Mexico. The Auk 126:896-905.

Macías-Duarte, A., A. B. Montoya, J. R. Rodriguez-Salazar, A. O. Panjabi, P. A. Calderón-

Domínguez, and W. G. Hunt (2016). The imminent disappearance of the Aplomado

Falcon from the Chihuahuan Desert. Journal of Raptor Research 50:211-216.

Mendez-Gonzalez, C. E. 2000. Abundancia relativa y biomasa de aves de pastizal dentro de

territorios de halcones aplomados (Falco femoralis) en Chihuahua, Mexico. M.S.,

Universidad Autónoma de Chihuahua, Chihuahua, Mexico

Montoya, A. B. 1995. Breeding biology of Aplomado Falcons in desert grasslands of Chihuahua,

Mexico. Master's thesis, New Mexico State University, Las Cruces, New Mexico.

Montoya, A. B., P. J. Zwank, and M. Cardenas (1997). Breeding biology of Aplomado Falcons in

desert grasslands of Chihuahua, Mexico. Journal of Field Ornithology 68:135-143.

Mora, M. A., C. Baxter, J. L. Sericano, A. B. Montoya, J. C. Gallardo, and J. R. Rodriguez-

Salazar (2011). PBDEs, PCBs, and DDE in eggs and their impacts on aplomado falcons

(Falco femoralis) from Chihuahua and Veracruz, Mexico. Environmental Pollution

159:3433-3438.

Mora, M. A., A. B. Montoya, M. C. Lee, A. Macias-Duarte, R. Rodriguez-Salazar, P. W.

Juergens, and A. Lafon-Terrazas (2008). Persistent environmental pollutants in eggs of

aplomado falcons from Northern Chihuahua, Mexico, and South Texas, USA.

Environment International 34:44-50.

Rodriguez-Ruiz, E. R., J. F. Gomez-Rodriguez, J. Trevino- Carreon, S. Teran-Trevino, F. A.

Enriquez-Medina, A. Sanchez-Gonzalez, H. A. Garza-Torres, C. Paramo-Mendoza, and H.

Gomez-Ramirez (2012). Nuevos avistamientos de aves para Tamaulipas, Mexico. Huitzil

13:162-168.

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Appendix: Research permit from Dirección General de Vida Silvestre

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