Thought I would post some of my own work!
This is a poster presentation for the Arizona Field Ornithologists Meeting
October 5, 2013 in Sierra Vista, AZ.
PRELIMINARY FINDINGS: THE DIET OF
ARIZONA’S GOLDEN EAGLE
*Losee, M. J.,
Antioch University New England
Jacobson, T. Licence, K. and K. McCarty,
K.
Arizona Department of Game and Fish
In Arizona, the
Golden Eagle (Aquila chrysaetos) has been largely unstudied. In 2011,
Arizona Game and Fish Department (AZGFD) began a two-year nest survey for cliff
nesting Golden Eagles throughout the state. Golden Eagle occupancy and diet
assessments began in 2013. During the 2013-nesting season, we collected prey
remains from six active Golden Eagle nest in the northern region of the state.
The number of prey items ranged from 3 to 29 with the number of different
species ranging from 2 to 6. The Black-tailed Jack Rabbit (Lepus
californicus) was the only prey species found in all six nests and the
highest percentage (33-81%) of total species found in each nest as well as
contributing to the highest biomass (2.7-5.9kg) for each nest. The two
heaviest, single prey species were a Pronghorn Antelope (Antilocapra
americana) fawn (3kg) and a juvenile Gray Fox (Urocyon cinereoargenteus)
(3.2kg). The more unique prey species were snake, an adult Raven (Corvus
corax), domestic feline and a juvenile Pinyon Jay (Gymnorhinus
cyanocephalus). The nest with most diversity of prey species (6) was the
only nest with two nestlings.
These
preliminary findings revealed important information pertaining to the dietary
habits of Golden Eagles nesting in Northern Arizona. The results showed that
jack rabbits (Lepus spp.) were the dominant prey species for nesting
pairs. This was consistent with both (Eakle and Grubb 1986,
Stahlecker et al. 2009),
in which both studies documented at least 50% of the prey species were jack
rabbits. In this study, as well as (Eakle and Grubb 1986,
Stahlecker et al. 2009),
the Rock Squirrel (Otospermophilus
variegatus) was the second most abundant prey
species. There was a lower than expected amount (1%) of Prairie Dog (Cynomys
spp.) remains. This could have been just a factor
of what was present in the nest at the time of collection or could show a
decrease in availability for this species. Stahlecker et al. (2009)
documented 8% of prey species were prairie dogs, while (Eakle and Grubb 1986)
documented none. This information as well as data collected from next year’s
nesting season will help describe the dietary and foraging requirements for
Golden Eagle pairs nesting in Arizona. These requirements coupled with
occupancy data will assist AZGFD to generate better conservation action and
policy recommendations.
*Presenting author
Prey Species
|
Number of Individuals
|
Weight (kg)
|
Biomass (kg)
|
Proportion of Individual Species (%)
|
Proportion of Biomass (%)
|
Jack Rabbit
(Lepus
californicus)
|
46
|
9.1
|
124.2
|
68
|
83
|
Rock Squirrel
(Spermophilus variegatus)
|
10
|
0.66
|
6.6
|
15
|
4
|
Desert Cottontail Rabbit
(Sylvilagus audubonii)
|
3
|
1.2
|
3.6
|
4
|
2
|
Raven (Corvus corax) - Adult
|
1
|
1.3
|
1.3
|
1.5
|
1
|
Pronghorn Antelope - Fawn
(Antilocapra americana)
|
1
|
3.3
|
3.3
|
1.5
|
2
|
Feline domestic -
sub adult
|
1
|
1
|
1
|
1.5
|
1
|
Prairie Dog (Cynomys spp.)
|
1
|
1.5
|
1.5
|
1.5
|
1
|
Duck (Spp?)
|
1
|
1.2
|
1.2
|
1.5
|
1
|
Raven/Crow (Corvus spp.)
|
1
|
0.9
|
0.9
|
1.5
|
1
|
Pinon Jay - Juvenile
(Gymnorhinus cyanocephalus)
|
1
|
0.1
|
0.1
|
1.5
|
1
|
Rabbit (Lagomorpha)
|
1
|
1.95
|
1.95
|
1.5
|
1
|
Gray Fox - Juvenile
(Urocyon cinereoargenteus.)
|
1
|
3.2
|
3.2
|
1.5
|
2
|
Total
|
68
|
25.41
|
148.9
|
These results are from all six nests
for the 2013 nesting season.
|
Literature Cited
Eakle, W. L. and T. G. Grubb. 1986. Prey remains from
Golden Eagle nests in central Arizona. Western Birds 17:87-89.
Stahlecker,
D. W., D. G. Mikesic, J. N. White, S. Shaffer, J. P. DeLong, M. R. Blakemore,
and C. E. Blakemore. 2009. Prey remains in nests of Four Corners Golden Eagles,
1998-2008. Western Birds 40:301-306.