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Leal, Yozora – HOME RANGE CHARACTERISTICS OF BREEDING SAKER FALCONS (FALCO CHERRUG) AT ARTIFICIAL NEST SITES IN CENTRAL MONGOLIA

Tadehara with saker falcon

Thesis Abstract:

Understanding the movements of saker falcons (Falco cherrug) is directly relevant to the success and overall conservation efforts of this endangered species, as it is essential to develop an understanding of the space requirements the falcons need to successfully reproduce. This thesis documents my investigations of saker falcon home ranges in an artificial nest project in the steppe of central Mongolia. This research is part of a larger research project, which is designed to provide information on the movements and breeding success of saker falcons and in large to study the population genetics and population recruitment across Mongolia.

I used data collected from breeding adult saker falcons in the artificial nesting area in 2009 and 2010 to determine home range characteristics.  A total of 10 (n=10) breeding adults were evaluated with two (n=2) returning in 2010.  Using 22 g argos/global positioning system (GPS) solar platform transmitter terminal (PTT) units, I tracked their movements and estimated their home ranges using the Brownian bridge movement model (BBMM) and then mapped them in ArcGIS.  These home range estimates were defined at 50% (core home range extent) and 95% (total home range extent).

Home range areas ranged from 7.05 km2 to 4,365 km2 (mean = 697.74 km2) using 95% BBMM, and from 0.78 km2 to 546.39 km2 (mean = 69.78 km2) using 50% BBMM. No statistically significant differences in area were found between male or female home ranges (50%BBMM – t= -0.855, P= 0.431, 95%BBMM – t= -0.798, P= 0.459).  Overlap between two home ranges was calculated on a scale of 0-1, the smaller the value, the less overlap between home ranges. Most values calculated were small, indicating minimal overlap (only 1 value was above 0.5 for 50% BBMM). This supports my hypothesis that the falcons may exhibit territoriality with minimal overlap between home ranges.  However, male and female home ranges did not differ as I predicted due to different sex roles during the breeding season.