Counting Andean Condors at feeding stations

Posted by Diego Mendez and Huw Lloyd

Conservation Biology Masters student Diego Mendez has been awarded a research grant from the Peregrine Fund for his proposed MSc thesis research entitled ‘Designing a standardised photographic mark-recapture method for estimating population densities of Andean Condor using feeding stations’. Diego, a graduate of the Universidad Mayor de San Simón, Cochabamba, Bolivia, has been studying Andean Condors in Bolivia with Birdlife International partner organisation Armonia since 2012. He has been studying at MMU since September 2013 and will be undertaking his fieldwork in June 2014 with supervision from Dr Huw Lloyd and Dr Stuart Marsden.

Diego photographing Condors

Andean Condor populations are declining throughout their range due largely to human persecution and reduced food availability. Globally, the species is listed as Near-threatened, but in Bolivia, the species is listed as Vulnerable. The species is notoriously difficult to survey due to its preference for the rugged topography of Andean habitats and the large distances individuals are able to travel each day. This has resulted in a lack of population data for the species. Recent studies from the Apolobamba Mountains in NW Bolivia have used feeding stations to attract and photograph individual condors (Ríos-Uzeda & Wallace 2007). This has proven to be a successful survey technique whilst also providing data on Andean Condor population structure.

Above - Andean Condor is currently listed as 'Near-threatened; Below - typical Condor habitat (Photos: Diego Mendez)

Natural markings on Andean Condors will enable Diego to reliably identify birds in different sex and age categories. Adult males are easily distinguishable from females by their crests and black eyes which females lack. Adult condors differ from sub-adults in having conspicuous white secondary feathers, and juveniles are brown in colour, with no white secondary or neck feathers. Adult males are also recognisable from each other based on differences in the shape and size of their crests, and the wattle-like skin-folds.

Above - Adult male Andean Condor, and Below - females (Photos: Diego Mendez)

Using photographs from the feeding stations in a ‘mark-recapture’ analysis has potential to be a useful survey technique for the species throughout Bolivia and neighbouring Andean countries. With additional funding from the British Ornithologists' Union and the Neotropical Bird Club, Diego plans to expand on this earlier study by creating feeding stations at over 30 different feeding station locations sited at standardised distances (25, 50 and 100 km) from each other throughout the eastern Bolivian Andes. Photographs will be be taken from a hide constructed at each feeding station from 07h00 to 18h00 for periods of five days. This will enable Diego to obtain reliable estimates of density and accurate observations of condors, and comparisons of re-sighting probabilities of photographed Andean Condors at different distances. As a result, Diego’s research may also help key areas for the conservation of the Andean Condor population in Bolivia.

Adult males are individually recognisable through careful examination of the shape and size of their crests, and the wattle-like skin-folds (Photo: Diego Mendez).  

References

Ríos-Uzeda, B. and R.B. Wallace. 2007. Estimating the size of the Andean Condor population in the Apolobamba Mountains of Bolivia. J. Field Ornithol. 78:170-175

Diego’s Masters project will be done in conjunction with Armonia and is funded by the Peregrine Fund, British Ornithologists Union and Neotropical Bird Club.