Tuesday, 22 April 2014

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).  


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.

Wednesday, 16 April 2014

The hunt for Philippine Ducks

Posted by Beth Roberts and Carmela Española

Beth has just returned from Philippines where she attended the Wildlife Conservation Society of the Philippines conference, and, together with Carmela Española, started a project looking at distribution, abundance and hopes for the little-studied Philippine Duck.

Conversion of wetlands to agriculture is placing many species under increasing threat of extinction (Photo: Beth Roberts)
The Philippines is among 25 megadiversity hotspots in the world and has been placed within the two ‘hottest of hotspots’ owing to its high levels of endemism (>47% of vertebrates and >76% plants). However, this rich biodiversity do not translate into increased measures of conservation action, and 33% of the country’s 181 endemic birds are threatened, the second highest total of any country. One such species is the threatened Philippine Duck Anas luzonica. My PhD research to date examines the biases in published wildfowl demographic research (see http://stuartmarsden.blogspot.co.uk/2014/01/macro-demography-and-conservation-of_18.html) and highlights the importance of conducting studies in areas with limited knowledge, such as the Philippines.

Philippine Duck Anas luzonica (Photo: Arman Asilo)

To gather vital basic ecological and habitat requirements of the Philippine Duck, I visited the Philippines with funding received from two MMU awards (Careers and Development award and an RKE Conference award). Dr Carmela Española and I visited four wetland habitats, two of which are Ramsar sites. Hunting continues at all sites; however, at the Ramsar sites, prosecutions for Philippine Duck hunting had been made.

Candaba Bird Sanctuary (Photo: Beth Roberts)

We first visited Candaba Marsh, Luzon (categorised as an IBA); an important wetland site for resident waterbirds and migratory species with recorded sightings of Baer’s Pochard Aythya baeri (Critically Endangered) and Streaked Reed-warbler Acrocephalus sorghophilus (Endangered). Candaba Bird Sanctuary, a 100-hectare private property of the former mayor Jerry Pelayo, acts as a wetland fragment in an agricultural landscape and is under threat from agriculture expansion.

Other species, such as Clamorous Reed-warbler Acrocephalus stentoreus
are found in the wetland habitats (Photo: Beth Roberts)
Large numbers of Wandering Whistling-duck Dendrocygna arcuata and Philippine Duck were present, along with many other wetland bird species. We recorded over 300 Philippine Ducks at the site and, whilst interviewing local farmers, we observed a man standing on a water buffalo collecting eggs, possibly Philippine Duck eggs.

Man stood on a carabou collecting birds’ eggs in the marsh (Photo: Beth Roberts)

The ducks were flushed from the disturbance (Photo: Beth Roberts)
We also conducted a site visit to the river mouth at Subic Bay, Luzon, which has historically recorded 400 Philippine Ducks congregating in a large group in the mangroves. We found no ducks, but we gathered valuable nesting and habitat data from local people.

The mangrove area at Subic Bay (Photo: Beth Roberts).
Our third site was Naujan Lake (14,568 ha) in Mindoro, designated a Ramsar site, and the fifth largest lake in the Philippines. The lake supports large numbers of ducks and other waterbirds.. The duck may occur at low densities due to the availability of many suitable wetland habitats or as a consequence of increased hunting pressure from the local people that live next to the lake. 

Naujan Lake, Mindoro Island (Photo: Beth Roberts).

The final site was Las Piñas-Parañaque Critical Habitat and Ecotourism Area (175 ha), a coastal wetland within Metro Manila, and designated a Ramsar site. The area supports large numbers of resident and migratory birds (including the ‘Vulnerable’ Chinese Egret Egretta eulophotes) and is a breeding site for the Philippine Duck. We found 25 Philippine Ducks using the shallow lagoons within the mangrove forest.

The area consists of many small lagoons, with dense vegetation surrounding the pools. Permits are required to visit the area (Photo: Beth Roberts)
 The Asian Waterbird Census (AWC) has been conducted in the Philippines since 1990. Totals of 24,585 Philippine Duck were counted at 71 sites in 2013, 17,491 at 67 sites in 2012, and 20,337 at 65 sites in 2011. One criterion for Ramsar designation is that a wetland site supports 1% of a given bird’s global population. Using this criterion, many more Philippine wetlands should be designated as Ramsar sites. It is critical to: 1) assess the accuracy of the AWC data; 2) determine whether better wetland protection translates into better species protection; 3) conduct surveys at key wetland sites to assess the abundance and habitat use of the Philippine Duck and other wetland bird species; 4) gather information on other threatened species, such as the Vulnerable Sarus Crane Grus antigone and Chinese Egret, the Near Threatened Spot-billed Pelican Pelecanus philippensis, and the Data-Deficient species such as the Brown-banded Rail Lewinia mirifica; and, 5) assess hunting pressure and egg collection rates.

Chinese Egrets (Photo: Drakesketchit)
We plan to raise funds to conduct research on Philippine wetland bird species to provide information on abundance and habitat requirements and evidence to support better protection for important wetland sites throughout the Philippines. We are applying for small research grants and also doing crowdfunding- Please see our campaign at - http://igg.me/p/753968/x/7124691, if you would like to make a private donation.

If you would like to know more about the project please contact – Beth Roberts at b.roberts@mmu.ac.uk. Collaborating on the project are Dr Carmela Española, University of the Philippines, Dr Stuart Marsden, Manchester Metropolitan University and Dr Matt Geary, University of Chester.

Wednesday, 9 April 2014

Cattle grazing and raptors in a Peruvian protected area

Posted by Renzo Piana and Stuart Marsden

Renzo finished his PhD with us a couple of years ago on the ecology and conservation of diurnal raptors in the Tumbesian region of northern Peru. Here we talk about the latest publication from his PhD which looks at the influence of cattle grazing pressure on raptors.

Uncontrolled cattle grazing is frequent in protected areas across the tropics, but its effect on habitat structure and biodiversity is poorly known. From April to December in years 2008 and 2009, I surveyed raptors presence and vegetation structure in 70 one km² square plots randomly positioned in North West Biosphere Reserve (NWBR), a 120,000 ha protected area that includes the Cerros de Amotape National Park, Tumbes National Reserve and buffer areas in the core of the Tumbesian Endemic Zone. The NWBR holds many Tumbesian endemic bird species and at least 36 diurnal raptor species (50% of all those occurring in Peru), including the ‘Endangered’ Gray-backed Hawk, are present here.

Map of the Tumbesian Endemic Zone (adapted from Best and 
Kessler 1995) and detail of study area (in the circle).

Given the amount of forest conversion into cattle pastures, particularly in the Tumbes National Reserve, I estimated cattle density in the protected areas - this was done by counting the density of cattle dung, estimating the number of dungs produced by an individual cow, and the decay rate of dungs. In Ecuador, conversion of Tumbesian forests into cattle pastures and agricultural areas have seriously reduced forested areas west of the Andes. It is estimated that less than 10% of these forest remain (Dodson and Gentry 1991). Besides direct forest removal, trampling of forest floor and consumption of palatable plant species close to ground level affects understory, which in turn, might impact community structure of wildlife species, including those that are preferred prey for raptors.

Cattle grazing and its impact in the Tumbes National Reserve (Photos: Renzo Piana).
To examine this, we used generalized additive models (GAMs) to examine the precise relationships between cattle grazing intensity, vegetation structure, and raptor occurrence and richness across the NWBR. Cattle grazing was widespread and intensity was negatively correlated with average canopy height and percentage of vegetation cover at 5-15 m. 

In the NWBR, presence of some range-restricted species like the Gray-backed Hawk (left) and Black Hawk-Eagle (right) decreased with increasing cattle density (Photos: Renzo Piana).

Raptors were influenced by cattle density but they were probably more strongly influenced by canopy and sub-canopy characteristics. We also found that raptor species responded differently to increasing cattle ‘density’: presence of species that hunted or searched for food in open habitats (i. g. Short-tailed Hawk, King Vulture) or preferred edge habitats (Harris´s Hawk) increased with cattle density, while presence of range restricted species that hunted from perches (Black Hawk-Eagle), and declining species (Gray-backed Hawk) decreased. 

Abundance of species that occurred in open or edge habitats such as the King Vulture (left) and Harris´s Hawk (right) increased with cattle density (Photos: Renzo Piana).

Moderate cattle densities (20-60 cows per sq km) may actually benefit some raptor species and help to maintain the high raptor diversity in the study area. However, given the high rates of forest that already have been cleared, Tumbes National Reserve authorities should act to reduce cattle densities in some areas, which can exceed 120 cows per sq km, and that seriously affect some key raptor species. Additionally, cattle grazing inside the Cerros de Amotape National Park should be strictly controlled.


Dodson, C.H., and A.W. Gentry. 1991. Biological extinction in western Ecuador. Annals of the Missouri Botanical Garden 78: 273-295.

Best, B., and M. Kessler. 1995. Biodiversity and conservation in Tumbesian Ecuador and Peru. BirdLife International, Cambridge

Renzo's PhD was funded by the Peregrine Fund