Posted by Carmela Espanola & Stuart Marsden
First, the whole group would like to congratulate Carmela Espanola on her recent PhD conferment. Her PhD, funded by Loro Parque Fundacion, focused on parrots and other large frugivores in the dwindling forests of Luzon. There are several important aspects to this PhD which we hope to publish in the future. This potentially very important paper has just been published.
Large frugivorous (fruit-eating) birds are incredibly important. People know them, eat them, and keep them as pets. A huge number are threatened worldwide. Crucially, most provide irreplaceable ecosystem function by dispersing the seeds of tropical trees.
Carmela and her team surveyed 25 frugivore species using ‘distance sampling’ along nearly 500 km of line transects at 14 sites across the island of Luzon. Most frugivores seemed at least to be hanging on at most forested sites – although one species, the Green Racquet-tail, a lowland parrot has been recorded at only seven sites in the last ten years. Still more alarming was the absence of large parrots from most sites with apparently intact habitat surveyed. Worryingly, even where present, large parrots occurred at much lower densities than related species in similar habitat elsewhere in Southeast Asia.
She estimated population sizes for species in five reserves selected from the current
protected area network. For six species, including four of six parrots, largest populations in any reserve in Luzon numbered <1,000 individuals, and nearly one-third of all populations in reserves were less than 100. If we consider that animals might have a minimum viable population (MVP) below which they are likely doomed to extinction, then we can try to look into the future to see which frugivores will still be around in which reserves. At MVPs of 500, frugivore communities in all but 2–3 of the largest reserves on Luzon are not expected to survive.
Although many frugivores are good fliers that can disperse between widely separated sites, we nevertheless predict that without stricter species and site protection a major collapse of frugivore communities will occur across Luzon. This will have very serious implications for ecosystem functioning of the forests themselves and for indigenous communities dependent on the island’s forests to live.
A grant that Carmela recently secured from the National Science Research Institute of the University of the Philippines will allow further work on cavity-nesting frugivores where breeding ecology will be investigated and nest availability/competition will be assessed at two adjoining reserves in western Luzon. These are the only reserves in Luzon where a thriving population of the Green Racquet-tail, a threatened Luzon-endemic parrot, is still found. Volunteers with experience in tropical ecological research and training in tree-climbing are welcome to join the fieldwork from April-May 2014 (email firstname.lastname@example.org).
Thanks to Adrian Constantino of Birding Adventure Philippines (parrot photos), Chris Johns (hornbill photo) and Arnel Telesforo (tree photo) for letting us use their stunning images.
Carmela Espanola's PhD was funded by Loro Parque Fundacion