Helen Esser and Yorick Liefting from Wageningen University, the Netherlands, are studying the community composition of ticks and their mammalian hosts in the Barro Colorado Nature Monument. More specifically, they want to now how mammal density and diversity impacts tick density and diversity. In order to do so, they are sampling various islands and peninsulas surrounding BCI by placing remote cameras and collecting ticks using the drag-sampling method. Island size and isolation are among the most important determinants of species richness, and it is a well documented fact that ecosystem fragmentation causes a decline in species richness. Therefore, a fairly large range in mammal abundance and diversity is expected between the numerous islands and peninsulas of the BCNM, which vary both in size and isolation from adjacent forests. With a total area of 1600 ha, BCI is the largest of the islands in the Gatun Lake and most species of mammals which were there before the creation of the canal are still there. Some species have disappeared from the island, such as crab eating raccoons, rabbits, olingos and owl monkeys. Other species such as pumas and jaguars are able to swim on and off the island, so even though they are not permanent residents, the close proximity of BCI to the mainland allows these species to reach the island. One of the islands Helen and Yorick are working on, Frijoles Island (65.5 ha), is connected to the mainland by the Panama Canal railroad.
It appears that this rail link is being used by predatory mammals to get to the island. In one camera location, Helen and Yorick caught a pair of agoutis in an intimate moment. At this same site, they also captured photos of an ocelot and a yaguarundi! Given the size of the island, these cats are probably not permanent residents, but are using the rail link to move on and off the island. In addition to these exciting photos, they also found a species of rabbit which is no longer found on BCI.