Lucía Vargas and Andrew Whitworth
Linked paper: Secondary forest is utilized by Great Curassows (Crax rubra) and Great Tinamous (Tinamus major) in the absence of hunting by A. Whitworth, C. Beirne, E. Flatt, R.P. Huarcaya, J.C.C. Diaz, A. Forsyth, P.K. Molnár, and J.S.V. Soto, The Condor: Ornithological Applications 120:4, November 2018.
In one of the most biologically diverse rainforests of the world, the Osa Peninsula of Costa Rica, curassows and tinamous are thriving by hiding from hunters in protected, regenerating forests. These forests were once grasslands and disturbed forests that were hunted out. We have found that conservation efforts by the nonprofit group Osa Conservation (www.osaconservation.org) have been efficient for protecting these stunning gamebirds.
Game birds are important seed dispersers, control insect populations, and are food for many mid-level and apex predators. They provide social and economic services and are a source of protein, materials, and economic income from birding tourism. However, deforestation and hunting are leading causes of declines in populations of game birds such as the Great Curassow (Crax rubra) and the Great Tinamou (Tinamus major). The Great Curassow, for example, had lost 69% of its original habitat by 1977, and hunting was responsible for greatly reducing many populations, to the point of local extirpation in some regions. We wanted to know how valuable recovering habitats can be for such species, providing that hunted is controlled.
The field work to set up 60 camera traps during the very hot dry season was intense. It can be tricky to determine what factors play a role in habitat choice, but we had an ideal study site. Our grid covered a relatively small protected area (free from hunting) that comprises several different habitat types: old-growth primary forest, naturally regenerating secondary forest, recovering secondary plantation forests, and active agricultural land. Moreover, we analyzed the influence of roads, rivers, elevation, and whether cameras were located on or off trails, all of which are known to influence the distribution of rainforest wildlife.
Both bird species chose to use secondary growth forest frequently, despite being described in other studies as primary forest specialist species. This is likely due to the eradication of hunting since the establishment of Osa Conservation in 2002, the close proximity of remaining old-growth forest tracts, and the fact that the regenerating forests have had over 45 years to recover.
One surprising result from our data was that Great Curassows are more likely to be seen near roads. This makes sense when we consider that they are likely benefitting from a higher abundance of fruiting trees, but they must be careful, because this could also result in what is known as an ecological trap. If hunting were to return, roads would provide easy access for hunters. On the other hand, although the tinamous utilized all types of forest, they very clearly avoided agricultural land. Even the forest strips in farm areas are not sufficiently safe and cozy for the Great Tinamou—they like it cool, dark, and well-connected.
Our study demonstrates the significance of protecting wildlife from hunting through understanding spatial behavior. What would the results be like at another site? In a place with no source population nearby to allow for natural recolonization as the forests recover, could we reintroduce and reestablish these species once hunting has been controlled?
Their importance as rainforest seed dispersers will affect the pathway of regeneration and growth of secondary forests, and their presence will also provide food for predators like ocelots and margays, assisting their recovery as well. “Secondary” forests don’t mean second-rate habitat—instead, they mean that wildlife and people have a second chance.