Three primary threats—global climate change, invasive species, and habitat destruction—were identified at the April 2009 WHP Workshop as being of highest concern for hummingbirds. Perhaps, the greatest threats to hummingbird survival is the effect of changing climates on flowering phenology, where even minor changes in climate can produce large changes in nectar availability and in blooming dates that may decouple the mutualism between hummingbirds and the plants they pollinate. Loss of forest habitat either by direct destruction or alteration by invasive plants is also of great concern. Modification of hummingbird habitats continues to increase and will likely change the distribution and viability of hummingbird communities, as well as exacerbate the impacts of climate change on plant phenology (e.g., Bazzaz 1998, Gienapp et al. 2005).
Bazzaz, F.A. 1998. Tropical forest in a future climate: changes in biological diversity and impact on the global carbon cycle. Climatic Change 39: 317-336.
Gienapp, P., L. Hemerik and M.E. Visser. 2005. A new statistical tool to predict phenology under climate change scenarios. Global Change Biology 11: 600-606.