by Dina Dechmann
Climate variability affects the impact of parasitic flies on Argentinean forest birds
L.R. Antoniazzi, D.E. Manzoli, D. Rohrmann, M.J. Saravia, L. Silvestri & P.M. Beldomenico, 2011, J. of Zoology 283: 126-134
During my PhD I worked on tropical bats that excavate and inhabit live termite nests and one of the conclusions I drew from my data was that high and stable temperatures inside the termite nests was a major reason justifying this time and energy consuming roost choice. However, almost every time I presented these data there was at least one critical voice in the audience doubting that the temperature difference I found (about 2 degrees Celsius more than maximum ambient temperature) would make a difference for an animal in the tropics “where it’s hot anyway”.
This paper by a group of collaborators from Argentina and the US does not investigate a tropical system, but a Pampean temperate one. However, the study was conducted during the local spring and summer when it’s either “hot” or “even hotter”. Looking at an impressively large number of bird species as well as nests they found an important effect of climate, precipitation and temperature on bot fly infestation of nestlings, particularly in passeriforms. This in turn significantly influenced nestling mortality. In other words, higher temperature and more rain meant higher parasite infestation and nestling mortality.
Climate change is expected to result in stronger temperature changes in regions at mid- to high-latitudes and those are the regions studied most intensively for predicting the effects of climate change. However, recent work beautifully exemplified by a paper published in Nature last year by Dillon, Wang and Huey, shows that this may be a dangerous approach. Ectotherms that live at low latitudes are also adapted to more narrow temperature ranges and consequently, much smaller temperature changes have much stronger effects here. Studies like the one published last month in Journal of Zoology by Antoniazzi and co-authors, indicate that this may also be true for warm blooded vertebrates and I concur with the authors that many more studies are needed to understand and predict the effects that climate change may have on these climatic regions that are so important for global biodiversity.