Many hummingbird species are struggling with declining populations, and one British Columbia research scientist thinks she knows why: Exposure to pesticides.
As Canadian Press first reported last summer, Christine Bishop of Environment and Climate Change Canada began her research in 2015 as part of a five-year study. She is now roughly halfway through, and early indicators are that insecticides may be contributing to the die-off, just as many suspect they contribute to colony collapse disorder in bees.
While other factors have also been discussed, including climate change effects to how and when plants bloom and habitat loss, Bishop wanted to test her theory that insecticides might be at least partially responsible. Toward that end, she and her team have spent the last few years collecting urine and feces samples from the birds, which they have then tested for insecticide contamination.
As she told CBC,
“No one has ever measured pesticides in hummingbirds before. So we decided to try it…It turns out, to our surprise actually, that the birds are obviously picking up pesticides in their food, which can be nectar and also insects.”
More concerning is that the pesticide levels are quite high, three parts per billion, in the sampled urine.
As Bishop noted, there’s still more studying to be done:
“Now what does it mean? Right now we’re just understanding what the level of exposure is, and then how is it affecting the population, well that’s part of the population dynamics.”
In particular, she and her research team are focused on Fraser Valley in southern British Columbia, a rich agricultural region and a core home area for the rufous hummingbird. A small, feisty, red-throated bird, the rufous spends summers in British Columbia, Alaska, and the Pacific Northwest, migrating to the Southwest each winter.
And there’s reason for concern when it comes to the rufous. Annual birding surveys show that between 1996 and 2013, the Pacific Coast population dropped steady, nearly 3 percent per year. And other hummingbirds are similarly declining in numbers.
As a result, Health Canada is re-evaluating the use of imidacloprid, a neonicotinoid insecticide used both in agriculture and in tick treatment for cats and dogs.
Like bee loss, insecticides may not be the only factor, but evidence continues to mount that it is almost certainly a factor. Bishop’s study, too, won’t be done for several more years.
Still, there’s reason for concern. Rufous numbers continue to decline even as efforts are made to help them.
Bishop can’t help but wonder:
“But what’s interesting about this is … more and more people are putting out feeders, yet the population is still declining.”