VANCOUVER—Some species of North American hummingbirds are in severe decline and a British Columbia research scientist says one possible cause might be the same insecticide affecting honey bees.
Christine Bishop, with Environment and Climate Change Canada, said researchers started looking at a variety of factors that may be responsible—ranging from habitat loss to changes when plants bloom.
To try and find some answers, researchers began collecting urine and feces from the birds for testing.
“No one has ever measured pesticides in hummingbirds before so we decided to try it,” Bishop said in an interview.
“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.”
Bishop said the concentration found in the urine is relatively high at three parts per billion.
“Now what does it mean?" she asked. "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.”
Her research is focused in the agricultural regions in the Fraser Valley and southern B.C.—the core area for the rufous hummingbird.
The rufous is a feisty, red-throated bird that weighs about as much as a nickel and spends its summers in B.C., Alaska, and the Pacific Northwest states, then migrates to the southern U.S. and Mexico.
The testing doesn't harm the birds. Researchers hang a net over a feeder and then lower it like a drape when the bird comes to feed.
Because the hummingbird constantly is processing nectar, it also constantly is expelling it, and Bishop said by the time they are banded, the bird likely has expelled urine and feces to test.
The annual breeding bird survey shows that between 1966 and 2013, the rufous population on the Pacific Coast dropped an average of 2.67 percent per year.
The survey said the Allen's and broad-tailed hummingbirds also were in decline.
Health Canada is re-evaluating the use of imidacloprid, a neonicotinoid insecticide used in on a large number of agricultural crops and at home on fleas or ticks on cats and dogs.
Health Canada said it is aware of Bishop's work and will consider information she passed on during a consultation period as part of its re-evaluation.
Health Canada expects to publish its findings in 2018.
Bishop is two years into a five-year study, and said the next question that needs to be answered is whether pesticides could be a factor in the decline of hummingbirds.
“We can't rule it out,” she stressed.
Like bees, hummingbirds return to the same place to find food and they remember where certain flowers are, noted Bishop, adding there are concerns pesticides might disrupt their memory.
But researchers don't think the decline is strictly an agricultural issue.
It could be habitat loss, or seasonal plants blooming at the wrong time of year, or even an increase in the deer population with the animals eating the same flowers the hummingbirds need for their food source, Bishop said.
The population of the Anna's hummingbird also is increasing in the area as the birds move north.
Bishop said given that bird's territorial and aggressive nature, it's possible they are forcing the rufous out.