Tag: Birds

A common pesticide delays migration and causes significant weight loss in white crowned sparrows.

On By Mike and Christy6 Comments

Neonicotinoids are the most commonly used class of pesticides in the world protecting crops from insects but not without untoward side effects including killing beneficial insects that pollinate the crops we need. Additionally this class of pesticides has been show to have negative effects on songbirds in laboratory studies.1 Migrating songbirds frequently forage and ingest seeds treated with these pesticides during their migrations. Until now the effects of neonicotinoids on free living wild birds had not been studied.

As reported by Kristine Liao in Audubon:

“A new study published online today in Science provides the first evidence that neonics harm songbird populations in the wild. University of Saskatchewan researchers found that White-crowned Sparrows that consumed small doses of a neonic called imidacloprid suffered rapid weight loss and delayed migration, both of which can hinder birds’ survival and ability to reproduce.”2

This is an interesting study where researches captured free-living White Crowned Sparrow and feed them them either a low dose, high dose pesticide or a control meal as well as fitting them with a tiny radio transmitter that allowed  the freed birds to be tracked over a 100,000 square-kilometer area.

The sparrows fed the highest dose lost on average 6% of their body weight and 17% of their fat reserves both of which are vital for fueling successful migrations.3 Sparrows who consumed the pesticide then delayed their migration between 2-4 days compared to the control fed birds.

As for the potential consequences of songbirds delaying their migration in response to pesticide intake, one of the studies authors, Bridget Stuchbury,was quoted in a report by Smithsonian as saying:

“that extended rest stops can leave birds—already disoriented by the toxic chemical—vulnerable to predators. At the same time, she explains, late arrival to a final migration destination may reduce a bird’s chances of finding a mate, particularly if it has a shorter breeding season.”

Neonicotinoids are considered cheap insurance against insect-pests for many crops including corn, canola and soybeans and one of the most widely-applied pesticides in the world. The scientific evidence is now clear that these pesticides have harmful effects on bees, fish and now bird populations. How much more evidence will be required before we stop using these chemical willy-nilly… Before, or after,  we loose innumerable bees, birds and fish?

References:
1. https://www.sciencemag.org/news/2019/09/common-pesticide-makes-migrating-birds-anorexic

2. https://www.audubon.org/news/a-widespread-pesticide-causes-weight-loss-and-delayed-migration-songbirds

3. A neonicotinoid insecticide reduces fueling and delays migration in songbirds. Margaret L. Eng, Bridget J. M. Stutchbury,  Christy A. Morrissey, Science  13 Sep 2019:Vol. 365, Issue 6458, pp. 1177-1180.  DOI: 10.1126/science.aaw9419

Scruffy

On By Mike and Christy2 Comments

Coopers_hawk_bw_1

On Saturday at mid-morning we spotted this Coopers hawk tidying up a bit on a broken old Cottonwood branch. He looked like he has had a bit of a rough time lately with his feathers looking downright scruffy. After a half hour or so of preening his feathers were back in fine order and he was off again hunting in nearby woods.

Song birds are shrinking

On By Mike and Christy24 Comments

Bergmann’s rule posits that populations and species of larger sizes are found in colder regions while in warmer regions species are smaller.

A study published yesterday in the Journal Ecology Letters reports that over the pervious four decades there has been, on average, a 2.4 percent decrease in the size of the length of the tarsus bone, a standard marker for bird size,  in a sample population of over 70,000 birds from 52 species. The changes in tarsus length were correlated with the increase temperature. The lead authors of the study suggested two explanations for the decrease in body size.

“The first is developmental plasticity, in which individuals that mature in warmer temperatures tend to develop into smaller adults,” Weeks explained. “The second is natural selection, in which smaller birds tend to do better — in survival, reproduction, or both — in warmer temperatures, leading to a shift in the average size of individuals in a population.”

In addition, the study found consistent increases in the wing length of 1.3 percent in 40 of the species. The reason for in increase in wing length is unclear  but the authors hypothesized that increasing wing length may represent a compensatory adaptation to maintain migration as reductions in body size have increased the metabolic cost of flight. Like many of the consequences of climate change, the changes measured in bird size, are not perceptible to the naked eye.

There is a good summary of the study here by the Audubon society.

Click any image for slide show.

 

Western Grebe

On By Mike and Christy21 Comments

Western_grebbe_1

We usually do not see Grebes on the local pond during winter in our neck of the woods. However, last week, this Western Grebe was swimming in a small section of a local pond that remained unfrozen. Perhaps she if off course in migration and landed here to rest and refuel. Although it was a pleasure to see her, I hope she takes advantage of this weeks thaw to get back on track and is gone the next time I visit this pond.