A Cowbird, Starling, Goose, and Mallard walk into a rave…

and promptly left because the lasers were annoying. Well, not really according to a 2002 article. Bird damages to aircraft have left to abundant studies to determine effective means for deterring birds from airstrips and heavily utilized flyzones. Various methods have been attempted (auditory, visual, chemical, etc.), but a study actually looked to determined the effectiveness of lasers as a bird deterrent.

Using a 10-mW, continuous-wave, 633-nm laser, Blackwell et. al (2002) tested aversion of commonly plane-crashing birds to perches where the lasers were pointed or targeted at the birds directly. Neither European Starlings nor Brown-headed Cowbirds were deterred by laser treatment. Rock Pigeons (some of the least intelligent of all birds) only avoided laser targeting for the first five minutes of an 8-minute trial before the finally wised up. As for the waterfowl, Canada Geese were effectively dispersed from patches treated by the lasers during the 20-minute period, unlike the brave and magnificent Mallard who grew accustomed to the lasers after 20 minutes.

The obvious conclusion from this article is that birds are more amazing than lasers, and we should be prepared to become much more inventive when trying to fly our laughable steel imitations in their space. This article reminded me of one of my favorite XKCD comics.

Mercury & Migration

This is an old post that I could get to work because my blogger account was acting funny.

I just started working in the lab at William & Mary last Friday, and I've been trying to read lots of papers to come up with research ideas. I just read a great literature review that's still in-press and it's given me a few interesting ideas. Mercury is a toxin which readily influences bird physiology causing neurological and reproductive impairment in addition to many other detrimental effects. I'm interested in how mercury affects birds at the population level. For migratory passerines, migration can be a great source of mortality, and Saracco and Desante (2008) named 1^st year survival to be the major contributing factor for maintaining bird population levels. Undoubtedly, this is most readily influenced by habitat destruction and fragmentation, but ecotoxins could have an effect.

Mercury's physiological effects could impair the ability to successfully migrate. Mercury reduces haem production, an essential cofactor for the production of hemoglobin. Mercury also increases asymmetry, which may impair flight

 

Saracco, J. F., and D. F. DeSante. 2008. Identifying proximate causes of population trends in migratory birds: An analysis of special variation at the scale of Bird Conservation Regions in vital rates and population trends from the Monitoring Avian Productivity and Survivorship (MAPS) program. A report by the Institute for Bird Populations funded under NFWF Project No. 2005-0260-000.

Mercury Effects on Avian Embryos

The following is a brief section from my senior seminar paper on an extremely interesting and insightful article. I promise I'll get to newer articles soon, but I wanted to give this a shot and I just loved this paper.

Mercury can limit avian productivity by impairing the development of the embryo, which are especially sensitive to environmental toxins such as mercury. Heinz et al. (2008) compared embryo sensitivity of wild bird species by injecting eggs with methylmercury chloride. The response to mercury was measured using the median lethal concentration (LC₅₀), or the concentration at which the embryo mortality rate was 50%. The results show that the embryos fall largely within three sensitivity groups. At low sensitivity (LC₅₀s > 1 μg g^-1 mercury) were the Mallard, Hooded Merganser, Lesser Scaup, Canada Goose, and Laughing Gull. At medium sensitivity (LC₅₀s > 0.25 μg g^-1 mercury) were the Clapper Rail, Sandhill Crane, Ring-necked Pheasant, Common Grackle, Domestic Chicken, Tree Swallow, Herring Gull, Common Tern, Royal Tern, Caspian Tern, Great Egret, Brown Pelican, and Anhinga. At high sensitivity (LC₅₀s < 0.25 μg g^-1 mercury) were the American Kestrel, Osprey, White Ibis, Snowy Egret, and Tri-colored Heron. The rank order of embryo mercury sensitivity was also found to mirror mercury levels deposited naturally by the mother (Heinz et. al., 2008).

This research provides an invaluable means to evaluate whether mercury concentration poses a threat to specific wild species and points in the direction of which species may be at most risk. I believe this may have profound implications for conservation and management of ecotoxins. It also allows for more precise targeting for species as bioindicators.

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Heinz, G. H., D. J. Hoffman, J. D. Klimstra, K. R. Stebbins, S. L. Kondrad, C. A. Erwin. 2008. Species differences in the sensitivity of avian embryos. Archives Environmental Contamination Toxicology 56: 129-138.

Kenton’s Peer-reviewed Bird Blog?!?!

I've decided to use my summer blog as an outlet to blog about peer-reviewed science. I got the idea from one of my favorite science blogs, Pharyngula by P.Z. Meyers, and I've decided that I really need to get more into the literature in preparation for grad school. From now on I will try to post summaries and interesting questions about papers I read.

 

More to come…