Tracking study shows Northern Gannets favor Gulf of Mexico more than expected

15 03 2012

Immature Northern Gannet: young birds were hit hard by the BP spill. (Photo credit, Andreas Trepte)

A brief article just out in Biological Letters indicates that Northern Gannets visit and overwinter in the Gulf of Mexico more than previous banding studies had indicated. The article describes the use of GPS locator tags to track the movements of gannets from their breeding grounds in Canada. The researchers demonstrated that about 25% of the North American gannet population utilizes the Gulf at some point. The impetus for this study was largely the BP Deepwater Horizon spill, in which Northern Gannets were number one in terms of percentages of bird species found oiled after the disaster. But the population level impacts of the spill were difficult to extrapolate without a clear sense of how many gannets were likely in the area at the time. In April, when the spill began, most adult gannets would have headed north to the breeding grounds. But approximately 50,000 immature birds, ranging in age from one to five years old, have no reason to hurry away from the Gulf’s waters. It’s this younger age group that was likely most severely impacted by the spill. As a result, it’s difficult to predict the long-term population effects on this species. Juveniles have a high mortality rate anyway, and, in terms of breeding, are less valuable to the population than established, experienced breeders who can produce new chicks for more than a decade. The authors of the study suggest that future years may show a subtle, lag decline in the numbers of gannets, reflecting the hit they took during the spill year, or there may, in fact, be no perceptible effect on the population. This is good news for the gannets, but this study also drives home the need for these more expensive tracking studies to supplement cheaper, but larger scale, banding efforts. In fact, estimates of the number of gannets using the Gulf based on the geo-locator data are more than twice the estimates based on band data. This means that estimates of spill-related mortality would be similarly skewed if scientists rely solely on band recoveries. The two types of studies can be complementary, and events like the BP spill demonstrate the need for continued monitoring of the marine birds, even ones as seemingly “safe” as the ubiquitous gannet. It’s when we look away that everything seems to fall apart.



2 responses

26 03 2012
jerry and Diane Hequembourg

Missed the talk but read the article. And we continue to do out walks, just a few miles South of the infamous Wellfleet Bay!

19 06 2012

By reading your article i came to know many things about Northern Gannets and the use of GPS locator.
I like it 🙂
I also read another article based on this GPS tracking in B-tracking
For more news about this GPS visit GPS



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