Saw this on the CCB Blog, and didnt see any mention of it here. It's very interesting and answers some questions regarding the 2 eagles found dead:Statement prepared by Dr Bryan Watts, Director of The Center for Conservation Biology, with respect to the death of an adult and a juvenile bald eagle at Norfolk Botanical Garden.
Eagle Mortality Norfolk
Botanical Garden
On a global scale, our electrical infrastructure kills millions of birds annually. There are three common
ways that birds are killed when interacting with transmission or distribution lines. The most common of these is referred to as pole electrocution. Birds perching on power poles are electrocuted when they come in contact with two conductors and complete a circuit. To overcome this problem, power companies have retrofitted power poles in areas known to have problems to prevent birds from making these contacts. The second most common cause is referred to as a mid-line electrocution which occurs when a large bird flies through the lines and is able to complete a circuit by touching two wires with its wingtips. The third form of mortality is when a bird flies into lines does not complete a circuit but is killed by the trauma. Bald eagles are particularly vulnerable to mortalities related to the electrical infrastructure because they are large enough to bridge the gap between conductors.
In a recent investigation of 62 eagle mortalities caused by power lines within the upper Chesapeake Bay, Bryan Watts and Libby Mojica from The Center for Conservation Biology determined that both line location and context had a significant influence on the likelihood that they would kill eagles. Lines that are near water or foraging areas are crossed regularly and have a greater likelihood of being problem lines. Lines that are exposed in open areas are much more likely to kill eagles compared to those that are associated with screening vegetation. This is because tall trees planted near electrical lines serve to shift the flight line of eagles above the power lines.
In just the past 2 weeks, two eagles have been found dead within the grounds of Norfolk Botanical Garden that were associated with power lines. The first was an adult-plumaged female and the second was a juvenile-plumaged bird. The juvenile clearly died by trauma-related mid-line strike, and the adult is suspected as having also died by trauma-related mid-line strike. The extent to which these mortalities were facilitated by interactions with other eagles is not clear. We have very little information on causes and rates of eagle mortality but such events are likely much more common than we currently know.
Link to CCB site:
http://eaglenest.blogs.wm.edu/2012/01/1 ... al-garden/
Login
Register
FAQ
