Juvenile Snail Kites in Trouble

snailkite_landing1

Check out this site’s Recent Publication Page for reports published since 2000. Please let me know what is missing. For instance, I just found new research on the effects of Pomacea insularum on the Snail Kites in Florida:

 

For his Master’s Thesis at UF (see Recent Publication page), Christopher Cattau recently found that the exotic snails (Pomacea insularum) that have invaded Lake Tohopekaliga were 69% larger than the native apple snails (P. paludosa). The larger exotic snails require longer handling times for Snail Kites (Rostrhamus sociabilis plumbeus), an endangered raptor in the U.S. that exhibits an extreme form of dietary specialization. The larger size of the prey leads to increased drop rates and depressed capture rates. However, the average exotic snail weighed 3.5 times the native and provided 2.7 times energy than the average native snail. Consequently, the effects of the exotic snail on foraging behavior do not have negative energetic repercussions for adult kites. In fact, he found that adult kites are attracted to Lake Toho and that the relative contribution of the lake to the range-wide nesting effort increased from 6% to 33% after the invasion of the exotic snail.

 

The invasion of exotic snails is a problem for juvenile Snail Kites, however. The exotics were 4 times harder to capture, plus drop rates and handling times for the exotic snails were over 5 times those of the native. These effects on juvenile foraging behavior lead to insufficient daily energy balances and suppress juvenile survival.  Given the critically endangered status of the snail kite and the propensity of the exotic apple snail to spread, serious management and conservation initiatives that address the exotic apple snail are necessary to prevent further deleterious consequences for the kite population in Florida.

Posted by Jess Van Dyke

For more of Jim Neiger’s incredible images of Snail Kites on Lake Toho:

www.naturescapes.net/052006/jn0506.htm

 

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2 Responses to “Juvenile Snail Kites in Trouble”


  1. 1 Mike McMillian August 31, 2010 at 7:43 pm

    We are removing Channalized snails from a lake in Avon Park, Florida beginning tomorrow. We took some density measurements a few weeks earlier. When we remove the snails is there any point in measuring the snails? We thought it might be nice to know the percentage of adults versus juveniles. If anyone has an answer please provide it soon as we head out at 0900 tomorrow. Thank you.

  2. 2 snailbusters1 August 31, 2010 at 10:39 pm

    Well, Mike, I suppose it is a matter of cost versus benefit. Measuring each snail will consume much time and effort. Is your team’s goal to write a scientific publication on the growth rate of the exotic snails, or is it more important to actually control them? One hybrid option is to collect all the snails possible, weigh them, and then measure a few subsamples. Good luck in your work tomorrow! Jess
    P.S. Our traps might save you some time also.


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