With all the talk about bluebirds you may wonder why I find this Gannet post from another list germane. I ported it over just because there is a lot of good general information in here about bird mortality and about a very level-headed way to discuss it. And by the way, I think the bluebird discussion here has been very level-headed and informative. I've learned a lot on a subject I know very little about. Greg Hanisek Waterbury ----- Original Message ----- From: "Mike Patterson" <celata@PACIFIER.COM> To: <BIRDWG01@LISTSERV.ARIZONA.EDU> Sent: Thursday, May 17, 2007 11:13 AM Subject: Re: [BIRDWG01] Gannet die-off in south east Florida > The why of die-off is always vexing. > > One of the most important things to remember, especially in seabirds, > where access to live individuals is limited, is that the sample is > biased. The only birds being analysed are the dead and dying birds > that wash up, the sick ones. You have no information on the birds that > are alive out on the ocean. They may all be perfectly fine or they > may be just not quite as sick. You can't necessarily extrapolated > health of the population based on the dead birds on the beach. > > We routinely see higher carcass deposition in years when breeding > was very successful. More juveniles coming off the nests translates > to more (mostly juvenile/immature) birds dead on the beach. The > attrition rate among most bird species is something over 80% in the > first year even under the best of conditions. > > During the big Northern Fulmar die-off, we could never be sure > whether there were actually more birds dying than usual or that > they were dying closer to shore and consequently more were making > it to the beach rather than sinking to the depths of the ocean. > > Of course then one has to ask... why were they spending time closer > to shore? > > My advice: don't say anything that isn't something you know from the > data. > > "The birds we are finding on the beach appear to mostly be juveniles" > > "The birds we are finding on the beach apear to have starved... > were oil-soaked.... > were wearing gulls-gone-wild t-shirts..." > > "We have no information on healthy live birds out in the ocean." > > "Die-offs occur annually, this is/isn't larger than average." > > "There are many possible reasons for this die-off, attributing this > to any single cause would be premature at this time." > > Speculation will all too often be printed as fact by the media. > Try to avoid having your quote on dead gannets be the one that gets > put in boldface in the article on the die-off. > The media will continue to sniff around 'til they find someone > willing to pin this on el Niño and Global Warming (which may or may > not be factors), depletion of fish stocks (which may or may not be > a factor), plastic or other polution sources (which may or may not > be factors) or the Bermuda Triangle (I was watching this thing of > the Discovery Channel the other night...) > > -- > Mike Patterson > Astoria, OR > celata@pacifier.com > > Lies, damned lies and White-throated Sparrows > http://tinyurl.com/34vgwm > > > Join or Leave BIRDWG01: > http://listserv.arizona.edu/cgi-bin/wa?SUBED1=birdwg01 > > Archives: http://listserv.arizona.edu/archives/birdwg01.html > >