Wednesday, June 18, 2008

The Seawatch - Nature's boring miracle

A 7-year old smelly apparition crawled into the bed at 5 am, waking me up enough to get me out birding and leave it snoring with its mum. I went down to the sea, to see what I could see. Must be a bit of seabird action going on. And there was, kind-of, if you include Guillemots and Razorbills going back and forth with their fish, and feeding flocks of Black-legged Kittiwakes, with the odd Atlantic Puffin and a few Northern Fulmars.

Best bird, a single Black Guillemot heading south. Wow, they're smart. We're right at the edge of the range here, and they've been less-than-annual on my Newtonhill list.

150 Northern Gannets north, and 240 south, between 5.15 and 6.35, Common Scoters (30N 49S), Sandwich Terns (2N 3S), 1 Arctic Tern feeding with Kittiwakes offshore, 1 Red-throated Diver north, 4 Manx Shearwaters north, 1 south and 1 with the Kittiwakes,mand a single Grey Heron north. None of your Long-tailed Skua nonsense for me, ta very much.

Thanks to Louis Bevier, who pointed out this paper, regarding the use of unverified anecdotal sightings to build up false pictures of the persistence of animals in regions from which they have gone extinct. It uses three examples, the Fisher (a kind of dead-hard Pine Marten, as far as I can tell) and the Wolverine in California, and errr... the Ivory-billed Woodpecker. Very refreshing to here someone else tell it as it is.

'Although it is always possible to invent rationales to explain the lack of conclusive evidence, available evidence indicates that the ivory-billed woodpecker probably became extinct in the southeastern United States by the middle of the twentieth century.'

and this bit is for the 'there are too many sightings to dismiss them' all school:

'As a species becomes rarer, the proportion of false positives will increase. For example, in the contiguous United States, bobcats (Lynx rufus) are common and Canada lynx (Lynx canadensis) are rare; occasionally bobcat observations are misidentified as lynx. Even if such misidentifications happen only 1% of the time, for every 1000 bobcat sightings, 10 will be identified as lynx, and false lynx observations can easily outnumber actual ones. Even if lynx were extirpated from the area, lynx would continue to be reported each year and, over many years, hundreds of spurious lynx observations would accumulate.'

The emphasis is mine. Replace bobcat with PIWO, and lynx with IBWO, and you get the point. Hell, maybe you got the point already. The whole thing must be as welcome as a cup of cold vomit in some parts of the USFWS.

Ref: pdf

BioScience Volume 58, 549-555 (2008)

Using Anecdotal Occurrence Data for Rare or Elusive Species: The Illusion of Reality and a Call for Evidentiary Standards

Kevin S. McKelvey, Keith B. Aubry, and Michael K. Schwartz

Anecdotal occurrence data (unverifiable observations of organisms or their sign) and inconclusive physical data are often used to assess the current and historical ranges of rare or elusive species. However, the use of such data for species conservation can lead to large errors of omission and commission, which can influence the allocation of limited funds and the efficacy of subsequent conservation efforts. We present three examples of biological misunderstandings, all of them with significant conservation implications, that resulted from the acceptance of anecdotal observations as empirical evidence. To avoid such errors, we recommend that a priori standards constrain the acceptance of occurrence data, with more stringent standards applied to the data for rare species. Because data standards are likely to be taxon specific, professional societies should develop specific evidentiary standards to use when assessing occurrence data for their taxa of interest.


DorsetDipper said...

shoot 'em. Its the only way you can be sure.

Martin said...

That's a *lot* of Pileateds needing snuffed. Can the USFWS fund it??

Gavin Haig said...

Explains why LSW keeps getting 'seen' and 'heard' on my patch, whereas we know in reality that they have been extinct in E Devon for five or six generations...

Nice blog by the way :-)

JH said...

I heard a most-convincing double-knock on Saturday... shame it was on Ranscombe Farm in Kent (when we all know it survives in Norfolk).

John said...

Thanks for the link to the article. So that's why I never saw any Fishers or Wolverines in the Sierra Nevada. Of course I might have seen them anecdotally, I suppose. And also no Ivory-billed Woodpeckers here, except the anecdotal sort.