Date: 11/11/17 5:03 am From: Dom <dom...> Subject: Re: [JERSEYBI] Corn Crake questions
Corncrakes are suffering huge declines in most of western EU. I have yet to find one in my home country despite them breeding here. I also suspect as afro-palearctic migrants they would probably exhibit higher nearctic vagrancy if the population was stable. Historic US records suggest this too.
A bit more info below from Paul at AMNH who processed this particularly individual, for those interested:
"Several people have asked about cause of death. The bird was clearly hit by a car with a fractures in both hind limbs and the pelvis.
Jonas Lai has skinned the bird and we have obtained the following data.
The bird was a male with testes 5 x 2.5 mm
It weighed 110g which is rather light for this species. Published weights range from 135-210 g ((Handbook of the Birds of Europe the Middle East and North Africa). There was no fat but the pectoral muscles did not appear atrophied.
Stomach contained tiny insect parts which have been persevered but not identified.
A moderate parasite load of Acanthocephalans was identified by AMNH parasitologists Mark Siddall and Michael Tessler"
On 11 November 2017 at 12:11, Fred Vir <avtrader...> wrote:
> Several questions/comments were received about the crake. > > I was also thinking about two of the questions. > > "When did the bird die?" > > It seemed to have died at least several hours before before we found the > bird. Rigor seemed to have already been passed when the bird was found. The > birds plumage and eyes were looking old and matted. And many birders were > there for awhile before sunrise on the subject day and should have seen the > collision. > > "As someone who's been watching birds and clearly studying them at > length...... do you believe that this bird was indeed a European vagrant, > and not an escape from a domestic game farm? " The question went on with > good points arguing that this crake was not as timid as the literature and > observers say. > > I don't think this species has been domesticated. Regardless I have seen > scores of wintering crakes/rails of various species in 4 continents and > even nocturnal species make diurnal appearances (Corn Crakes are diurnal). > Diurnal crake spp in SA and Africa can be seen almost daily, at will, in > many areas especially in winter as they dart in and out of cover. > > Some Corn Crakes have recently been observed entering houses via open > windows to feed and feeding out of farm pet bowls. > > This was an underweight individual; certainly hormonal signals that > synchronize migratory phenology cause animals to feed aggressively when > reserves are physiologically detected as being low. The bird was ~ 20 to > 50% underweight. In animals an urgent, innate need for food will often > incrementally result in reduced wariness. Remember this bird saw the ocean > and may have innately been forced to make a stand to feed at that location > or go N----terrestrial predators and cars be damned. > > Observers of this crake, including me noted that it was both wary of quick > movements by people and larger vehicles. Additionally with prior points the > strip of bluestem grass may have had more accessible insects that the > shrubs; the bird was demonstrating optimal feeding strategies. > > Also this bird showed up right on time for a putative, natural vagrant. > > Just when you are about to agree that the bird showed reduced wariness for > the above reasons I can slightly switch to your side but disagree with > causality (domestication caused the change in behavior rather than rapid > microevolution). > > Going out of the box-------there may have been a recent, rapid change in > the genome of this species that makes it slightly less wary. Its > pre-agricultural/mechanized agricultural behavior was to move deeper into > fields when danger/noise was detected. Its wariness was a partial cause of > its industrial age decline. Circling combines starting at the perimeter of > a field would mass the birds in an ever smaller central, circle of grass. > This led to great mortality via poised shooters or the combines....except > for which birds?----- The birds that flushed into more open areas out of > the high grass. > > If you are right about it being a bit less wary than old literature > .....could we be observing microevolution? > > tks > > Fred Virrazzi > Sec NJ > > > How to report NJ bird sightings: see <www.njbrc.com/index.php/repor > ting-rare-birds/> > or e-mail to <njbrcreport...> > List help: <jerseybi-request...> > List archives: https://lists.princeton.edu/cgi-bin/wa?A0=jerseybi >