Here's another example of an Peregrine with crossed mandible...
Shot in winter of 2012, Dec @ Charakla Salt pans, Gujarat
On Sun, Jun 16, 2013 at 11:00 PM, Hans Peeters <hjpeeters1@gmail.com> wrote:
Notice that the prinias in both photos are no longer able to preen their tails properly. This species may not particularly suffer from a tail with reduced function, but other species may not be that lucky. Other important feathers may suffer as well, and of course there is the problem of feeding. It's possible that certain pesticides are to blame. Organochlorines, like PCBs, are hormone mimics (both, for example, have been implicated in the development of secondary sex characteristics of the opposite sex in organisms with residues); however, I don't know how that would affect beak development -- obviously in most birds, bills don't represent secondary sex characteristics.
For a good and depressing assortment of deformed beaks, google "beak deformities in birds" and click on images.Cheers,
Hans--On Sat, Jun 15, 2013 at 1:32 PM, Arka Sarkar <sarkar.arka@gmail.com> wrote:
Here is a record shot of another Yellow-bellied Prinia from the same place and day. In this case, both the upper and lower beaks are deformed.
--Cheers,Arka SOn Sat, Jun 15, 2013 at 11:19 PM, Arka Sarkar <sarkar.arka@gmail.com> wrote:The marshes of Joka in the southern outskirts of Kolkata are a breeding ground for good number of Yellow-bellied Prinias. I have been observing those for the last few years. This year, I noticed a number of individuals with beak deformities, something that I had not noticed before. There are both types of deformities - ones where the both the maxilla and the mandible are overgrown and crossed, and ones, like the attached where only the maxilla is overgrown. I have noticed this in crows in the same area, but not in other birds. These marshes are adjacent to agricultural fields where pesticide use is heavy. I wonder whether that has to do with anything.But the extent of deformation here is minor compared to the ones that Hans mentions. These prinias seemed to be doing well - at least for now.17th March,Joka Marshes. Southern outskirts of Kolkata, India.
--Cheers,Arka SOn Sat, Jun 15, 2013 at 7:07 AM, Hans Peeters <hjpeeters1@gmail.com> wrote:Hi Rajneesh,Yes, there has been an increase in beak deformities, spectacularly so in Alaskan chickadees. Many other bird species are affected, and there is a suspicion that at least in some of the cases (such as those of the chickadees), there may be a connection to polychlorinated biphenyls (PCBs). Because there are a great many of the affected birds in the Pacific Northwest of the United States, some people think that the pollutants may have originated in east Asia (i.e., Japan and/or China). PCBs, as you probably know, are used for a great variety of industrial purposes, such as electrical insulators, capacitors, etc., even road sealants to keep down the dust. Their use was outlawed in the U. S. in 1979 for health reasons.
There are at least two kinds of beak deformities. The type seen in chickadees and many other birds (including raptors) involves overgrowth of both the upper and lower beak, sometimes bizarrely so. I've seen photos of a nuthatch with a beak at least half as long as its body. In such cases, the maxilla and mandible frequently cross and severely affect feeding.
The type seen in your photographs (and they're excellent illustrations!) chiefly involves the maxilla. This kind of malformation is often seen in captive raptors chiefly because of the nature of their diet (frequently day-old chicks or bone-free meat). Normally, a wild raptor's beak is worn down by the bird pulling on bones and tendons and by later vigorously rubbing its bill on a hard, rough substrate, such as a rock or on sand, to clean it and coincidentally perhaps to sharpen it. I would suspect that a steady diet of spiny-tailed lizards for a laggar would not promote beak wear, nor would fish as an only food do so for the kite.
Best regards,Hans--
On Thu, Jun 13, 2013 at 7:22 PM, Rajneesh Suvarna <rajneeshsuvarna@gmail.com> wrote:
Hi Hans,The number of raptors that I have seen with deformities seems to have gone up in the recent years, especially in the ones closer to human habitation (the last part could be because I would get to see those more frequently) and have included kites (Black, Brahminy & Black-shouldered), White-eyed Buzzard, Steppe Eagles.. The incidence seems to be high in the "wanna-be" raptors, the crows.Is the incidence of deformities really going up? Is it due to change of diet, more dependence on waste generated by humans or their prey base being high on 'supplements'.On Fri, Jun 14, 2013 at 4:26 AM, Hans Peeters <hjpeeters1@gmail.com> wrote:
Nice photo, Rajneesh, but do take note of the severely overgrown beak. A potentially fatal flaw, because unless that overlong tip breaks off, it will eventually interfere with eating.
Best,Hans--On Thu, Jun 13, 2013 at 10:49 AM, Rajneesh Suvarna <rajneeshsuvarna@gmail.com> wrote:
A Laggar Falcon (Falco jugger)Tal Chapper, 24th Jan--
You received this message because you are subscribed to the Google Groups "delhibirdpix" group.
To unsubscribe from this group and stop receiving emails from it, send an email to delhibirdpix+unsubscribe@googlegroups.com.
To post to this group, send email to delhibirdpix@googlegroups.com.
Visit this group at http://groups.google.com/group/delhibirdpix.
For more options, visit https://groups.google.com/groups/opt_out.
Hans Peeters
1050 Kilkare Road
Sunol, CA 94586
USA
925-862-2102
http://peeters.homestead.com
http://www.ucpress.edu/books/pages/10558.php
http://www.ucpress.edu/books/pages/9944.php
--
Hans Peeters
1050 Kilkare Road
Sunol, CA 94586
USA
925-862-2102
http://peeters.homestead.com
http://www.ucpress.edu/books/pages/10558.php
http://www.ucpress.edu/books/pages/9944.php
You received this message because you are subscribed to the Google Groups "OrientalBirdingPix" group.
To unsubscribe from this group and stop receiving emails from it, send an email to orientalbirdingpix+unsubscribe@googlegroups.com.
To post to this group, send email to orientalbirdingpix@googlegroups.com.
Visit this group at http://groups.google.com/group/orientalbirdingpix.
For more options, visit https://groups.google.com/groups/opt_out.
--
Hans Peeters
1050 Kilkare Road
Sunol, CA 94586
USA
925-862-2102
http://peeters.homestead.com
http://www.ucpress.edu/books/pages/10558.php
http://www.ucpress.edu/books/pages/9944.php
You received this message because you are subscribed to the Google Groups "delhibirdpix" group.
To unsubscribe from this group and stop receiving emails from it, send an email to delhibirdpix+unsubscribe@googlegroups.com.
To post to this group, send email to delhibirdpix@googlegroups.com.
Visit this group at http://groups.google.com/group/delhibirdpix.
For more options, visit https://groups.google.com/groups/opt_out.
Rajesh Shah
You received this message because you are subscribed to the Google Groups "delhibirdpix" group.
To unsubscribe from this group and stop receiving emails from it, send an email to delhibirdpix+unsubscribe@googlegroups.com.
To post to this group, send email to delhibirdpix@googlegroups.com.
Visit this group at http://groups.google.com/group/delhibirdpix.
For more options, visit https://groups.google.com/groups/opt_out.
No comments:
Post a Comment