Piping Plover: head scratching - case of leg movement disorder

Banded Piping Plover – leg movement disorder Let me point out something at the beginning - I am absolutely not suggesting that this disorder is/was caused by bands/flags placed on the leg. In fact as you will see I found no reason to support that but because welfare, especially of birds with so small breeding population, require taking every possible cause under consideration I will leave this possibility to open discussion. A quick summary of important facts: an average life span of Piping Plover is below 5 years. Maximum observed longevity is 14 years – two females in wild. Observed female was 7 (~6y 10m) years old (8 cy) in 2015 and 8 (~7y 10m) years old (9 cy) in 2016. Already surviving and beating the odds against her but far from being very old in piper’s standard. Piping plovers are using indirect method to scratch their heads; BTW not many species are known to use both methods (direct and indirect). No need here to describe these methods; there are illustrated shortly (~ 1 min) in the video (total ~4 min) anyway. These are only two methods used by birds to scratch their heads using a leg. Third method to scratch the head, “perch-scratching”, does not involve the leg. Also there is a third year in row I observed this female showing up in about the same time during spring migration; have no observation of head scratching during the first year. I am not going to describe details as those are shown in the video that includes many detailed captions. In short: Last year I found one Piping Plover female during spring migration that kept trying to scratch her head directly – as you will see unsuccessfully. A few days later I re-found that bird and she continued to try (very often) with the same negative results. She was showing signs of fatigue but (same as a few days before) have no problem with wings or legs in general. Perfectly able to walk, run, stretching wings, taking off and fly normally. I did not find her that spring (2015) in following days. Year later (a few days ago) she showed up here again (seems that this is her stopover spot during spring migrations) having exactly the same problem with left leg movements when trying to scratch her head. BTW I never saw her trying to scratch her head using right leg so I do not know if she also have problem with the other leg or not. She was very active during that evening and was foraging most of the time showing no problems (or abnormalities) when walking, running or foot trembling when foraging. Again, a short (~4 minutes) video (but I tried to pack it with all important behaviors and descriptions) should adequately illustrate the disorder – much better than my written notes here. I am very interested to hear all opinions on this subject including information about similar cases (if any) observed by others (and about cases of similar disorders in other birds as well). Although some authors suggest that the head scratching in birds is essential I do not see it as critical. I have no doubt that it is a very important comfort behavior but as we can see in described case this Piping Plover did survive (for at least a year)and shows no sign of problem with keeping plumage in good condition nor has noticeable problems with foraging, walking, running or flying. I have seen many gulls that lost one foot and did not show any problem to keep head feathers in good condition. They often trying to reach head with the stump and perform up and down leg moment without touching the head. BTW below are links to photos showing a Piping Plover and Least Tern that lost one foot. Judging from the stump condition it might happened quite long ago. Both birds appeared to be in very good condition (LETE in beautiful breeding plumage, one of first this season with only one, P10, black primary and new P9 fully grown). How PIPL kept the bands on the stump is beyond my imagination. I was not able to find a bander and confirm the identity of this individual; perhaps this bird lost band(s) on the other leg (even more strange). Piping Plover with missing part of the left foot http://www.pbase.com/mbb/image/163059305 http://www.pbase.com/mbb/image/163072487 Least Tern with one foot missing attempt to scratch its head http://www.pbase.com/mbb/image/163072482