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10. september 2013

SWIFTS OVER LOMAS DE ARENA

Can anyone help identifying these swifts?
In december 2009 I photographed these swifts in Lomas de Arena. The birds were all members of the same feeding group (30+) and the number of the birds makes it impossible to tell if the same birds are featured in both photographs. As I am now illustrating Bolivian swifts I wonder if it is possible to identify the birds in these pictures, so that I can use them in my quest for learning to identify these creatures. As far as I can see the birds are Chaetura. If that is true their brown, rather than grey, hue point towards either C. meridionalis, C. pelagica or  C. viridipennis. Further a couple of features exclude C. pelagica. This leaves me with two species, C. meridionalis with a pale rump and short tail and C. viridipennis with a less pale rump and longer tail.
In fig. 1 the bird with raised wings show a well defined pale rump continuing up the lower back, passing the tertials. The tail seem very short and in my opinion both features point towards 
C. meridionalis and the pale rump out rule C. pelagica. 
Fig. 3 is the middle bird on fig. 2 enlarged. This bird is rather long tailed, seemingly longer tailed than the bird in fig. 1 and this could point towards C. viridipennis. 

fig.1


fig. 2



fig. 3


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