I doubt that apparent size would be much help with these Robin. HANZAB notes the difficulty of ageing, but says the juveniles have more subdued dark markings and a more conspicuous orbital ring. Below is an apparent adult from that site, first picked up on Jack Holland’s ‘nest workshop’ in November 2010. Below that are 2 apparent juveniles photographed on the date given. Those 2, and your 4, do appear to be young birds on the basis of the HANZAB criteria, when compared with the first bird below, particularly the muted head markings.
From: Robin Eckermann [
Sent: Saturday, 31 December 2011 2:03 PM
To:
Subject: [canberrabirds] Re: Youngsters ... probably!
Further to my posting yesterday, I had some off-chatline dialogue with Philip Veerman about the picture of two (possibly young) owlet nightjars. That prompted me to go back and check on an earlier picture of a pair in the same hollow, taken in early February this year (assuming you get this before New Year!) I thought folk might be interested in the comparison ...
When you compare the LHS picture (taken yesterday) with the older RHS picture, it looks like the birds I saw yesterday were quite a bit smaller - perhaps reinforcing the hypothesis that they were quite young birds. The pictures are taken from a different angle, so that's why the profile of the wood doesn't match exactly.
Regards ... Robin
