Thursday, 20 October 2011

Little Owls at Manor Farm, October 2011

With the rapidly shortening days and the subsequent dark evenings, I have decided not to become an inactive couch potato, and am going to spend the dark evenings in search of birds.......and whatever else might be on offer!! On Saturday 15th October we ventured out in search of waders, but unfortunately due to people letting fireworks off over the mudflats all of the waders present were flushed so we resorted to catching a ringing an adult Mute Swan.

Not deterred by our unsuccessful attempt at waders, we headed down to Manor Farm in search of Little Owls. There are few pairs around the farm so we thought we would get there early, before they emerged from there daytime roost.....and we was not to be disappointed. We decided to put up five nets in areas where we have watched Little Owls before, and as we put up the last net...there was a Little Owl watching us.

Adult Little Owl - Manor Farm October 2011

The bird sat there for a while before flying off over the adjacent building, around the back of it and straight into one of our nets.....instant success!!! In the UK the subspecies which occurs is Athene noctua vidalii, it has generally grey-brown upperparts and heavy longitudinal stripes on the underparts.

Adult Little Owl - Manor Farm October 2011

According to Baker (1993), juvenile birds can be aged by the presence of a white tip on the inner web of primary 10, and bold white spots on the crown. Well, we found the crown spot feature slightly subjective, but the lack of white on the inner web of primary 10 clearly aged this bird as an adult.

Primaries Showing Lack of with Spot on Inner Web of Primary 10

Ageing was confirmed by the fact that this bird was in wing moult. Again according to Baker, adults undergo a complete moult post breeding which starts as early as May and is completed by September through to early November. 

Wing of Little Owl showing Moult Limit in Secondaries - October 2011

Juvenile birds however undergo a partial post juvenile moult, which commences just after fledging and is confined to the head, body, lesser and medium coverts.

Wing of Second Little Owl - October 2011

We could hear a couple of Little Owls calling elsewhere on the site but it was not until we went to take our nets down that we caught our second. This bird was also an adult, since it lacked the white spot on the inner web of primary 10 and was again in primary moult.

Little Owl, Manor Farm - October 2011

Again, according to Baker it is possible to sex individuals on wing length, with adult males averaging 163mm, with a range of 158-169mm and adult females averaging 166mm, with a range of 161-173. Both our birds were probably females with wing lengths of 171 and 169, the latter bird appeared to have an old brood patch.

No comments:

Post a Comment

Related Posts Plugin for WordPress, Blogger...