Three of a Kind and a Little Fire Cracker - November 2014

Wednesday 5th November began with a pre-work ringing session in the grounds of the Hampshire and Isle of Wight Wildlife Trust's, Curdridge office. I am very fortunate to work in this semi-rural location, and to have one of my trainees working out of the same office as we are able to grab an hours ringing before work. This was our first session of the winter, and what a way to start, a cracking male Firecrest, on a date reserved for celebrating Guy Fawkes. This bird is surely better than any fireworks display. The remainder of the session was quiet by comparison with a total of four birds caught, the other notable being a female Nuthatch.

Male Firecrest - Curdridge, Hampshire

Fuelled by the success of the morning, I went to Manor Farm Country Park straight after work. I had planned to meet Izzy Phillips there and we were aiming to check to see whether the Little Owls were around, and if so where they were. However, as the weather was so still, and I had my ringing kit with me, we put up a couple of nets. Both Tawny and Little Owls were active, but it was a single Little Owl that appeared first in the net.

Little Owl - Manor Farm Country Park

We were pretty chuffed with our immediate success, but were stunned to return to the net and find another two birds in it. I have previously caught two birds on an evening session, but never three.

Little Owl - Manor Farm Country Park

I have spent many hours wandering around Manor Farm Country Park at night and often encounter Little Owls running around on the fields. All three birds had wet and muddy talons suggesting that they too had been out on the fields in search of food.

Little Owl Talons

On the whole I have found ageing Little Owls to be quite straight forward, particularly with those birds caught in the autumn, since they often retain downy feathers around the nape. According to Baker (1993), the moult strategy of Little Owls is a follows;

Age code 3 - "Partial post-juvenile moult, starting soon after fledging, confined to the head, body, lesser and median-coverts; July, completed by September, October (November)."

Adult - "Complete post breeding moult starting as early as (May) June - July and completed by September or early or early November. Secondaries moult from three centres, usually around s12, s5 and s1. Tail is shed almost simultaneously."

There is slight sexual size dimorphism, with females being on average slightly larger than males, but there is a fair amount of overlap and therefore it is not really reliable.

The first bird we aged as an age code 3 (juvenile, bird of this year). See the image below; 

Adults and first winters are described in Baker as being similar in appearance, but in juveniles mesoptile down is often present on the inner-most tertials. The white spots on the head are bolder and more rounded and the white tip on p10, the outermost primary extends onto the inner web.

I have to admit I found the white spots on the head of all three birds very variable, and there was some evidence of a white tip on the primaries of two of the birds. However, looking at the overall plumage of the three birds, I was confident that that they were all first winters based on the following features.

Wing of Little Owl, showing presumed moult limit

With the first bird it was evident that it had undergone its post juvenile moult. The primaries, secondaries, tertials and primary coverts are gingery brown in colour, whereas the body, head and wing coverts, greater, median and lesser are dark brown in colour. This indicates to me that the main wing feathers (primary, secondary and tertials) have not been moulted as would be expected for a juvenile bird.

Little Owl tail, with one replacement tail feather

To further confirm this assessment, this bird has replaced a single tail feather, which it has probably lost accidentally, rather than through typical moult. The colour difference in the replaced feather and retained juvenile feathers is evident, as is the difference in the broadness, shape of the tip and extent of abrasion on the tips.

Wing of Little Owl, showing presumed moult limit

The second and third birds seem to show the same moult limit, albeit not as obviously as the first bird. In the image below it is again possible to see a contrast in the replaced adult type covert feathers and the gingery coloured primaries, primary coverts, secondaries and tertials.

Wing of Little Owl, showing presumed moult limit

For comparison below are a couple of images of an adult bird that I caught a couple of years ago, at a similar time of year. The lack of contrast between the main wing feathers and coverts is evident, as is the shape, pattern and broadness of p10. Another obvious feature is the size of the white spot, and general shape and pattern on the primary coverts in this adult bird, compared with the lack of it, or smaller size on all three of the juvenile birds.

Adult Little Owl - Note colour of wing feathers and lack of contrast and moult limit

Adult Little Owl - Note shape and pattern of p10 (outermost primary feather