17 Aug 2020

Surprise Little Owls

 On a return trip to a local farm to ring more broods of Swallow chicks recently we decided to check one of the regularly used Little Owl boxes. This box was installed late 2013 and wasn't used in 2014 but was first used in 2015. We'd checked it earlier in the season several times but even though a Little Owl flew out of the tree on both occasions they didn't appear to have nested. The tree has a natural cavity which is open both sides so isn't predator proof and they weren't using that either. 

The landowner photographed fledged young Little Owls around 400 m away standing outside a rabbit burrow beneath a solitary oak in the middle of a field of oats in May so we assumed this was the nest box pair relocating.

Recently a Little Owl was seen flying into the nest box so we decided to check again to see if there was a late breeding attempt. At the very least we may  be able to catch the bird in the box and check to see if it was ringed as this would provide valuable re-trap data. Last year we found that the adult female nesting in the box was ringed as a youngster in the same box in 2015. See here.

Amazingly we found not one but two Little Owls roosting inside the box. One was an adult female wit ha brood patch beginning to feather over and in full primary moult and the second was a recently fledged juvenile. The adult was unringed so wasn't the same bird that nested in the box last year. Both birds were duly ringed and it'll be interesting to see what happens next year. I've already made another box to go on the solitary oak.

Above: adult female Little Owl moulting it’s primaries

This raises several intriguing questions:

Are there two territories with one pair nesting in the rabbit burrow and one somewhere near the nest box that we couldn't find? 

Or,  is there only one territory and the birds decided on a different nest location.

What happened to last years adult female? 

Since the box was first used we've ringed 15 different Little Owls - 12 young and 3 adults.

Before the box was installed we ringed 1 adult and 1 youngster in the natural nest cavity - see here

The data shows they seem to miss a year between each successful breeding attempt. 

20.06.13 1 young & 1 adult ringed in natural nest cavity in same tree

25.05.15 5 young & 1 adult ringed.

26.05.17 3 young ringed.

05.06.19 3 young & 1 adult ringed. The adult was one of the chicks ringed in 2015

10.08.20 1 young & 1 adult ringed.

In total we've ringed 13 juv and 4 adult females, either in the box or the natural cavity in the same tree, since 2013. Each time they've nested its a different female. is the male the same bird or has there been a turnover here as well?

11 Aug 2020


 Greenfinches seem to be making a bit of a resurgence recently. Checking with other ringers it looks like the same is happening throughout the country with higher than usual recent numbers being caught. Greenfinch populations were hit hard by the pulmonary disease trichomonosis. See here.

During July and the early part of August I've ringed more Greenfinches than Goldfinches (usually the most common finch species in my garden). The majority have been juveniles but  a few adults in wing moult as well.

Greenfinches can be sexed as soon as they fledge by the amount of yellow in the primaries and tail. Male birds have yellow on the outer webs of the outer primaries that extends to the feather shaft whilst in females the yellow doesn't reach the shaft.

Below: Male Greenfinch. Euring code 3. A bird born this year and in its first calendar year.

Below: Female Greenfinch. Euring code 3. A bird born this year and in its first calendar year.

Compare the extent of the yellow in the outer primaries.

The photo's below illustrate the differences in the outer tail feathers with the male having more yellow.

The female is a second calendar (Euring 5)year bird and has replaced the right side of its tail probably due to accidental loss. The male is a first calendar year bird (Euring 3).

Finally, the adult birds have all started their post breeding moult. This second calendar year male (Euring 5) is growing P1. Notice P9 is broken whilst P10 (the outermost and smallest primary) isn't visible in this photo. It'll moult all its primaries sequentially from the inside to outside whilst its secondaries will be moulted from the outer one to inner one (closest to body). It’s nice to see Greenfinches doing well after so many years of decline.

5 Aug 2020

Scruffy corvids

Adult birds aren't looking their best this time of year. After a hectic breeding season most are starting their annual post breeding moult. I've been ringing a fair number of corvids in the garden recently and they are probably among the scruffiest birds imaginable.

Ive ringed good number s of Jays and the majority have been moulting adults. They look like they've been attacked by feather mites but it's just a natural part of their annual moult cycle.
Above:adult Jay undergoing primary moult. The old primaries (last years) are faded and brown. P7 (numbered from the inside) is still growing.
Above: same bird as open wing photo above. Undergoing body moult as well.

Above: Another scruffy individual. Its wing moult isn't so far advanced as the previous bird and it has 5 old primaries still to replace.

Above: adult Magpie undergoing primary moult and just starting body moult. This bird was aged as Euring 6 based on the amount of white in the smallest primary (P10). Juveniles and 2nd calendar year birds have more extensive black tips.

Not the prettiest birds but instructive and interesting.