Manor Farm Country Park - November 2014

It was an absolutely glorious start to the day this morning, and well worth the pre-dawn start.  We had arrived on site at 6:30 with the aim of getting at least some nets up and open before first light, and achieved that goal. Chris had to leave at around 9:30 so we limited ourselves to just six nets, which in the event was ample.

Sunrise over Manor Farm Country Park

The target species was as ever House Sparrow for my RAS project, and to colour ring birds for next years breeding season, but of course anything else that happens upon a net is also ringed. The session was very successful with a total of 33 birds ringed, 21 House Sparrow (16 new and five retraps), four Goldcrest (all new), two Dunnocks (one new and one retrap), two Robin (one new and one retrap) and three Blue Tits (two new and one retrap).

In a previous post I have discussed ageing House Sparrows in the winter, and have spent considerable time looking at the bill colour of birds, particularly males. The bill colour in males is a secondary sexual characteristic, and when sexually active in the breeding season, it becomes jet black. According to various published papers it reverts back to the pale brown or horn colour of females in the winter months.  Studies have shown that the change in colour is driven by the presence of testosterone, but one study concluded that the darkening of the bill was the result of synergistic effects of gonadotropins and testosterone (Anderson, T.R. 2006: Biology of the Ubiquitous House Sparrow - from Genes to Population. Oxford University Press).

Given that we are now at the end of November, the bill colour of male birds should no longer be black, yet two of the males clearly still had black bills.

House Sparrow - Manor Farm CP. This bird was originally ringed 2nd January 2010 and is now approaching five years since its initial ringing date

House Sparrow - Manor Farm CP. This bird was first ringed on 7th March 2014 so presumably bred in 2014

By contrast the bird below was ringed as a 3J on 22nd June 2014 and therefore is a first year bird and will not yet have bred. The bill colour of this male is the typical colour of a juvenile or female, indicating that the bird has yet to become sexually active. Another thing to note about this known juvenile is the extent of fringing on the head feathers, which is considerably greater than in the two known adult males.

First year male House Sparrow - originally ringed on 22nd June 2014 as a juvenile.

The three male below were all new birds. Given that I have been ringing at the site for over 15 years there is a pretty good chance that the majority of the new birds ringed each winter are juveniles. I admit I am never going to catch every single new bird at the site, and it is often surprising how many unhinged birds I see each visit, but a fair percentage of the adult birds at the site will be ringed.

Therefore looking at the images of the three birds below, the colour of the bill and the extent of fringing on the head feathers, could these three be juveniles too? Of the three the first bird is perhaps the least likely since it does have very dark lores and mask, and fringing is not as extensive as the other two birds below, nor in fact the known juvenile above. Looking at the two adult birds, they are showing very obvious white patches above the eye and where the black mask meets the grey feathers of the forehead, which the bird below is not exhibiting. Personally, I think all these three birds are juveniles.

House Sparrow Manor Farm CP, first ringed 29th November 2014

House Sparrow Manor Farm CP, first ringed 29th November 2014

House Sparrow Manor Farm CP, first ringed 29th November 2014

Whilst ringing the other birds of note recorded were one Raven, 27 Redwing, two Fieldfare, one Little Egret, one Grey wagtail, five Pied Wagtails and two Little Owls.

RAS Ringing at Manor Farm - June 2014

For the second time this weekend I was up at 5 am, this morning though it was for bird ringing rather than twitching. The plan was to visit Manor Farm Country Park in the hope of catching some House Sparrows for my BTO RAS project. I have blogged about the project on previous occasions so won't go through it in detail again. But for those who don't know, the aim is to catch or see as many previously ringed birds between the breeding season (March to September).

Adult Male House Sparrow

To make this easier, all of the birds I catch are ringed with a BTO metal ring on the right tarsus, and a yellow coloured darvic ring, with a single letter and two numbers, on the left tarsus. I started the project in 2000 and have to date ringed over 700 birds,

The Colour Rings used for my RAS Project

It is the peak breeding season for House Sparrows at present, and I had timed this visit in the hope that the first broods had fledged. We set six nets, around the farm buildings in locations that have previously proven to be good capture sites. Our first bird was a Carrion Crow, a species that I had not trapped at the site until last year, and now have ringed four. I think this reflects the number of birds present around the farm, which has increased dramatically in recent years. The next birds were a couple of Dunnocks and then we started catching sparrows. It was now 6:30 and the farm opened to the public at 10, so we had three hours to ring. 

It was a productive session that resulted in a total of 36 birds, of which 27 were House Sparrows. The total was made up of eight re-traps and 19 new birds, of which 15 were juveniles. Both adult and juvenile sparrows have a complete moult post breeding/fledging, therefore usually all wing and tail feathers will be replaced. Typically this will commence later in the season for adult birds, since they can have two or three broods. However, juvenile birds commence moulting in mid June, these will be the first broods.

Juvenile Male House Sparrow - note the white patch behind the eye and
rufous feathers coming through, more rufous feathers were present in the wing.

Of the birds we caught, five were in primary moult. This was generally not very advanced in that only the innermost primary had been replaced and the next was growing; all of the other feathers were old. One individual was in a curious state in that it had replaced all of its primaries, primary coverts and greater coverts, and only some of its tertials and secondaries (see below). It will be interesting to see how this bird progresses its moult, so hopefully I will catch it again over the next couple of weeks.

Wing of Juvenile House Sparrow

During the session we also caught a few other species that are breeders at the site; Wren, Blackbird and a couple of Greenfinches. The female was very tatty, but the adult male was still relatively fresh which was quite surprising for this time of year.

Adult Male Greenfinch

The only other species ringed was a juvenile Robin. I always say to my trainees that when you have a bird of a known age it is worth looking at features, such as tail feather shape and size, shape and colour of tips of greater coverts, so that they are familiar with the features when they catch a contentious bird. There was certainly no doubting this Robins age.

Juvenile Robin

RAS Ringing at Manor Farm Museum, Botley

In the year 2000 I began ringing House Sparrows at Manor Farm Country Park near Botley, Hampshire. Initially the numbers of birds ringed was fairly modest but as more birds were ringed I decided to set up a BTO RAS project. I have previously written about the project on this blog, and it is one of the driving factors why I continue to ring birds at the site. Over the years, the numbers of birds I have ringed has fluctuated quite significantly, this has been due to a number of reasons. The main issue has been work commitments, which has limited the amount of time I could put into the project. But management practices at the site, and accessibility (the site is open to the public) have also played their part. 

House Sparrow with Inscribed Darvic Ring

Many years ago I began colour ringing sparrows as I thought that this would increase the recapture rate of the project. Sparrows are very clever and will remember a net site thereby making them difficult to recapture. I began using small plastic colour rings, but it soon became evident that the sparrows were removing them. I then started using overlapped rings, before ultimately settling on overlapped darvic rings with a letter and two numbers inscribed on them. 

Graph Illustrating Total Numbers of House Sparrows Ringed per Year (blue)
and Retrapped per Year (Red)

Since the year 2000 I have ringed 656 new birds and have retrapped 453. The longest lived individual recorded to date is 4 years 276 days, and the second longest is 4 years 267 days; there have only been three retraps of birds over 4 years during my study. According to BTO data the maximum recorded age is 12 years and 12 days, which was set in 1978, so an individual from this population has someway to go to get to that ripe old age. There have been several theory's about the decline of the House Sparrow including changes in farming practices (increased use of pesticides, cleaner farming, and changes in cropping regimes), loss of nesting sites and increases in predator species such as sparrowhawk. At Manor Farm these changes have not really occurred but nonetheless the population seems to be declining. I have witnessed sparrowhawks taking birds from a recently flailed hedge, so maybe that is the cause here.  

Ageing House Sparrows after their post juvenile/post breeding moult is not possible since the extent of the moult is complete for both adults and juveniles. I have not previously looked in detail at ageing birds, but there have been several suggestions by various authors in the past describing how to separate first year from second year birds. These include a less pure grey crown and broader chestnut edges in first year birds, a difference in the pattern on the upper middle secondary covert, and the colouration of the bill, specifically the yellow bill colour and fleshy lateral lobes at the base of the bill.

Two male house sparrows, note the all dark bill and paler check of
the left hand bird, but the yellow base and grey check to the right
hand bird

Over the last few weeks have started looking at the bill on some of the birds I have captured, although at this stage I cannot make any assessments as I am catching mainly new birds. However, in male birds I have noticed considerable variation in the colouration of the bill. This is illustrated above where the bird on he left has an all dark bill, and also a more defined head pattern and a whiter cheek. However the bird on the right has a paler bill with yellow at the base, a less well defined head pattern and greyer cheek. Unfortunately both birds were new birds so I could not confirm my suspicions that the bird on the left is an adult.

Adult male House Sparrow which was originally ringed on 2nd
January 2010 and retrapped on 30th November 2013 (3 years 332
days later)

One male bird that I retrapped this weekend was originally ringed on 2nd January 2010 (image above). Like the left hand bird in the previous image this bird had a mainly black bill, although not as dark as that bird, and a clearly defined head pattern. Interestingly this bird also exhibited a very well marked black face mask and dark lores. The cheeks are pale grey in colouration.

This male again had an ill-defined head pattern, pale horn
coloured bill with a yellow base

The image above illustrates another male bird, this time with an ill-defined head pattern and black mask, paler horn coloured bill with a yellow base. The cheeks on this individual are quite pale, but appeared slightly buff coloured as opposed to the dark billed birds which were greyer. I have yet to look in detail at female birds, but of the ones that I did the bill colour seemed to be fairly consistent, being dull pink in colouration with a yellow base. Over the next couple of years I will look more closely at this and maybe by the end I will be able to confidently separate adult and juvenile birds.

Female House Sparrow with dull pink bill and a yellow base.

In two sessions this weekend I caught 50 new birds and retrapped 12, of 10 species. The new species included 28 house sparrows, eight goldfinches, five blackbirds, three robins, two blue tits and single wren, great tit, nuthatch and carrion crow. Of the retraps the most notable were a long-tailed tit, that was originally trapped 2 years and 270 days previously, a blue tit that was originally ringed 2 years 269 days previously and three House Sparrows that were ringed 4 years 276 days, 3 years 332 days and 3 years 156 days previously.