Tuesday, 26 April 2011

St Aldhelms Head, Dorset - 26th April 2011

Today I had the chance to go to St Aldhelms (or St Alban's, to some) Head in Dorset, with the aim of observing some visible migration or vis-mig to hard core birder's. The weather conditions were not ideal, with a stiff north-easterly breeze blowing, but today was the day I had planned to go so I stuck to the plan.

I arrived at the car park at Worth Matravers at around 05:50, and walked the track to the headland. It was freezing, but my mind was diverted away from the cold by the bird song. Whitethroats were common, but so were corn buntings and yellowhammers; the latter two are species that used to be common in Southern Hampshire, but are becoming more uncommon these days.

I settled under a sheltered cliff and scanned the sea; not much happening other than the odd northern gannet and herring gulls passing. As I continued to scan a steady stream of guillemots headed west and northern fulmers drifted back and forth. Visible migration was slow, barn swallows and house martins being the most numerous, along with occasional sand martins and a single yellow wagtail. 

But as I continued to scan, my attention was caught by a large dark shape rolling forward in the water, then another and another. Bottle-nosed dolphins - in all, at least 12 individuals were present, but there may well have been more as the group was quite widely spread, and they were never all in view at the same time. The bottle-nosed dolphin is a large and robust dolphin which is uniformly grey above with paler flanks. However, when backlit by the sun they can appear extremely dark.

Bottle-nosed Dolphin, St Aldhelms Head - April 2011

The dorsal fin is located centrally on its back, and is tall and falcate, but the most distinctive feature has to be the obviously bottle shaped nose.

Bottle-nosed Dolphin, St Aldhelms Head - April 2011

I was torn between trying to get some good photos or try to get an accurate count of the number of individuals, in the end I tried both. And I was glad I did, because as I continued to watch the group swimming east, I noticed at least three young calves.

Two Adult Bottle-nosed Dolphins and Calf (centre front),
St Aldhelm's Head - April 2011

At the end of the day I headed home content with my sightings, despite the lack of migrant birds; whales and dolphins are fascinating animals and I never tire of seeing them.

Monday, 25 April 2011

The Barley Bird has Returned - April 2011

Over the last week I have had the opportunity to carry out two ringing sessions, both at Botley Wood, and both carried out with the background accompaniment of common nightingale song. The first session was carried out on 17th April and ended with the grand total of 30 new birds and four re-traps. Two of the re-traps were great tits, that were captured on 31st May 2010. Other birds captured included two blackbirds, six blackcaps, two chiffchaffs, and a female bullfinch and a male song thrush.

The most striking bird captured was an adult Eurasian jay. It was aged by the broadness and shape of the tail feathers and the number of black bars on the outermost greater covert.

Adult Eurasian Jay, Botley Wood - April 2011 T. D. Codlin

The striking turquoise primary, alula and greater coverts, although visible in the field, are probably best appreciated when seen close up.

Open Wing of Eurasian Jay, Botley Wood - April 2011 T. D. Codlin

One of the target species for my ringing studies at Botley Wood is the marsh tit. This species is considered to be in decline, but at this site it is a species that I regularly capture. Individuals can be incredibly variable and subsequently can be difficult to separate from the closely related willow tit. Features such as the pale wing panel and glossy or matt cap, can appear regularly in both species. However, help is now at hand. A recent research paper studied both marsh and willow tits and identified two new features; the first being the contrast between the white ear coverts and brownish side to the neck, and the second being a white mark on the cutting edge of the upper mandible, near the base.......both features are clearly visible on the picture below.

Marsh Tit, Botley Wood - April 2011 T. D. Codlin

Only 22 birds were captured on the morning of the 21st April, but the numbers didn't matter as the highlight was the capture of my first two barley birds of the year. The first bird was an adult male that I first captured last year, when it was returning for its first summer. This bird was very vocal, and as well as its typical song, was emitting loads of croaking and wheeting calls. This behaviour is typical of a male which is courting a female, and sure enough, the second bird I captured was a probable female. This bird was a first summer bird with a maximum wing chord of 80mm; typically male birds have maximum wing chords of between 84 - 88mm, females are usually a couple of millimetres shorter, but as always there is some overlap.

Adult Male Common Nightingale, Botley Wood - April 2011 T. D. Codlin

The combination of the behaviour of the two birds, the soft contact calls and short wing length of the second bird are indicative of a female, but in the absence of any conclusive features, such a a brood patch, I could not be certain, so left the bird unsexed. 

Adult Male Common Nightingale, Botley Wood - April 2011 T. D. Codlin

The other species captured included more blackcaps, chiffchaffs, blackbirds, blue tits and great tits along with my first common whitethroat of the year. Common whitethroats are a regular summer visitor to the site; the captured bird was aged as a first summer due to its extremely worn wing and tail feathers and small amount of white in the outer tail feathers.

Common Whitethroat, Botley Wood - April 2011 T. D. Codlin

With ringing activities finished and all the nets down we headed back along the road towards our cars, and there in the middle of the road was an adder. Typically, it immediately coiled up and prepared to strike rather than run (well slither!).........

Adder, Botley Wood - April 2011 T. D. Codlin 

........but once it realised that we were not intimidated and only interested in taking pictures, it beat a hasty retreat back into the undergrowth.

Adder, Botley Wood - April 2011 T. D. Codlin

Friday, 15 April 2011

Manor Farm Country Park - 9th April

Things have been a little hectic of late which has meant me not having the time to update my blog, but with a couple of hours to spare today, I thought it would be the ideal time to post last weekends activities.

Bird ringing was limited to Saturday and a measly total of only 20 birds were captured, of which six were recaptures. After the previous weekends migrants, there was an immediate return to resident species, but despite this there were some cracking birds captured. The pick of them included a pair of adult chaffinch's and a stunning male greenfinch.

Adult male chaffinch Manor Farm Country Park 9th April ©T.D.Codlin

I aged both the chaffinch's by the shape and pattern of the tail feathers, in fact the tail of the male exhibited all of the features that would expected on an adult bird.

Tail of male chaffinch showing well defined pattern and obtuse tip of 5th tail
feather and black centre to central tail feathers ©T.D.Codlin

I also managed to catch a few more house sparrows and add to my totals for my RAS project. Although the retrap numbers were low, only two birds recaptured, I was able to fit another six colour rings.

Male house sparrow wearing his lovely new colour ring ©T.D.Codlin

With the warm sunny days that we have been having recently there has been a dramatic increase in insect activity, some species having emerged from hibernation, such as small tortoiseshell, red admiral, peacock and comma butterflies...

Comma butterfly recently emerged from its winter hibernation ©T.D.Codlin 

...whereas many moth species, such as frosted green and streamer, have a flight season of April - May and have emerged after spending the winter months overwintering as a pupa.

Frosted green moth 9th April 2011  ©T.D.Codlin

Streamer moth 9th April 2011  ©T.D.Codlin

The other species captured over the weekend were hebrew character, common quaker, small quaker, blosom underwing and lunar marbled brown.

Sunday, 3 April 2011

Botley Wood, Hampshire - 3rd April 2011

Today I decided to visit Botley Wood with a view to cutting in the net rides in readiness for the arrival of 'the barley bird' or common nightingale, to most of you. But alas due to the regular management of the site, all of the scrub in the vicinity of my trapping area from last year had gone! Unfortunately, one of these areas was the territory of a bird that I have been capturing for the last six years, this year would have been its seventh, and possibly would have been a national longevity record for the species.......I will keep you posted if it returns.

With no net rides to cut in I decided to put up some nets and try to catch some of the singing chiffchaffs and willow warblers that were present instead. Success was almost instantaneous, with the first bird captured being a 2nd year male chiffchaff.

Chiffchaff Botley Wood - April 2011 (T D codlin)

Adult chiffchaffs undergo a complete moult in the summer after breeding, whereas juvenile birds undergo only a partial moult. Therefore juvenile birds can often be aged in spring by the extent of wear and the colouration of their flight feathers. This bird was aged due to the extent of wear on the tips of the primaries and tail feathers, and by the presence of two generations of feathers within the wing and tail, presumably where feathers had been lost and replaced.

All of the primary tips are heavily abraded in this picture,
in addition the first secondary has been replaced - March 2011
(T D Codlin)

Heavy abrasion was also present on the tail feathers, however one feather within the tail had been replaced, thereby providing a contrast between the unmoulted juvenile feathers and the new adult feather.

The longer, darker coloured and unworn adult feather
is clearly obvious within the tail - April 2011 (T D Codlin)

By contrast the next bird captured was an adult, the colouration of the feathers and the lack of noticeable wear on the wing tips confirms this bird as being an adult.

Adult chiffchaff wing, note the emargination on the 3rd, 4th, 5th
and 6th primaries and the wing point formed by the 3rd, 4th and 5th 

primaries - April 2011 (T D Codlin)

The next bird captured was a willow warbler, at least three singing males and one female were present. In willow warblers the moult strategy is completely different to chiffchaffs, in that both adult and juvenile birds undergo a complete winter moult. Therefore it is not possible to age birds in the spring since both adult and juvenile birds will have replaced all their feathers.

Willow warbler, note the strong supercilium and more robust,
 longer bill, paler underparts and longer primary projection
beyond tertials - April 2011 (T D Codlin)

As well as having a different moult strategy, willow warblers also have a different wing formula and a longer wing.

This willow warbler wing shows the wing point formed by the 3rd and 4th
primaries only, unlike with chiffchaff, and on close examination it is possible
to see that only primaries 3, 4 and 5 are emarginated, and not the 6th as in
chiffchaff - April 2011 (T D Codlin)

In all, three chiffchaffs and a single willow warbler were captured along with two long-tailed tits, but the highlight was the two lesser redpolls. I have very rarely captured this species, and so was very pleased with these two birds. The published literature states that in spring quite a few birds cannot be aged, but it should be possible to age extremes. In juvenile birds the tips of the tail feathers are abraded and sharply pointed......

First year lesser redpoll showing paler more abraded and
pointed tail features - April 2011 (T D Codlin)

...... whereas adult birds have tail feathers rather fresh.

Adult lesser redpoll showing more rounded and
fresh tail feathers - April 2011 (T D Codlin)

Luckily it appeared that I had two extremes, as both birds seemed to be fairly obvious to age.

Saturday, 2 April 2011

Manor Farm Country Park - 2nd April 2011

They say that one swallow doesn't make a summer, well I wonder how many does? 

Today I returned to Manor Farm Country Park in Hampshire for some spring bird ringing and  the hope of catching some house sparrows for my ongoing RAS project. I only put up five nets as I was with a colleague who needed some training, but the usual sparrow nets were put up as they were my priority. Our first bird, surprisingly, was a second year female blackcap, which was my first ringed in the UK this year. As we continued with our first net round, two blackcaps and two chiffchaffs were noted singing; as I haven't been here for a few weeks I don't know how long they have been at the site, but suspect that they had arrived this week.

As I was extracting a sparrow during our second round I heard the familiar call of the barn swallow, and there above us were two swallows...... does that mean summers here? I was then distracted from the swallows by the frantic alarm calling of the resident starlings and jackdaws, and there above me a red kite slowly drifty west over the site. I haven't seen this species at the park before, but they have become much more common in Hampshire in recent years. I wonder if this was this one of the recent colonists or a newly arrived migrant?

I previously used to colour ring the house sparrows that I captured as part of my RAS project, but the little critters used to remove the odd ring making it impossible to decipher the different colour combinations, so I gave up. But I recently ordered some new darvic rings from a company in Poland, these rings are coloured and have three digits on them. These rings are overlapped making it very difficult for birds to remove, therefore it seemed like a good time to resurrect the colour ringing part of my project, as this massively increases the number of retraps seen each year.

Coloured Darvic Rings Used as Part of my RAS Project

Birds captured as part on my RAS project will be ringed with a single letter and two numbers on a yellow coloured ring, this ring will fitted on the left tarsus; a metal BTO scheme ring will be on the right trasus. Unless you live within a mile of Manor Farm Country Park it is unlikely that you will see one of my birds, as house sparrows are fairly sedentary, but you never know, so keep your eyes peeled.

After four hours ringing we had amassed a total of 23 birds, 15 new and eight retraps. The new birds included six house sparrows, the blackcap, a chiffchaff, blue and great tits and a  cracking adult male greenfinch. The retraps included a robin, a long-tailed tit and a four year old dunnock.
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