Wednesday, 29 February 2012

Abnormal Plumage in Birds

In December 2011 the British Trust for Ornithology (BTO) launched their abnormal plumage survey, where they asked volunteers taking part in their Garden Birdwatch Survey to record birds with abnormal plumage. The aim was to see which species were affected most frequently, in what way and where they were most frequently recorded. I have been keeping an eye on this survey which has thrown up some pretty amazing looking birds, in particular the European Robin with a white breast and the stunning Blue Tit with a black head, and so I thought I would show off some of the usual birds I have seen in the last couple of years. Some of these images I have posted before, so apologies if you haven seen them, but I thought it would be good to have them all together in one post.

I thought I would start with the most striking, and this amazing Blackcap which was Captured on September 2010 at Titchfield Haven. As you can see the all of the primary, primary coverts, secondary, and tertial feathers are virtually pure white, whereas the tail feathers are darker on the shaft and towards the upper tail and there are a couple of white feathers in the crown.

Blackcap 18th September 2010 - Titchfield Haven

An amazing looking bird....

Blackcap 18th Septemebr 2010 - Titchfield Haven

The wing below is also that of a Blackcap which was again captured at Titchfield Haven, but on 22nd October 2011. This bird has three almost white primary coverts, and a white leading edge to some of the primaries,

Blackcap 22nd October 2011 - Titchfield Haven

This flock of Greylag Geese were seen up near Aldermaston in December 2011. In all there were 74 birds present but three of them were leucistic, with all of the coloured plumage washed out, whereas the undertail was still pure white as expected.

Greylag Geese, December 2011 - Aldermaston

Regular readers to this blog will have seen this Great Tit, which I caught in my garden on 28th October 2011. As you can see, this bird had an almost white tail, but overall the plumage was very washed out, with paler patches on the mantle and crown.

Great Tit, 28th October 2011 - Fareham

A finally this Grasshopper Warbler, which was captured on 14th July 2011 at Titchfield Haven. 

Grasshopper Warbler, 14th July 2011 - Titchfield Haven
It had pure white outer four primaries, primary coverts and a paler edge and tip to the alula.

Grasshopper Warbler, 14th July 2011 - Titchfield Haven

All in all quite an interesting collection, with some of them being species that you would not normally encounter in a garden.

Saturday, 25 February 2012

Manor Farm Country Park - Bird Ringing Again

The weather conditions were ideal for bird ringing this morning, flat calm, slightly overcast and as a bonus there was no frost!! We started early and had all the nets open by 6:30, and waited in eager anticipation.......and waited.....and waited! There was plenty of bird song in the air, with Song Thrush, Blackbird and Dunnocks all proclaiming their territories, and a mixed flock of about 100 Redwing and Fieldfare, but other than that there were very few birds around. But still we persevered and soon started to catch a few birds, two Robins, three blackbirds, a single Greenfinch and the usual Blue and Great Tits made up the bulk of the birds, and eight House Sparrows added to the information for my RAS project. My favourite bird of the day though was a Eurasian Treecreeper.

Eurasian Treecreeper

I have written about this species a couple of times before, and as they are such stunning little birds I thought that I would write about them again. There are two species of Treecreeper in the Western Palearctic, Eurasian and Short-toed, but it is only the Eurasian Treecreeper that is resident to the UK, therefore the likelihood of catching the a Short-toed is slim, nevertheless it is always worth checking!

Eurasian Treecreeper

It can be difficult to separate the two species since the plumage differences are slight and the biometrics overlap, but in most cases it is usually possible to easily identify a bird using a combination of features. Firstly, in Eurasian Treecreeper the lower edge of the prominent wingbar is more square edged or rounded, with a large and prominent pale spot forming the end of the wingbar on the fourth primary. In Short-toed the lower edge of the wingbar is more pointed and the spot on the fourth primary is either very small or even absent.

Eurasian Treecreeper

In addition the hind claw of Eurasian measures between 7.6 - 11.5mm, whereas it measures between 6.8 - 8.9mm in Short-toed. The hind claw on this bird was very long and well outside the range for Short-toed.

Long claws for gripping the bark of trees

So putting all the features together, this bird was clearly a Eurasian Treecreeper. 

Fine and pointed tool, ideal for locating food in the crevices in bark

In evolutionary terms Treecreepers are amazing, they have been perfectly designed to climb up the trunk of a tree, usually starting low down and working up to the spindly twigs at the top. The bill is long and thin and ideal for teasing out food from small crevices....

Rigid spiked tail....a third leg!
                            ...........and the rigid and spiny tail is used to rest against the trunk of a tree, providing extra support and acting as a third leg.

Eurasian Treecreeper

They are tiny birds, weighing around 8.0 grams, and their mottled brown colouration provides excellent camouflage, which is why the are probably heard more often than seen.   

Wednesday, 22 February 2012

Massacre on Mayles Lane!!!!

After another failed night out in search of Woodcocks, we headed home via a quick stop at the pub to drown our sorrows. We decided to take the short cut home and nipped down a private road called Mayles Lane, but had not travelled far before we were met with a scene of utter carnage!!!

Dead Common Frogs
Dead Common Toads

The road was absolutely littered with dead amphibians, including Common Frogs, Common Toads and Palmate Newts. I had only driven down this road earlier in the day and there were none here then, so presumably the heavy drizzle had prompted them to start moving out of the woods and to their breeding ponds, on the other side of the road.

Dead Common Toad

This road is only a minor country lane, but in total, along a stretch of road no more than 100 metres long, we counted 34 dead Common Toads, 5 Common Frogs and two Palmate Newts. 

Common Toad escaping the Carnage

We did manage to collect up a few live specimens and move them to the other side of the road, but in comparison three Common Toad, two Common Frog, two Palmate and a single Smooth Newt, was a paulty number compared to those that had been killed.

Palmate Newt

I have to say that I was very shocked to see such a large number of dead animals on such a quiet stretch of road, and extremely disappointed to see that people hadn't bothered to stop and move them out of the way. I think I m going to have to contact the local council and see if its possible to put a toad crossing in, or at the very least some signage!

Tuesday, 21 February 2012

Still no Woodcocks but a Little Owl saves the day.....

After a long day in the office I was keen to get out for some more nocturnal activity and so it was back Manor Farm. But rather that just trying to catch Woodcocks I decided to put some nets up with the hope of catching any passing owls, in particular the resident Little Owls. I set three nets and waited to see what would happen!!

Little Owl - February 2012

The first hour passed pretty slowly, Little Owls were around but proving to be elusive, so we decided to take the nets down and go off in search of Woodcocks, but as we approached the final net success.....a Little Owl!!

Little Owl - February 2012
Regular readers of this blog may recognise this bird, since it was a retrap that was originally captured one year and one day ago. In 2011 it was aged as an adult so it is at least two years old, looking at the first picture it didn't look very happy about being captured again!

Enthused by our success we trudged off around the fields in search of Woodcocks, but once again failed. We flushed six Woodcock and three Lapwing, but caught nothing......very frustrating!!!

Today, I had to travel to East Sussex for a survey, and as I walked around the site I managed to flush nine Woodcock, it was almost like they were rubbing salt into the wound!!! I continued with the survey, and noticed in an area of woodland the remains of another!! In the absence of any live specimens to examine, it gave me the ideal opportunity to have a go at ageing it.

Eurasian Woodcock Wing
Given that I only had nine primaries and seven primary coverts to work with I thought it might be difficult to age, but despite my limited experience with the species it seemed quite straight forward.

Eurasian Woodcock Primary Covert Tips

Apparently the tips of the primary coverts in adults have a flat profile with a pale terminal band, whereas juvenile coverts have a more rounded profile, with the terminal band the same colour as the rest of the above. The primary tips in adults show very little wear and have a clean profile, whereas they are worn and jagged in profile in below.

Eurasian Woodcock Primary Tips

Assuming I have aged this wing correctly it looks like this individual was a juvenile bird before it was eaten. I have no idea what had caught it but whatever it was, its having better success than me at catching Woodcocks at the moment!!!

Sunday, 19 February 2012

More Bird Ringing at Manor Farm

Another pre-dawn start and a clear sky made for a fantastic sunrise this morning. But the clear sky meant another heavy frost, although luckily not as heavy a frost as last week.

Sunrise over Manor Farm - I. R. Phillips

With the ground not as frozen there were loads more birds around, with the most numerous species being thrushes, in particular Redwing and Fieldfare; over 100 Redwing and at least 50 Fieldfares were present. I set nets in the usual places and was eventually rewarded with four new Redwing, but the Fieldfares as usual were too canny. In total we caught 8 different species during the morning session, with the most colourful being a pair of Goldfinch's. The male bird was a cracking adult, with a bright red face, forehead and chin. The red on the crown, which extended well past the eye, and the all black nasal hairs, confirmed this bird as a male.

Adult Male Goldfinch

The wing of this species is striking, with a strong contrast between the part jet black and part bright yellow primaries. Ageing is usually possible by the presence of a visible moult limit in the greater coverts, which was lacking in this bird....

Goldfinch Wing

                                     .......and the shape and broadness of the tail feathers which were broad and rounded in this bird, thereby indicating an adult.

Adult Goldfinch Tail

A new female Greenfinch was nice, but much duller in comparison to the Goldfinch's. This bird was a first year bird...

Female Greenfinch

                                  ................and was aged by the presence of a moult limit in the greater coverts, and the shape and colour of the tips of the primary coverts. In the image below it is possible to see the pale tipped greater coverts, and the pointed and pale tipped primary  coverts.

Juvenile Greenfinch Wing

In addition the tail feathers were very pointed and abraded, as illustrated below.

Juvenile Greenfinch Tail

The other species that we captured included single Blackbird, Wren and Great Tit, a couple of Blue Tits and five new House Sparrows. As I have mentioned before the House Sparrow is one of the target species for the site as I am studying the population as part of a BTO Retrapping Adults for Survival project. All of the birds captured are fitted with a BTO metal scheme ring on the right leg and a yellow colour ring with three figures, on the left if anyone is in the area keep your eyes peeled.

Colour-ringed House Sparrow

The session ended with a total of 17 birds captured, so not great but a nice variety for the trainees.

Saturday, 18 February 2012

Very frustrating......

It has been a very frustrating week this week which started on Monday evening with a visit to Manor Farm for a bit of Woodcock spotlighting. We trudged around the fields and eventually managed to flush 11 birds without catching one!!! We also nearly caught two Fieldfares, which bizarrely were roosting in the middle of a field....very frustrating!!

Wednesday night followed a similar pattern, in that we trudged around the same fields, this time flushing nine woodcocks and not catching one.....equally frustrating!! Hopefully better luck next week!

Adult Male Chaffinch

To try a salvage something from the week I put a net up in the garden yesterday evening, making use of the last couple of hours of daylight, and was rewarded with four retrap Blue Tits, a new Long-tailed Tit, two new Greenfinch's, a Goldfinch and a cracking adult male Chaffinch.

Adult Chaffinch

I never really spend much time looking at Chaffinch's in the field, but in the hand this bird was stunning. It was in full breeding plumage, with a rich chestnut back and mantle and a green rump, and the flight feathers were all fringed yellow.

Adult Chaffinch Wing

All of the flight feathers were extremely fresh, with no evidence of a moult limit in the coverts, and the tail feathers were very broad and rounded, showing little evidence of wear.

Adult Chaffinch Tail
When ageing Chaffinch's the tail is a crucial feature, with the central tail feathers being more rounded and sometimes having a black centre towards the tip, the 3rd tail feather (from the centre) is rounded, as is the 5th, which also has a well defined white patch and the dark parts are jet black.

Juvenile Chaffinch Tail

For comparison, it is possible to see the shape of the central tail feathers in a juvenile bird (pic above), note that one of the central tail feathers has been replaced, the juvenile feather is very pointed. Also the shape of the feathers in general is more pointed, and they are showing a fair amount of abrasion at the tips.

Sunday, 12 February 2012

Ringing again at Manor Farm Country Park

The weather conditions this morning looked ideal for ringing so I headed to Manor Farm for my first ringing session for a while. Once again it was freezing cold, and as I drove to the farm the temperature gauge in my car registered minus five!!! I am so glad I hadn't set the nets the night before as they would have been frozen solid. 

I was hoping that the cold weather would have brought in loads of thrushes, but in fact the frozen conditions had probably had the opposite effect and forced birds to move on. There were a handful of Redwing and Fieldfare present, single Grey and Pied Wagtails and not much else. But having made the effort I persevered and eventually ended with a total of 33 birds, including Blue Tit, Dunnock, Robin, Song Thrush, House Sparrow, Goldfinch and Greenfinch. The low number of birds around gave me the opportunity to concentrate on those that were caught, and it was just as well as in the end some interesting subjects were captured.

The first interesting bird was a Robin. The moult strategy in this species is typical of many European passerines, with adults undergoing a complete moult post breeding, whereas juveniles undergo a partial post juvenile moult. It is therefore usually possible to see an obvious break in the greater coverts between retained juvenile and moulted adult feathers in juvenile birds. But it is important not to be fooled by the variation in thorns present on the greater coverts (see below), which could be considered to be indicative of a moult limit. The example below seems to show an obvious break, but examining the ground colour of the feathers and the length and shape tells a different story.

Adult Robin

Referring to other features also pointed to something different; the broad and rounded tail feathers indicated an adult bird, and the all dark inside of the upper mandible the same. Luckily, this bird was a re-trap that had originally been ringed in November 2010 as a juvenile, and therefore it was possible to correctly age it as an adult...a very interesting lesson for the trainees present!

Adult Robin

Another species that always promotes discussion when trying to age it is the Dunnock, and today there was no shortage of them to discuss. According to Svensson (1992)(Identification Guide to European Passerines), ageing is possible in the autumn by way of eye colour and the paleness of the base of the lower mandible, whereas Jenni and Winkler (1988) (Moult and Ageing of European Passerines) suggest that the prominence and colour shade of light tips to the greater coverts and inner tertials is useful. Svensson is extremely cautious of this feature suggesting that the variation in different individuals is such that this feature should only be used by experts in the species. Two of the birds captured today illustrated perfectly why Svensson is skeptical of this feature.

Juvenile Dunnock Wing

This species again has a moult strategy which involves adults undergoing a complete post breeding moult, whereas juveniles undergo a partial juvenile moult, and therefore it may be possible to see a break in the greater coverts. The image above illustrates strongly pale tipped greater coverts, but what appears to be an obvious break where two darker and smaller tipped inner greater coverts are present. In addition the tail (below) is pointed and is heavily abraded, again  indicating a juvenile bird.

Juvenile Dunnock Tail

By contrast, the image below illustrates greater coverts that are not pale tipped and with no obvious break to indicate a moult limit...

Juvenile Dunnock Wing

                                               ......whereas the tail of this bird shows an obvious fault bar, a feature typical of a juvenile bird, and again the tail feathers are pointed and abraded.

Juvenile Dunnock Tail

As it happens both of these birds were again re-traps that were originally ringed as juveniles in the summer of 2011, and therefore are both first winter birds.

Adult Blue Tit

The session ended with another interesting record, this time a longevity record for the site, in the form of an adult Blue Tit. This bird was initially ringed on 11th July 2006, 5 years and 216 days previously; surprisingly the national longevity record for this species is 9 years, 9 months and 2 amazing age for such a small bird!

Saturday, 11 February 2012

Bunny Meadows again.....

The weather was fantastic today, full sun, flat calm but it was extremely cold...although not as cold as Norfolk last weekend!! Since I had been away last weekend, today was all about spending time with my wife, so we decided to go for a stroll along the shingle spit at Bunny Meadows, but not before a spot of lunch at a nearby pub. High tide was at 13:25 so we timed our walk to coincide with the last hour of the rising tide.

Roosting Waders Bunny Meadows

We arrived about an hour before high tide, just in time to see birds concentrated on the last remnants of inter-tidal mud before they were covered in salt water.

Dunlin and Wigeon

Around 200 Dunlin were feeding on the exposed mud, along with Wigeon, Greenshank and Grey Plover. The Dunlin were scattered around on the last remaining exposed areas of mud frantically feeding, whilst other species such as Grey Plover and Greenshank were opting for a quick snooze.

Dunlin and Grey Plovers

There were at least five colour-ringed Grey Plover visible on the mud but unfortunately I did not have my scope with me to allow me see the colour combinations, although zooming up on the photo above has enabled me to see three.

Greenshank and Dunlin

Five Greenshank and a single Black-tailed Godwit were present whilst two Grey Plovers roosted on the old wooden walkway.

Grey Plovers

I have tried to capture Rock Pipits at Bunny Meadows on many occasions, so I was intrigued to see that birds were very approachable on the shingle spit as the tide came in. 

Rock Pipit

In fact one bird kept walking up to me and I am sure it would have been attracted in by a well positioned meal worm in a spring trap.

Rock Pipit

Given the close views I was getting I thought it might be possible to age the birds present. Adults undergo a complete post breeding moult, whereas juveniles a partial moult and therefore I was hoping that it might be possible to see a moult limit within the greater coverts, but unfortunately there was nothing obvious visible.

Rock Pipit

A subtle cough in the background reminded me that I wasn't alone, so I packed up my camera stuff and continued my walk with my very patient wife.
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