Friday, 9 August 2013

Phenotypic Divergence in Reed Buntings

A while back, I was taking some additional biometric data on Reed Buntings for a project being conducted by a friend, Júlio Neto - I mentioned it in this post. The article was completed last year and was published earlier this year, in May. You can read the abstract here:

Phenotypic Divergence among West European Populations of Reed Bunting Emberiza schoeniclus: The Effects of Migratory and Foraging Behaviours.

Divergent selection and local adaptation are responsible for many phenotypic differences between populations, potentially leading to speciation through the evolution of reproductive barriers. Here we evaluated the morphometric divergence among west European populations of Reed Bunting in order to determine the extent of local adaptation relative to two important selection pressures often associated with speciation in birds: migration and diet. We show that, as expected by theory, migratory E. s. schoeniclus had longer and more pointed wings and a slightly smaller body mass than the resident subspecies, with the exception of E. s. lusitanica, which despite having rounder wings was the smallest of all subspecies. Tail length, however, did not vary according to the expectation (shorter tails in migrants) probably because it is strongly correlated with wing length and might take longer to evolve. E. s. witherbyi, which feed on insects hiding inside reed stems during the winter, had a very thick, stubby bill. In contrast, northern populations, which feed on seeds, had thinner bills. Despite being much smaller, the southern E. s. lusitanica had a significantly thicker, longer bill than migratory E. s. schoeniclus, whereas birds from the UK population had significantly shorter, thinner bills. Geometric morphometric analyses revealed that the southern subspecies have a more convex culmen than E. s. schoeniclus, and E. s. lusitanica differs from the nominate subspecies in bill shape to a greater extent than in linear bill measurements, especially in males. Birds with a more convex culmen are thought to exert a greater strength at the bill tip, which is in agreement with their feeding technique. Overall, the three subspecies occurring in Western Europe differ in a variety of traits following the patterns predicted from their migratory and foraging behaviours, strongly suggesting that these birds have became locally adapted through natural selection.

The full article can be found here.


Monday, 20 May 2013

And we're off!

This weekend we managed to get back out to Brook Vale, joined by Nigel, Finn and Dan. Whilst last weeks efforts were focused on the RAS, with the half term looming, I wanted to get another session in on Rimrose ahead of a session at Fulwood next week.

The reedbed is starting to recover from Easters act of vandalism and the remaining reeds are alive with singing Reed Warblers and the first Sedge Warblers at the site this year. Sadly, Fulwood also got burned pretty bad - the worse it's been hit in the last few years. In an arson-free year, the area would support upwards of twenty five pairs of Reed Warbler and the margins a further fifteen pairs of Sedge Warbler but there will only be a fraction of that this year.

Sedge Warbler (Acrocephalus schoenobaenus)

Back at Brook Vale, it was a typical session for this time of year - plenty of bird song with Blackcap, Whitethroat and Reed Warbler in full song as well as the first Willow Warbler I've heard there this year which we later caught and ringed. We ringed our first two Reed Warblers for the year, a further two Sedge Warbler and caught the Spanish-ringed Blackcap again.

Dan further indulged his fondness for Woodpigeons, finding and checking this nest with two eggs. It was a good opportunity to introduce Finn and Dan to nest recording, which lead on to our exploits in the afternoon.

Dan checking the Woodpigeon nest

Wren -   1
Willow Warbler -   1
Chiffchaff -   2
Blackcap -   3
Whitethroat -   2
Reed Warbler -   2
Sedge Warbler -   2
Dunnock -   1
Blackbird -   6

TOTAL:   20

In the afternoon, we headed out to into the wilds of South-west Lancs to check a number of our nest boxes for Tawny Owl, Jackdaw and Stock Dove. First stop, we had a Tawny Owl on one egg, a Kestrel sitting on five, a Mallard on the bales and two very grubby Stock Doves chicks found by Dan. This is the second species that Dan has ringed as pulli, his first being a good session of Swallows last summer. The second site usually has Kestrel breeding and in recent years, the Barn Owl nest box has been overtaken by Jackdaws. This year, we found three nests of which two were occupied both with three chicks but only one brood were big enough to ring. The final stop of the afternoon was to check a Tawny Owl box, there was only one chick this year, but it was in good condition.

Jackdawn (Corvus monedula)

Elsewhere, Moxey has been keeping an eye on developments at Hightown fields, the Wheatears have all but dried up on the asparagus fields but over the road, he's managed to ring a total of fifteen chicks this week!

Jackdaw -   3
Stock Dove -   2
Tawny Owl -   1
Lapwing -   15

And so, we're off the mark with the pulli this year!

Sunday, 12 May 2013

Out on the RAS

On Saturday, me and Moxey were accompanied by Dan as we completed our first session of a new project we're working on. In recent years, we have caught significant numbers of Blackcaps and although most of these have been caught on migration at sites on Rimrose Valley, ringing sessions at some of our woodland sites have revealed a significant breeding population. With this in mind, we decided to apply to complete a RAS project on this Blackcap population at Ince Blundell.

The aim of a RAS (Retrapping Adults for Survival) project is to provide information on adult survival rates and with that in mind, there is a long-term focus to enable the calculation of long-term survival trends. In order for the project to return the required thirty-plus recaptures from previous years, we'll need to ring at least fifty breeding adults. As this is the first year that we're running the RAS, this is very much our 'pilot' year to see whether we can capture the required number of adults to make the project viable.

During this weekends sessions, the total number of Blackcap caught stood at eight, one of which was a BTO control - this leaves us with two controls in one week following Mondays capture of a Blackcap at Brook Vale bearing a Spanish ring. The weather this weekend has been poor, limiting our sessions so over the next few weeks we'll complete our circuit of the woodland attempting to catch as many of the breeding Blackcap as possible.

Blackcap (Sylvia atricapilla)

Thursday, 9 May 2013

Hablas español mate?

It's been a little quiet on the blog lately, so I thought I'd bring you up to date with a quick round up of the Bank Holiday Weekend's activity.

We managed three ringing sessions over the course of the weekend, starting at Kings Moss on Saturday, Hightown on Sunday and Brook Vale on Monday. In truth, the weekend was pretty quiet - Kings Moss and Hightown yielded little with the latter showing a distinct absence of birds that you would expect to be breeding at this time, namely Blackcap and Chiffchaff. Hightown did provide the first Sedge Warbler of the year however:

Sedge Warbler (Acrocephalus schoenobaenus)

The majority of the birds were caught at Brook Vale on the Monday. I arrived first and set the nets and by the time Moxey arrived I'd already caught four Blackcap, including one already bearing a ring. Similarly to the Sedge Warbler caught at Hightown last year with a French ring, it was immediately clear that this bird was a 'foreign'. Upon closer inspection, the ring read the inscription showing that it was an ICONA MADRID bird, the ringing group's first Spanish-ringed Blackcap!

ICONA MADRID

Female Blackcap (Sylvia atricapilla) - pollinated

Later in the ringing session we caught the first two Reed Warblers of the year, caught in the small amount of reeds that remain following a burn during the Easter holidays. Both of these birds were ringed at the site last year as adult birds and there were at least seven singing birds around the ringing site.

 Reed Warbler (Acrocephalus scirpaceus)
 
The session also provided the first juvenile bird of the year, a recently fledged Blackbird.

Juvenile Blackbird (Turdus merula)

Wednesday, 24 April 2013

Better Late Than Never

On Saturday I headed to Hightown for a session in the dune slack. The outlook was for a glorious day and despite a relatively frosty start, the sun soon woke up and the temperature rose. With the Sun began the bird song and at least five Willow Warblers were calling from various stands of willow, there was the scratchy warblings of a single Whitethroat near the railway and there were numerous Blackcap singing.

It took me slightly longer to set up by virtue of being by myself, but once the nets were up, I was kept relatively busy. The early net rounds yielded a good number of Blackcap and three Willow Warblers, two of which were males returning from the previous year. We are able to sex most Willow Warblers based on their wing length as they are sexually dimorphic - these two had wing lengths at the top of their range 72 and 73mm respectively.

As the morning progressed, the Chiffchaff started to appear in the nets despite there being little song from them, which is something that I have noticed so far this year in addition to the fact that we are a long way off our total at this time last year - the same is true of Blackcaps.

Mid-morning saw the most interesting net round of the day. Things had already started to quieten down, which is common, and only two birds were caught. The first was a Lesser Whitethroat, the first we have caught for two years and the first at this site. The second was a Grasshopper Warbler, caught in the middle of the willows, quite high in the net which most ringers will appreciate is not typical Grasshopper Warbler behaviour.

Lesser Whitethroat (Sylvia curruca)

Grasshopper Warbler (Locustella naevia)

The last bird to be ringed was the first Whitethroat of the year. Following the disasterous breeding season last year, demonstrated through the use of CES data collected by ringers and analysed by the BTO, Whitethroats were victim to a massive drop in productivity (based on young fledged) that has been attributed largely to the weather conditions.

Whitethroat (Sylvia communis)

There was a good deal of butterfly activity during the course of morning, with Speckled Wood and Small Tortoiseshell observed, but the most abundant were the Peacocks.

Peacock (Inachis io)

Willow Warbler -   3   (2)
Wren -   2   (1)
Chiffchaff -   5
Goldcrest -   4
L.T.Tit -   1   (1)
Lesser Whitethroat -   1
Grasshopper Warbler -   1
Blackcap -   12
Robin -   1   (1)
Coal Tit -   1
Great Tit -   1
Whitethroat -   1
Siskin -   1
Blackbird -   2   (1)

TOTAL:   36   (6)

Later in the day, I had to head out to Halsall to pick up three new sheep for the school farm. We decided to go with the Zwartbles, originally from the Netherlands, and pretty fine ladies they are too! I took an hour or so to take a walk along the Leeds-Liverpool canal at the Saracens Head. During this brief stroll I had my first House Martins, some more Swallows, Willow Warbler, Whitethroat and the first Reed Warbler of the year.  

Monday, 15 April 2013

Green Shoots?

This Saturday it was only me and Moxey that were available so we headed up to Kings Moss. On the last few feeding sessions that we'd done during the week, there were still a significant number of Brambling using the feeding stations. After a couple of days of clear weather, the chances of a few migrants were also high.

If this spring could be typified in one moment, it would be extracting a Brambling in the net that was next to a Willow Warbler. This Willow Warbler was the first we've caught so far this year and there were at least three singing during the morning. There wasn't many Chiffchaff singing but two were caught and one other seen in the vicinity of the nets but this bird wasn't caught.

 Willow Warbler (Phylloscopus trochilus)

The stand-out feature of the session was that more than half the birds ringed were Brambling. With only one retrap caught, this indicates that there is still a high turnover of birds in the area. Most of the birds were carrying ESF fat scores of at least 2 with most carrying 3 or 4, the heaviest bird weighing in at 29.6g - no where near some of the whopping Chaffinches caught by Dave Hallam in South Yorkshire last week.

Elsewhere we had our first butterfly of the year, a Peacock, and the cowslip is also starting to emerge.

Cowslip (Primula veris)

Chiffchaff -   2
Willow Warbler -   1
Lesser Redpoll -   5   (6)
Blue Tit -   1   (4)
Great Tit -   1
Chaffinch -   1
Brambling -   17   (1)
Coal Tit -   (2)
Yellowhammer -   1
Willow Tit -   1
Reed Bunting -   1
Greenfinch -   1
G.S.Woodpecker -   1

TOTAL:   33   (13)

There was no chance of ringing on Sunday morning due to a combination of wind and rain. This evening when heading up to do the feed, I had the first Swallow at Windle and a Small Tortoiseshell at Kings Moss. The green shoots of spring are showing their faces!

Tuesday, 9 April 2013

Wilde About Worms: A few migrants

Sunday was the last ringing session of the Easter holidays for me and I was joined at the Woodhams by Nigel, James and Findlay (who took great pleasure in reminding me that he had another week of holidays and would be birding in Wales whilst I was in work). It might have something to do with this picture I posted of him last week.

The last few ringing sessions, we've been catching a increased number of Robins - there seems to be a bit of an influx of unringed birds into the usual territories. With that in mind, I sent a text to Nigel on Saturday night telling Finn to dig up some small worms to bring to the ringing session. And so after all of the nets were set up, I challenged Finn to catch me a Robin without using a mistnet, this is what he came up with:


I was slightly more successful however, picking up another four Robins although I did have the help of a couple of spring traps!

Elsewhere in the woods, there was precious little evidence of any movement. As with Kings Moss the day before, there was no real evidence of vegetative growth on the trees although a few of the elder bushes had started to come out in leaf. Despite this, we did pick up our first Blackcap of the year, a male that weighed in at 20.9g with ESF 4 and a pectoral muscle score of 3 - this bird will probably keep moving North.

 First Blackcap (Sylvia atricapilla)

We also increased our ringing totals for Chiffchaff, with a total of four birds caught, all males based on their wing length (61-63mm). All of the Chiffchaff had shown evidence that they had been feeding on pollen, showing congealed on the feathers above the beak.

Chiffchaff (Phylloscopus collybita)

The feeding stations didn't yield much in the way of finches, but did turn up a single Lesser Redpoll, an adult male, only the second Lesser Redpoll to be caught at the site.

Lesser Redpoll (Carduelis cabaret)

A female Sparrowhawk was seen carrying prey, by the size of the bird it was probably a Robin or a Dunnock and it was encouraging to see it hunting in this area. The flock of Curlew on the adjacent fields numbered between 160 and 200 although they were pretty spread out between our location and the Ackers Lane.

Goldcrest -   3
Chiffchaff -   4
Blue Tit -   2   (10)
Great Tit -   (5)
Coal Tit -   (1)
Robin -   4
Dunnock -   (2)
Lesser Redpoll -   1
Goldfinch -   3
Chaffinch -   2
Blackcap -   1
Greenfinch -   4
Nuthatch -   (1)
Blackbird -   3

TOTAL:   27   (19)