Thursday, 23 March 2017

Mirror mirror on the car: part 3

The Dunnock was full of the joys of spring again this morning and doing his best to impress. I couldn't see if he was showing off to a female as he was on the far side of the car, near the hedge, and only visiting the wing mirror on that side of the car. I can only presume a female was skulking around there, somewhere.

As he was putting on a regular performance at the same wing mirror I decided to try and get some video. He was sat by the window of the drivers door when I went to the car and only flew off when I opened the passenger door to set up the camera. It only took a couple of minutes to get set up and the Dunnock returned to the wing mirror and started performing almost as soon as I went back in the house. I went out and repositioned the camera a couple of times and the bird returned almost immediately each time. Three of the best clips have been edited together and can be seen in the video below. Unfortunately the camera didn't pick up any sound through the closed window.


The car wing mirrors seem to be a big part of his courtship behaviour now so I am not going to cover them or close them in just yet but I will keep an eye on the situation. It will be interesting to see if his behaviour continues as we get further into the breeding season and if it brings him any success with the ladies.

Wednesday, 22 March 2017

Mirror mirror on the car: part 2

The Dunnock was at it again this morning but it soon became apparent it wasn't a simple case of a bird attacking its own reflection in a mirror, far from it. Dunnocks have complex mating systems and may be monogamous (pairs), or engage in polyandry (two or three males with one female), polygyny (one male with two females), polygyandry (two or three males sharing two three or four females). The behaviour of this particular bird appears to add another variation to those mating systems.



When I saw it by one of the car wing mirrors again this morning it would have been easy to assume that it was simply treating its own reflection as an intruder, which is what I had thought the other day. The difference today was that I noticed there was another bird nearby, presumably a female. I watched for a while, taking photos as I did so, and realised it was seeking out and displaying to its reflection but only on the side of the car that could be seen by the female.


A grotty photo but then it was another miserable wet morning and it was taken through double glazing and two windows of a car. The other Dunnock was in the hedge which can be seen in the background.
As the presumed female Dunnock moved round the car so did the displaying male, seeking out its reflection as it did so. The wing flicking the bird engaged in was akin to that of displaying male trying to drive out an intruder but also that of a male in one of the complex mating systems involving more than one male. It didn't just use the mirrors and displayed to other reflective surfaces too.







Now this may seem far fetched but this bird seemed to be trying to impress the female by displaying to its own reflection in the absence of another male or males.

King of the car.







To try and confirm what was going on I covered the wing mirror on the far side of the car.



When the female Dunnock went to the far side of the car the male Dunnock went to the far mirror even though it was covered. This suggests its behaviour wasn't a simple reaction to the accidental encounter of its reflection. This bird seemed to have learned where it could encounter its reflection in relation to the position of the female and went there in order to impress the female.


What no mirror.
The fact that the male Dunnock went and sat in front of the covered mirror when the female was on that side of the car shows it was actively seeking out its own reflection and where, in the male Dunnock's mind, it would find a potential intruder/second male (in the form of its reflection) to react to and so impress the female. Now the thought of that is really interesting. This male Dunnock is effectively using the reflective surfaces of the car to display against in order to impress a female. Perhaps some male Dunnocks put on a better display if they perceive they are in a complex mating system rather than a simple monogomous relationship. How the female perceived this is anybody's guess, especially as she wouldn't have been able to see the reflections.

Monday, 20 March 2017

Mirror mirror on the car....

.....who's the most dominant Dunnock by far. It was a wet and miserable for much of this morning but that didn't put a damper on the antics of one of the garden Dunnocks. I glanced out of the kitchen window while making a brew and noticed one was attacking its reflection in the car wing mirror. I ran for the camera but when I got back to the window it wasn't there and I thought that was that but, luckily, it came back after a few minutes and I managed to get a few shots.


Looking out for trouble prior to an attack.












The garden Dunnocks have been frisky for a while now and can often be seen going around in twos and threes and displaying by waving their wings at each other or chasing each other around but I have never seen one attacking its reflection before. Given the angle of the wing mirrors it is hard to understand how it got into a position to see its reflection in the first place and what made it more interesting was that it also went round to the other side of the car and attacked its reflection in the other wing mirror too. It only stopped this behaviour when another Dunnock appeared and it chased after that bird. I will keep a look out from time to time over the next few days to see if it engages in this behaviour again and if it does I will have to get into the habit of closing in the wing mirrors.

Wednesday, 15 March 2017

First Chiffchaffs

I went up to Billinge this morning and set 3 nets in the north east corner of the site. I didn't expect to catch much but there were a few more birds around than I expected. Goldcrests led the way with 6 ringed and a 7th escaped from one of the nets before I got to it. All the Goldcrests will have been migrants and 2 were quite fat and weighed 6.2 g. The two heavy birds also had well demarcated pale grey napes which suggests they are of continental origin, they will have a long way to go to get back to their breeding grounds.


Goldcrest
A Chiffchaff was singing not far from the nets and was my first of the year. This particular territory is usually the first to be occupied and I could see the bird was ringed so is likely to be the territory holder from last year. While the singing bird didn't find its way into the nets another male Chiffchaff did; this was an unringed bird which was a bit of a surprise as the first returning birds are nearly always retraps.


Chiffchaff
There was surprisingly little in the way of passage overhead and what there was didn't amount to much more than 3 Meadow Pipits going north. However, a lone Crossbill flying west north-west mid morning was a good spring record and made up for the general lack of numbers.

Ringing totals (retraps in brackets) were: Goldcrest 6; Chiffchaff 1; Long-tailed Tit 2 (1); Blackbird 1; Robin 1; Bullfinch (1). Total 11 new birds and 2 retraps.

Tuesday, 14 March 2017

Comma

I have yet to see my first summer visitor of the spring but an increasingly sunny and warm afternoon produced my first butterfly of the year in the form of a Comma. I was having a late lunch and saw it dart across the garden out of the corner of my eye and settle on the Box hedge. I didn't have a camera to hand and by the time I got one it had gone. Luckily it returned a minute or so later and sunned itself on the Box hedge and the lawn before departing once more. Interestingly it returned a second time and sunned itself in the same spots before heading off again.


Comma 14/03/2017

Comma 14/03/2017
On the bird front I had put a net up in the garden this morning and caught 10 new birds in just over half an hour - 8 Siskins, 1 Goldfinch, 1 Goldcrest and just 1 retrap, a Siskin. There is a steady turnover of Siskins at the moment so I try and get a net up 2 or 3 times a week, if conditions allow, but I keep the ringing sessions short. The garden is a bit of a sun trap, as the Comma showed, so I only put a net up if it is overcast and there is little or no wind and it had been like that earlier. This little and often approach can be more productive than longer and less frequent ringing sessions in my small garden.

The forecast is looking good for the morning so I may go up to the site at Billinge to see if I can connect with a Chiffchaff or a Wheatear or better still, both.

Saturday, 11 March 2017

Recent recoveries.

A few recoveries have trickled in recent weeks and while some of the birds involved hadn't gone very far they are interesting nevertheless.

S552233       first year      Coal Tit   (black pin on map)
Ringed          22/10/2016  Billinge Hill, Merseyside.
Controlled     21/01/2017  Woolston Eyes, Warrington. 18 km SSE, duration 91 days.
A total of 52 Coal Tit were ringed at Billinge Hill last autumn with the majority being ringed in September and October when there was an obvious southward dispersal/movement. The recapture of this bird at Woolston Eyes is the first recovery to show the destination of any of these birds.

HPV497        full grown     Long-tailed Tit   (blue pin on map)
Ringed          05/10/2014  Billinge Hill, Merseyside.
Found dead  04/03/2017  Prescot, Merseyside. 13 km SWW, duration 881 days.
This is the first movement away from the ringing site and it was found dead under a window.

JDH819       adult male    Goldcrest   (yellow pin on map)
Ringed         01/10/2015  Billinge Hill, Merseyside.
Controlled    29/10/2016  Hilbre Island, Wirral, Merseyside. 38 km WSW, duration 394 days.
This bird will have moved much further than the 38 km between the two sites. It was caught when on passage at Billinge and similarly when controlled on Hilbre Island the following year and probably originated from northern England or Scotland.




A couple of recovery reports for Siskins were also received and illustrate the mobility of the species.

D874496      first year female   Siskin
Ringed         18/03/2014   near Orrell, Greater Manchester.
Controlled    14/02/2017   Witton-le Wear NR, Durham. 143 km NNE, duration 1064 days.

S192064       first year male     Siskin
Ringed          11/04/2016   Peebles, Scottish Borders.
Controlled     07/03/2017   near Orrell, Greater Manchester. 293 km S, duration 330 days.




Siskins are an variable migrant and move further in some years than others in response to fluctuations in natural food supplies. There was a major irruption of Siskins in autumn 2015 but fewer were on the move last autumn and that is now being reflected in the numbers coming to the feeders in my garden. In 2016 I ringed 118 up to 11th March but have only ringed 64 over the same period this year. It will be interesting to see how numbers compare later in spring although I expect numbers will remain about 50% down on those of last year.

Thursday, 2 March 2017

Ageing Goldfinches gets more interesting.

This is a post for aficionados of moult, ageing birds in the hand and Goldfinches in particular but hopefully it will be of interest to others too. First year Goldfinches normally only have a partial post-juvenile moult in the UK and this usually involves the replacement of the body feathers along with most of the upper wing-coverts and tertials, and may also include some of the tail feathers. However, first year birds from populations in southern parts of Europe frequently have a more extensive post-juvenile moult which involves more of the upper wing coverts and can include some or nearly all of the flight feathers. Whether any actually have a complete moult, like adults, is open to question but if some do it may only be a fairly small proportion. It is probably better to think of it as an unknown proportion as it is an aspect of moult that is difficult to study so may be more common than the literature suggests.

Much of the literature on this subject is quite dated now and many ringers in the UK will have had experience of first year birds that have undergone a more extensive post-juvenile moult than was the case say 20 or 30 years ago. When I started ringing it used to be relatively rare for Goldfinches and Greenfinches to replace all their greater coverts as part of the post-juvenile moult but things have changed and it is much more common these days. That tendency for a more extensive post-juvenile (pj) moult hasn't stopped there and some Greenfinches also started replacing a few primaries as part of their pj moult. The inclusion of some primaries in the pj moult of British Goldfinches followed and there have been recent reports of first year Goldfinches undergoing a complete moult like adults. In a couple of cases that I am aware of the birds were ringed when they were in juvenile plumage and were considered to have undergone or were just finishing a complete moult when they were retrapped later in the year. I don't know how thoroughly these birds were scrutinised when they were retrapped but one of the reports suggested the extent of the moult was noticed at the time of recapture rather than being assumed from an age discrepancy on checking the original ringing details.


So where am I going with this and why is it interesting. Well I caught a Goldfinch yesterday that had undergone a very extensive post juvenile moult and it only just fell short of a complete moult. It had undergone the most extensive pj moult I have ever seen in the species and is the sort of bird that could get overlooked unless all the feather tracts are carefully examined. It had replaced nearly everything and the few feathers it hadn't replaced were not very obvious and are easier to see in the photographs than they were in real life. I had to turn the bird so the feathers caught the light just right and also played with the exposure setting on the camera to be able to show the differences between the moulted and unmoulted feathers. So lets have a look at it ......



I have included this photo to show that the moult limit in the primaries was not that easy to see. The outermost primary in the image is just that bit browner but remember this image is larger than life size. Also, and more importantly, the bird was held at just the right angle to the light to try and make the difference stand out.
Close the wing a little bit and adjust how the feathers catch the light and the difference is a bit easier to see.


Zoom in even closer and you can see the outer feather is a little more worn in addition to being brown but as the wear is relatively slight and the feather is not that bleached it rules out the possibility of it being an adult that has arrested its moult.
Here I have to admit that I thought the bird had replaced all of its primary coverts on the right wing when I examined it and only noticed that it had just replaced the inner 6 on reviewing the photographs. The contrast between the new and the old feathers wasn't as obvious in real life as it appears in this heavily cropped photo. Because of this oversight I didn't check the primary coverts on the left wing.
Zoom in a little more and it doesn't make the difference that much easier to see. The 7th and 8th primary coverts were unmoulted and the 9th (if Goldfinches do have a 9th primary covert) is so small its very difficult to see never mind age.

So here we have the left wing. I had to show it this way up as I can't use the camera in my left hand. The two outer primaries in this image just look a a tiny bit browner and the shape formed by the primary tips isn't quite right.


Crop in closer and you can see the outer two primaries in the image are browner, unmoulted juvenile feathers.
Zoom in further and the difference in colour is still obvious but the old feathers are only a little more worn. So it has moulted asymmetrically but only by 1 feather.
I was a bit less certain about the age of the tail feathers although I do think all the tail feathers have been replaced. There only appeared to be one generation of tail feather as there was no detectable difference in the intensity of the black between any of the feathers. They were too fresh looking for juvenile feathers although the 3rd, 4th and 5th tail feathers were a little bit more worn and pointed than I would have liked but then we have to bear in mind that it is March, if only just, and the tail feathers of adults are starting to show signs of wear at this time of year. If these were unmoulted juvenile feathers I would expect them to be far more worn and pointed and a little less glossy too. It is fair to say that it is not the most convincing adult type tail but then it doesn't look like a totally convincing first year tail either. 

This image shows all the tail feathers and the outermost (6th) tail feather on both sides appears to be very slightly less glossy black but this is an artefact caused by the light acting on the angle of the tail feathers. I just couldn't keep the tail totally flat so some of the feathers are in a slightly different plane and that affects their appearance. The shape of the feathers is just within the range shown by adult type feathers and I do have photographs of a known age adult with a similarly shaped tail. It was the appearance of the tail that initially set the alarm bells off in my head and caused me to have a really good look at this bird.


In this image we get a much closer look at the tips of the tail feathers and that wear. The tips of the feathers on the left side of the tail are slightly less worn than those on the right but it is marginal and not that unusual. The wear is fairly even within each half of the tail and supports my view that there is only one generation of tail feathers. The black portion of feathers  5L, 6L, 4R, 5R and 6R appears to be less glossy black than the other feathers but again it is simply an artefact of the light and is also a camera focus and depth of field issue rather than it being anything age related.


The tertials were interesting in that there was some uneven wear of the white tips with the middle tertial being a bit more abraded than the other two. They are all the same glossy black so they have all been replaced but the white tip of the middle tertials are showing more signs of wear. The white tips of the tertials in this bird are a little more worn than you would expect to see on an adult, even though they have been replaced like those of an adult, but that is probably because a first year undergoing an extensive partial post-juvenile moult will have started moulting earlier than an adult undergoing a complete moult. The replaced feathers on this bird could be up to a month or more older than those of a fully moulted adult and therefore should show more signs of wear. This difference in age of the new tertials on this bird compared to those of an adult may also explain why the tail is as worn as it is.



Here is an image of the right wing which clearly shows all the feathers are new apart from the outer primary and primary coverts as detailed above.

And here is the whole bird and it is a nice male it is too, not that its sex has any bearing on the extent of the pj moult.

So why is any of this interesting and why does it matter? Well, if it becomes the norm for some first year Goldfinches to have a complete moult then those that do will be indistinguishable from adults and potentially make it unsafe to age any Goldfinch as an adult. The error rate at the present time is likely to be small but it is unknown quantity and may not be as small as we would like it to be. Opinions will vary as to the level the error rate needs to reach before ageing Goldfinches as adults is considered to be too unreliable but we have to prove to what extent it is happening first. Unfortunately finding this evidence is intrinsically difficult for reasons I won't bore you with now but the fact that these juveniles become indistinguishable from adults is no small hurdle in itself.

The best evidence will come from retraps and some of that evidence may already be out there in the form of age discrepancies between the time of ringing and recapture. An indication that some birds are having a complete moult will come from birds that have been ringed when they are in juvenile plumage and and are aged as an adult when recaptured later in the birds first year of life. If this type of discrepancy becomes more common it potential points to more first year birds having a complete moult as opposed to errors in data recording and ageing. So what may initially appear to be a cock up could actually be a useful piece of evidence.

Another reason the change in the extent of post juvenile moult matters is that it is probably linked to climate change. Research is showing that some summer visitors are arriving earlier and a range of species are breeding earlier. The factors that are influencing those changes are likely to be involved with the tendency for some species, such as Goldfinches, to have a more extensive pj moult. Monitoring pj moult in a systematic way across a range of species could prove to be worthwhile and could be another useful indicator for demonstrating the effect of climate change.