Saturday, 31 May 2014

Exhausted Blue Tits

Blue Tits will occasionally pick some very strange places to nest in. This usually happens when natural holes in trees or nest boxes are in short supply. I was visiting one of my birding sites today when I noticed a Blue Tit carrying food towards a pumping station near to where I had parked. I got back in the car to use it as a hide and watched to see where the Blue Tits were going. It wasn't long before a Blue Tit returned with a beak full of caterpillars and landed on some kind of vertical exhaust pipe. It then dropped inside and came out a few seconds later. 

I repositioned the car to get some photos of the birds entering and leaving this unusual nest site. I have seen Blue Tit nests in street lights and uncapped sign posts but this is the first I have seen in an exhaust pipe.

Exhausting work rearing chicks and literally in this case. Sorry I couldn't resist.

I assume the exhaust pipe is part of some equipment that is no longer used or only gets used in certain circumstances. I just hope it doesn't need to be used before the chicks leave the nest.

Colourful and crafty Critters

Compact digital cameras often have really good macro capabilities and this has opened up an area of photography that used to be the preserve of specialist photographers with some very expensive kit. Whilst out ringing yesterday I spent some of the time photographing insects in between the net rounds as the catching rate was fairly slow. I used my compact camera in super macro mode which sets the lens to wide angel so the camera had to be within a few centimetres of the subject to get the shot and in many cases as close as 2 or 3 centimetres. Moving a camera that close to an insect like a damselfly without disturbing it isn't always easy but it can be done if you take your time.

Azure Damselfly (Coenagrion puella)

Azure Damselfly (Coenagrion puella)
Some sort of Weevil and colourful critter. I may get round to identifying it at some point.

Large Red Damselfly (Pyrrhosoma nymphula)

Large Red Damselfly (Pyrrhosoma nymphula)

Blue-tailed Damselfly (Ischnura elegans) eating a fly.

Blue-tailed Damselfly (Ischnura elegans) eating a fly.

Blue-tailed Damselfly (Ischnura elegans) eating a fly.
Whilst I was photographing the damselflies I couldn't help noticing bumble bees that were visiting the flowers of Red Campion. They weren't taking nectar in the conventional way via the open flowers but were making a hole at the rear of the flower to get at the nectar or tapping an existing hole. This nectar robbery allows short tongued bumblebees to get at the nectar in long necked flowers that they wouldn't otherwise be able to get at. Most if not all of the Red Campion flowers I checked seemed to have had nectar stolen in this way. I don't know how many bumble bees were involved but I suspect it was only a few or perhaps only one or two that were repeatedly visiting the same patches of flowers.

Red Campion showing signs of nectar robbery.

Caught in the act, bumblebee robbing nectar.
...and again, bumblebee robbing nectar.

....and again, bumblebee robbing nectar.

Sunday, 25 May 2014

Baby birds

This year seems to have the makings of a very productive year or at least it is starting out that way for some species. Having said that I have probably jinxed it now and we will be in for a miserable June and July but I hope not. Long-tailed Tits appear to be doing particularly well and many good sized broods are on the wing with some already joining together to form quite large flocks. Most of the other 'tit' species have recently fledged young in and it is hard to escape the noisy calls of the young birds along with the frantic food gathering activity of their parents. I haven't seen any young Blackbirds yet suggesting failure rates of local garden birds has been quite high so the picture is mixed as is often the case at both local and national level. Only time will tell and that is why ongoing monitoring is so important.

Unfortunately I have seen a lot of change in bird populations during my lifetime, some good and some bad, but most are man made in one way or another be it through climate change or changes in agricultural practices and the like. I would like to think I am not that old so these changes have been very quick in ecological terms and would have been very hard to imagine not that many years ago. Lapwings have disappeared from many farms in this area and have been all but lost from the remainder. The few remaining pairs rarely rear any young so local extinction is likely in the next few years.

On a more positive note this week saw the first juvenile Goldfinches following their parents into the garden. This is one species that is certainly on the up and has benefited from garden feeding, reclamation schemes and urban landscaping. Many pairs will have at least 2 or 3 broods so the garden should be full of them by September but that is only one increase in what is a sea of declines.

Juvenile Goldfinch
The once very common Starling is now red listed in the UK because of a recent rapid decline. I am lucky in that there are still quite a few nesting where I live although I have never been able to get a pair to use the nest box on the house. I attract a lot into the garden when they are feeding young by providing fat cakes and I have ringed about 50 adults this month and retrapped quite a few from previous years. I am considering starting a RAS project on them as I seem to have the ideal situation and population for this kind of project. RAS stands for Retrapping Adults for Survival and more information about RAS can be found here but it basically aims to establish the survival rates of adults to monitor and help understand population changes. It does require quite a lot of commitment over a number of years but as it only involves attracting local breeding Starlings to the garden it should be fairly easy for me to keep it going on a long term basis. Not quite armchair ringing but about as close as you can get. 

The number of young reared by each pair has increased as Starlings have declined but this increase in productivity per pair hasn't slowed their decline. This is because the survival rate of Starlings in their first year of life has halved over the same period and now only about 15% reach adulthood and get a chance to breed.
Only 1 of the 7 young Starlings in this picture is likely to survive the first year of life.

Sunday, 18 May 2014

A touch of 'nesters arm'

As the post title suggests I came home suffering from this condition yesterday afternoon. It was only a mild case caused by my efforts to check or find nests amongst hawthorns, brambles and nettles along with the glorious warm sunny weather and my resultant sleeveless apparel. Apart from a bit of mild tingling I didn't notice until someone said what on earth have you been doing when I got home.

Nettle rash combined with various minor cuts and a myriad of scratches but all in a good cause.
In the morning I had checked a Song Thrush nest in a tight hawthorn hedge which meant there was no easy way in or out for my arm. It contained small young so a repeat visit will be required in a few days time assuming they don't get predated. A search for a Willow Tits nest proved fruitless, not that they nest in hawthorns, brambles or nettles, but to access suitable dead wood I had to battle my way through some nettles and thorny thickets.

The best was saved for last when I checked out a new ringing site late in the afternoon. This site is a small overgrown field in a prime agricultural area and belongs to a relative. I was mainly checking it out as a winter feeding site for finches and buntings but quickly noticed the potential for breeding birds. There were 4 pairs of Whitethroats for starters but I was soon absorbed by a pair of Yellowhammers which were carrying food. They were clearly not used to seeing anyone in the field so I had to squat down in the vegetation and watch them from a good 75 metres away before they would ignore my presence.

I watched them carrying food back to the potential nest site for around an hour before I managed to narrow down the location. At first I thought they may be feeding recently fledged young as I could here some begging calls of young birds in the vicinity but my patience paid off and I eventually pinpointed the area they were visiting and marked it as being near a dead S shaped stem.

Yellowhammer nest location. There or thereabouts from about 10 metres away.
That was the easy bit, while I knew what my marker looked like through binoculars from 75 metres away the hard part was walking towards the location without losing sight of it. A stem which looks a distinctive S shape from a distance looks anything but a few metres closer and from a slightly different angle, especially when it is amongst hundreds of other dead stems. My first attempt to walk to it failed so I had to go back and wait for the birds to go in again and select a new marker. Both birds dropped into the same spot and this time I marked the location with different stems that I hoped to be able to keep better track of when I approached.

When I went in the second time I was able to keep sight of these markers and found the nest straight away. It was well concealed under some bramble trailers and amongst some willow herb. The nest contained 3 young that were about 7 or 8 days old and the ideal age for ringing.

Yellowhammer nest containing 3 young, The nest was quite a substantial structure made from coarse grass, other dead stems and lined with horse hair.

Yellowhammer nestling. The parents were mainly bringing green caterpillars to feed the hungry chicks. One of the nestlings was slightly smaller than the other two so the parents may have been struggling to find enough food for all three. Unfortunately the weed free fields and reduced headlands of modern agriculture provide much less in the way of caterpillars and other insect food for many of our once common farmland birds.

Yellowhammer nestlings about to be returned to the nest. The rings have been blackened with a marker pen so they don't stand out in the nest and get noticed by the parent birds.
After ringing the nestlings I made sure the nest was as concealed as when I found it and I also carefully covered my tracks as I walked away. I will return in about a week and just watch from a distance to check on progress. The young should be ready to fledge by then or may have just started to wander a little way from the nest as Buntings often leave before they can fly.

Hopefully I will suffer quite a bit of 'nesters arm' over the coming weeks now that the breeding season is getting into full swing.

Monday, 12 May 2014

Mystery Grasshopper Warbler remains so.

The unusual pale olive-grey Grasshopper Warbler caught on 25/04/14 (previous post can be found here) remains just that an unusual pale olive-grey Grasshopper Warbler. Much trawling of the internet and searching through various reference works and publications hasn't really thrown much light on the matter. I now know a lot more about Grasshopper Warblers but not much more about this particular bird. It still seems to be a potential toss-up between eastern sub-species and plumage aberration or rare colour morph. Whatever it is I haven't come across a comparable photograph including those of the eastern sub-species, straminea. However, some illustrations of straminea show spring birds can be greyish but seemingly not quite as pale as this particular bird.

Below are a couple of images of more typical olive-brown Grasshopper Warblers that were caught in the following days.

To try and progress matters I emailed Martin Garner to see if he had come across anything similar or to see if he could suggest any lines of enquiry. He agreed it was an interesting bird and requested some images for the Birding Frontiers website (link here) which focuses on identification issues and has a much better reach than my blog. Hopefully having some images published on that site may spark some suggestions but we still have to accept that we may never really know what it is in the absence of DNA testing. Whatever the outcome I still plan to submit it informally to the British Birds Rarities Committee (BBRC) for their consideration and for reference. If a bird like this can turn up once then it can turn up again.

One of the things I came across when researching via the net was a paper (link here) reviewing claims of Eastern Grasshopper Warblers in Britain (Harvey & Small 2007). This paper reported that the 4th primary was slightly emarginated in just over 50% of a sample of 20 of the eastern subspecies straminea and that this feather wasn't emarginated in any of the 12 nominate birds (naevia) examined. However one of the nominate birds I caught on the same day as the pale bird showed a slight emargination on the 4th primary. 

I had only photographed this bird's wing because it had clearly gone through some kind of eccentric moult and had replaced a number of primaries in both wings. These new feathers also stood out as they appeared longer than they should be relative to the old feathers either side. I only noticed the slight emargination of the 4th primary when comparing photographs of various Grasshopper Warblers subsequently. Although the emargination on the 4th is only slight it is clearly there, especially when the feather is compared with the 5th, and would be recorded as such for the wing formula of this bird. The presence of a slight emargination of the 4th primary may not be the potential indicator of a bird worth further examination as that paper suggests and perhaps more importantly shows how much we still have to learn about Grasshopper Warblers.

Sunday, 11 May 2014

Early May catch-up

Frequent heavy and blustery showers over much of the last week have really put a dampener on ringing activities. We had been spoiled by the weather for much of April so this unsettled period has drastically reduced the amount of time spent in the field and just when nesting activity was really taking off. It probably isn't doing nesting birds any good either as some of the downpours have been really heavy and wind gusts have approached near gale force at times; not good if you are a ground nesting Willow Warbler or a Reed Warbler trying to build a suspended nest in swaying reeds.

We had started to ring a few broods from some of the earlier nesting passerines before the weather changed. Robins topped the nestling ringing totals with 27 ringed from 6 nests followed by 2 broods each of Blackbird and Song Thrush. Quite a few other nests were in the pipeline largely thanks to Wayne's nest finding ability but it will be a case of finding a suitable weather window to follow-up on these until the weather picks up again.

Brood of Robins that have just been ringed and are about to be returned to the nest.

Song Thrush nestlings in the distinctive mud lined nest.

This Blackbird nest was on the root-ball of a small fallen tree.

Only 2 Blackbird chicks in this nest but they all count.

This weather has also affected catches in the moth trap. Catches were fairly low at the end of April but have fallen further with low single figure counts being the norm so far this month. However a few firsts for the year are turning up just now and again to keep a bit of interest going and a White-pinion Spotted on the morning of the 7th being a good example. This morning the catch was particularly dire with only a rather worn Clouded Drab, similarly worn Common Quaker, a Shuttle Shaped Dart and a slug in the trap. It goes to show how wet it has been when slugs are seeking shelter.

This White-pinion Spotted didn't quite find its way into the trap and was found resting on
the wall nearby. This is a species that has become a bit more common in recent years
but it is still a fairly scarce visitor to the garden.
Male Muslin Moths have put in an appearance on 3 days so far this month.

Leopard Slug in the moth trap this morning.
These can grow really quite big so this is a relative youngster.
The weather is looking better from mid-week so hopefully we can catch up with some nest recording and ringing from then.