Thursday, May 14, 2009

Geriatric Great Tits

Great tits live long enough in the wild to suffer the burden of old age. As the years pile up, the birds become less able to raise healthy chicks and produce fewer young.
The findings,
recently published in the Proceedings of the Royal Society B, come as a surprise because it was thought that wild birds die well before the onset of ageing.
The most important finding is that female great tits living beyond 2 years of age show reduced offspring production. This means that at any time 1 in every 5 breeding females is affected by ageing.
Generally studies of this nature only collect data on first egg dates, clutch sizes, hatching dates and fledging rates – but make no attempt to relate that back to the age of the maternal parent. This report is unique to that extent.
And to paternal parents: 14 percent of chicks are not fathered by the male who raises them, so age-specific parentage is not accurate.

http://planetearth.nerc.ac.uk/news/story.aspx?id=420

A dilemma


Within farming a switch is occurring whereby previous grass silage is being replaced by maize silage. A bonus is that maize needs less nitrogen (fits with Nitrate Vulnerable Zones Policy), has greater productivity and lower production costs. The switch to maize is, to an extent, being driven by the need to grow crops with less nitrogen use but also because climate change makes it possible.

On the other hand, compared to grass silage, soil erosion is greater under maize, and oxidation of soil organic matter becomes a source of atmospheric carbon – rather than a carbon sink which grassland is.

So it’s dammed if you do, and dammed if you don’t.

Thursday, May 07, 2009

Ethogram (I didn't know either)

An ethogram is a catalogue of discrete behaviors typically employed by a species. Still non the wiser!
When collecting data on species it is usually undertaken by monitoring individuals. This is all well and good if the species inhabits areas easy to access permitting them to be followed easily. When, however, they move quickly, inhabit areas without access, or have behaviours that result in changes of altitude, or depth, it becomes more difficult.
Technology is improving and remote data loggers attached to animals are making it easier. In one such study (see: http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0005379) they have used accelerometers to record behaviour. These types of loggers are particularly useful in that they can record the dynamic motion of a body in e.g. flight, walking, or swimming.
Using the shag, Phalacrocorax aristotelis, as a study species, they have been able to record the behaviour of a bird by analysing the resultant 'surge' profiles. They can determine when it was swimming, walking or flying, and when it was diving (including the duration of the ascent and descent, and even the depth that it dived too) .
This is exciting news - it now permits the remote monitoring of species previously impossible. My only reservation about all of this is that you have to have some knowledge of the behaviour of the species in order to make any meaningful interpretation of the surge profile. In the case of little know species this could be difficult.

World Migration Day and 100 years of ringing

On the 8th May we celebrate 100 years of bird ringing in the UK. On the 9-10th May we celebrate World Migratory Bird Day. Over the next few weeks an estimated 16 million birds will arrive in the UK, after spending the winter as far away as South Africa. Bird watchers in general, twitchers in particular, and ringers (as usual) will be out and about watching, recording and, in the case of the latter group, catching, measuring and ringing, as many birds as they can.
Our love of birds is a two edged sword. On the one hand we have the desire, knowledge and know-how to identify species by sight and sound and to revel in our ability to do so. On the other our recording and survey work reveals the slightest dip (and increase) in any species, often indicating a habitat, and world, in turmoil.
We think we know a lot but, the more you know the quicker you realise how little you really know. It is important to keep recording, surveying, watching and ringing to help others, more knowledgeable than ourselves, detail what is going wrong with the world so we can attempt, if we wish, to put it back into a more harmonious balance.

See: http://www.borntotravelcampaign.com/

Lapwing WAS number 1

On the 8th May 1909 the first bird ever, a Lapwing, was ringed in Aberdeen. Since then over 36 million different birds, using 11.3 tonnes of metal, have been ringed. Ironically, or maybe predictably, the first bird recovered abroad was also a Lapwing - ringed in Scotland and found in France.
Ringed birds have turned up in many different ways: they’ve been eaten by crocodiles in Gambia (Osprey), by Chimpanzees in zoos (Buzzard), caught by African spiders (Reed Warbler), hit whaling ships in snowstorms (Arctic Tern), been hit by golf balls (gulls and ducks) and even died after getting their bill stuck in the hem of a blanket (Barn Owl)!
Although so many birds have been ringed there is still a lot to learn. Whilst we now know a lot about the movements of Swallows (the first recovery was in South Africa in December 1912), we know next to nothing about their close relative the House Martin, with just two birds found south of the Sahara (in Senegal and Nigeria). Similarly, the wintering areas of Spotted Flycatchers and Pied Flycatchers remain a mystery. Given that both of these last two birds are declining rapidly it is becoming imperative that we fill these gaps in our knowledge.
Ringing also tells us a great deal about survival rates of our birds. Our oldest ringed bird, at 50 years and 11 months, is a Manx Shearwater; originally ringed at Bardsey Bird Observatory, North Wales, on 17 May 1957, it has bred on the island each summer ever since.

BTO volunteers ring over 800,000 birds every year. Part of the BTO Ringing Scheme is funded by a partnership of the BTO and the Joint Nature Conservation Committee (on behalf of Natural England, Scottish Natural Heritage and the Countryside Council for Wales, and also on behalf of the Northern Ireland Environment Agency). The scheme also receives support from National Parks and Wildlife (Ireland). The volunteer ringers give freely of their time and expertise and also provide a substantial part of the Scheme’s funding.

See: http://www.bto.org/ringing/ for more information.

Monday, May 04, 2009

...the Mistle Thrush.

Found this nest quite by accident. Where I can, I scan nest boxes with binoculars in order to see if there is any activity before approaching the box. I was looking at a box about 30 yards away when something didn't appear quite right. About 25feet above the box was an unusual white patch. On examining further it was a Mistle Thrush, frozen, looking at me looking at it!

My route took me away from this box initially but, when I did get there in order to check the box below, the Mistle Thrush was 'away'.

A quick off-loading of kit and a climb up the tree revealed the nest - five young, big by usual passerine standards, but blind and downy by thrush criteria. A quick photo and exit should, hopefully, find me ringing the pulli next weekend.

Nest box season begins

Checked all the nest boxes this weekend – bar one, which went awol! Had eight Great Tits all sitting, so couldn’t check contents but all must be sat on full clutches, and one Blue Tit doing the same. Then had another eight ‘tit’ nests with eggs 1x3, 1x4, 3x6, 1x8 and 2x9. At least one of these I think is Coal Tit, three Blue Tit and the rest Great Tit. Another 20 possible nests were under construction.

For Pied Flycatchers have three nests with eggs (1x1, 1x2 and 1x3) with another fourteen nests under manufacture. At the moment it is impossible to tell whether any of these will be due to Redstarts.

Other findings included a Mistle Thrush nest with five blind and downy young, another nest with parents feeding – but high up a rotting alder tree, so wasn’t about to climb that and a Tree Creeper nest which I’ll have to check again next week (when I have a torch!). Also discovered two pairs of Nuthatches feeding young and Blackbirds and Song Thrush carrying food – but with insufficient time to track back to nests. A few Chiffchaff alarm called as I passed by but Willow Warblers and Blackcaps were still singing. Ravens and Buzzards were quiet and the cuckoos only appeared late on it the day.