Migratory flyways: The perils facing birds

We are aware that Curlews are as rare as hen’s teeth (if not rarer) in the Cotswolds. For an insight of the multiple threats faced by migratory water birds you might be interested in a BBC World Service/ABC 4 part series on the East Asian Australasian Flyway which covers 22 countries. Although it focuses on an area far to the east of us, the lessons are applicable here – particularly when it comes to development and the argument* that you hear that the birds will move somewhere else if their feeding grounds are ‘developed’. They don’t.

But you can try to mitigate the effects as you will hear in part 1.

I haven’t listened to part 2 yet, but as it features South Korea I think I am going to be even more depressed. It reduced ecologist Richard Fuller to tears as you will hear.

Part 1 is here

Part 2 here

Parts 3 and 4 haven’t been broadcast yet, but the home page where all the episodes will be available is here.

It just underlines the fact that what we think of as ‘our’ birds have lives outside of the UK and there are multiple threats

*advanced, for example when Cardiff Bay was developed and as a defence for the disruption that would be caused by the Severn Barrage

Farmland Bird Monitoring 2

2016 ringing photos

I completed my last ringing session of the winter in April. Despite the excessively wet and windy conditions over the winter period, I managed six mist-netting sessions at Woeful Lake Farm and a further session at Stones Farm. The site at Woeful Lake Farm consists of arable fields with a large area of cover crop and mature hedgerows. The site at Stones Farm is an old quarry surrounded by arable fields with grassy field margins and mature hedgerows. The quarry has a sheltered grassy area surrounded by scrubby bushes and trees. Both sites have been fed with seed throughout the winter. The site at Stones Farm has very good numbers of Yellowhammer, Linnet and Reed Bunting and looks to be a promising addition to the project next winter.

The table below summarises the birds caught for the first time and those recaptured throughout the winter period.

Species New birds Recaptures
Wren 1
Great Spotted Woodpecker 1
Dunnock 15 3
Robin 5 2
Blackbird 3
Goldcrest 3
Long-tailed Tit 2
Coal Tit 1
Blue Tit 48 21
Great Tit 14 1
Chaffinch 17
Greenfinch 12 1
Goldfinch 2
Linnet 13
Yellowhammer 8
Reed Bunting 1

The numbers of Linnet and Yellowhammer caught increased towards the end of the winter. This is because natural food supplies diminish as winter progresses and birds gather at areas where food remains – in this case where we provided supplementary seed. The relatively warm winter this year may have reduced the size of winter flocks – although there was a flock of up to 80 Linnet using the site this year, this is considerably smaller than the flock of several hundred present in previous years.

Examination in the hand revealed that the Yellowhammers and Linnets caught were a relatively even mixture of adult birds and first year birds (i.e. birds born in the 2015 breeding season). Previous studies and ringing recoveries have shown Yellowhammers in particular to be sedentary, with similar breeding and winter distributions and few long distances movements of birds. The capture of first year birds therefore indicates that Yellowhammers have bred successfully in the area last year and in the future it should be possible to look at changes in the proportion of adults to first year birds as an indicator of changes in breeding success.

To date I have only had one recovery of a ringed bird by a third party. A Great Tit ringed in December was recaptured by another bird ringer in Sibford Ferris (Oxfordshire) on 31 March 2016, a movement of 31km. It is unusual for a Great Tit to move as far as this but first year birds, such as this one, are known to be more likely to disperse than adults.

A more detailed report of the project so far can be found in the NCOS newsletter, and please continue to look out for colour ringed Corn Bunting (yellow with black characters) and Yellowhammer (dark blue with white characters) on the Sherborne Park Estate.

Red Listed

Turtle Dove Richard Tyler

Turtle Dove                                                                          Richard Tyler

This Saturday (16th April) sees the African Bird Club AGM at the Natural History Museum in London.  There are half-a-dozen associated talks, and the event is open to members and non-members alike.

Of particular interest to us here in the Cotswolds is a talk on Turtle Doves in their wintering grounds in Senegal by Niki Williamson. Fewer and fewer of these birds visit the UK in summer.  They are now scarcely seen in Gloucestershire and no longer breed in the county at all.

Curlew Richard Tyler

Curlew                                                                                         Richard Tyler

And closer to home, don’t forget our own AGM this Weds (13th April) at the Farmers Arms, Guiting Power at 7:30.  Our guest speaker is Mike Smart, the county’s previous BTO rep, on ‘The Decline of the Curlew’  – very topical with members of the Society involved in the RSPB Curlew survey at the moment.

Farmland Bird Monitoring

Last autumn, NCOS kindly provided me with a grant to help set up a farmland bird ringing project on the National Trust’s Sherborne Park Estate. The Estate has good numbers of farmland birds present in both the breeding season and over-winter, including red-listed species such as Corn Bunting Emberiza calandra, Yellowhammer Emberiza citronella, Linnet Carduelis cannabina and Skylark Alauda arvensis. The project’s aim is to increase understanding of population changes and local movements of farmland bird species over the medium term to help us make conservation management plans for the Estate. I hope to achieve this by a combination of regular winter ringing sessions and nest monitoring in the breeding season.

Yellowhammer

Ringing birds is very weather dependant as mist nets cannot be used in windy or wet conditions and so there have been limited opportunities to get out so far this winter. However, I have fed the site since October and managed a number of short sessions, which have proved useful to observe bird behaviour and optimise catching methods. A flock of up to 100 Linnet has been building, and good numbers of Chaffinch Fringilla coelebs with smaller numbers of Greenfinch Chloris chloris, Goldfinch Carduelis carduelisi, Reed Bunting Emberiza schoeniclus and Yellowhammer have also been present, and I have so far ringed a number of these species as well as commoner generalist species. As winter progresses and natural food supplies diminish, I hope numbers will build further.

To maximise the data obtained by the project I will be colour-ringing any Corn Bunting and Yellowhammer caught, as both species perch prominently in the breeding season and so should be easy to re-sight. If any NCOS members are out walking on the Sherborne Park Estate, please check these species for colour rings and report them to CotswoldsCR@outlook.com. Corn Bunting colour rings are placed on the left leg and are yellow with one letter and two numbers engraved in black. Yellowhammer colour rings are also placed on the left leg and are dark blue with two letters engraved in white.

Barn Owls – Part 2

Barn Owls at six-and-a-half weeks

Barn Owls at six-and-a-half weeks

On last month’s expedition to ring a brood of Barn Owls we found another barn containing a nest-box that no-one had been aware of. Closer inspection revealed three newly-hatched chicks. As they were reckoned to be about one, three and five days old, they were too young to be ringed that day.

We came back nearly six weeks later and found an adult (which immediately slipped away) and two well-grown chicks. Don’t ask what had happened to the third…

A. ringing the elder one.

A. ringing the elder one

D. did the retrieving

D. retrieving the chicks in cotton bags

Weights...

Weights…

...and measures

…and measures

 

 

These chicks were slightly less advanced than the other brood when we ringed them – see how much down they still have compared to these.

M. who was supervising (Barn Owl ringing needs a Schedule 1 endorsement to the ringing permit) looked up the wing measurements in the tables, and pronounced the birds to be between 44 and 46 days old. This agrees very well the estimate of one to five days old when we first found the brood. It also suggests, unsurprisingly, that it was the youngest sibling that did not survive.

Barn Owls

Young Barn Owls Tom Beasley Suffolk

Young Barn Owls                                                         Tom Beasley Suffolk

After 2014’s massive year for Barn Owl breeding, 2015 has been miserable. M reckons he has inspected 40 boxes in the whole county this year and ringed one single chick!

A retrieving the chicks

A retrieving the chicks

 

Better news, though. A box near Sherborne contained a very young chick and three eggs at the beginning of July.

Several weeks later there were three well-grown young, just past the ‘ugly’ stage and shedding their juvenile down whenever they moved.

Measuring to estimate the age

Measuring to estimate the age

 

 

 

 

All three were ringed and measured. Incredibly (to me at least) you can age the chicks pretty accurately by measuring the seventh primary feather’s length and looking it up in guru Colin Shawyer‘s tables.

M weighing a chick in the bag

M weighing a chick in the bag

 

 

 

Weighing was also a surprise – the older the chick, the lighter they are.
They reach their maximum weight in the nest and slim down to flying
weight as they develop.

New Groups

Barn Owl       -  rob Brookes, from 'Birds of the Cotswolds' (Liverpool University Press 2009)

Barn Owl – Rob Brookes, from ‘Birds of the Cotswolds’ (Liverpool University Press 2009)

Two new bird study groups have been set up within the county recently. The first is the Gloucestershire Barn Owl Monitoring Programme, which seeks to provide advice and support for Barn Owl conservation. This project will liaise primarily with landowners and farmers, as Barn Owls have become so dependent on nest-boxes and the land on which they are sited. Sightings are crucial, though – if you don’t know where the owls are, you can’t put up nest-boxes or ring the birds.

The other group is the Gloucestershire Raptor Monitoring Group. This group will study a mixture of raptor species (suggestions welcome) and may also include Ravens, whose lifestyle and survey methods have similarities with raptors, and other owls. These species are far less popular with landowners – for understandable reasons – and the emphasis will be on birders logging sightings, breeding activity and behaviour.

The Gloucestershire Raptor Monitoring Group held its first meeting last Saturday at St Peter’s High School, Gloucester (a big thank-you for providing the facilities for free!). There were over 50 people there of all levels of skill and experience, but united in enthusiasm. The species picked out for further study at the moment are: Peregrine, helped by a very entertaining account of those at Symonds Yat by Steve Watson; Kestrel, whose numbers here have perked up this summer (but for how long?); Red Kite, which have now bred in the county for the first time in 150 years; and Goshawk, a fair number of which have been ringed due to Rob Husbands’ climbing ability and Schedule 1 licence.

Pics:   Mervyn Greening

Pics: Mervyn Greening

Picture:  Mervyn Greening

A Bill Guided by an Eye

Oystercatcher and young

Oystercatcher and young                                                  –   Richard Tyler

A fascinating talk at the Cheltenham Bird Club by Graham Martin, whose speciality is bird vision. Having given us the elegant idea that “a bird is a wing guided by an eye“, he then proceeded to argue against it.

He suggested that the evolution of birds’ eyes is not driven by the long-distance vision required by flying, but by the requirements of close-up work, specifically that of feeding. If you can’t fly accurately, you can usually get away with a clumsy landing; but if you can’t peck accurately or grab from your parent’s bill, you starve quite rapidly. The vast array of different bill-shapes is complemented by a wide variation in birds’ visual capability (although this is much less obvious) which allows each species to use its particular bill to good effect.

Graham’s work on birds’ eyes and blind spots has practical implications for collisions with man-made structures like pylons and wind turbines. Some birds have evolved to scan the ground while flying, and so their blind spots – the top of the head and the back of the neck – face the way they’re moving. This can be dangerous today, but then there hasn’t often been anything in their line of flight until the last fifty years.

Nest Recording

An excellent talk from Ed Drewitt on Urban Peregrines last night at our AGM. Also a chance to meet various Forest of Dean volunteers from the RSPB’s Peregrine site at Symond’s Yat – thanks for making the long trip, and all crammed into a single car!

095_PE_P_1597

You looking at my nest? You’ll need a Schedule 1 licence                                          Photo: Dave Pearce

Our own (‘our own’…!) urban Peregrines in Cheltenham are progressing well this year with four eggs laid in early April. We will be watching closely for developments in the nest over the next few weeks, and putting video clips on this website.

Recording what happens in nests gives a whole new view of birds that you don’t get from simply spotting them. Date of laying, clutch size and nestling survival rates give an insight into a bird’s breeding biology, and also shed light on the environment around it.

It’s even better if you happen to have a huge database stretching back many years to compare with. The British Trust for Ornithology’s Nest Recording Scheme is 75 years old this year (NCOS has been contributing to it as a group for 10 years). As well as looking at how different species are doing at present, it means the team is able to look back and chart timelines. UK Peregrines, for instance, declined through the 1950s and 1960s: they laid the same number of eggs as before, but fewer hatched. This led to the examination of the nests and eggs, and the discovery of thinner eggshells, and then to the link with pesticides in eggshells. They recovered later (same number of eggs but more hatched) and started moving into urban areas around the millenium.

Anyone can record nests, whether in the countryside or in your back garden nestbox, and this is the time of year to get involved. Check out NRS News: this is the 2013 breeding season – why not contribute to the 2014 version?

Looking for birds? Find a Nightjar

As we all know, finding birds in August can be a bit of a challenge. So here’s another: try your skills at finding cryptic species and help researchers studying camouflage. Scientists at Exeter are using computer games to look at animal perception as part of a wider programme looking camouflage and how species avoid predation. Play Where is that Nightjar and join in. My best score was 1.2 seconds, but for one the game timed out!

Have fun!