Wednesday, November 29, 2017

Speciation in Forty Years

There’s fascinating and exciting stuff for students of evolution and migration from Science Daily of 23rd November 2017. 

 “A study of Darwin's finches that live on the Galapagos Islands in the Pacific Ocean, has revealed direct genetic evidence that new species can arise in just two generations. 

The arrival 36 years ago of a strange bird to a remote island in the Galapagos archipelago has provided direct genetic evidence of a novel way in which new species arise. Researchers from Princeton University and Uppsala University in Sweden report that the newcomer belonging to one species mated with a member of another species resident on the island, giving rise to a new species that today consists of roughly 30 individuals. 

The study comes from work conducted on Darwin's finches, which live on the Galapagos Islands in the Pacific Ocean. The remote location has enabled researchers to study the evolution of biodiversity due to natural selection. 

The direct observation of the origin of this new species occurred during field work carried out over the last four decades by B. Rosemary and Peter Grant, two scientists from Princeton, on the small island of Daphne Major. 

"The novelty of this study is that we can follow the emergence of new species in the wild," said B. Rosemary Grant, a senior research biologist, emeritus, and a senior biologist in the Department of Ecology and Evolutionary Biology. "Through our work on Daphne Major, we were able to observe the pairing up of two birds from different species and then follow what happened to see how speciation occurred."

In 1981, a graduate student working with the Grants on Daphne Major noticed the newcomer, a male that sang an unusual song and was much larger in body and beak size than the three resident species of birds on the island.


"We didn't see him fly in from over the sea, but we noticed him shortly after he arrived. He was so different from the other birds that we knew he did not hatch from an egg on Daphne Major," said Peter Grant, the Class of 1877 Professor of Zoology, Emeritus, and a professor of ecology and evolutionary biology, emeritus.

The researchers took a blood sample and released the bird, which later bred with a resident Medium Ground Finch of the species Geospiz fortis, initiating a new lineage. The Grants and their research team followed the new "Big Bird lineage" for six generations, taking blood samples for use in genetic analysis.

In the current study, researchers from Uppsala University analysed DNA collected from the parent birds and their offspring over the years. The investigators discovered that the original male parent was a Large Cactus Finch Geospiza conirostris from Española island, which is more than 100 kilometers (about 62 miles) to the southeast in the archipelago.

Large Cactus Finch Geospiza conirostris - Harvey Barrison from CC BY-SA 2.0 via Wikimedia Commons 

Medium Ground Finch Geospiz fortis - Charles J Sharp - CC BY-SA 3.0 via Wikimedia Commons

The remarkable distance meant that the male finch was not able to return home to mate with a member of his own species and so chose a mate from among the three species already on Daphne Major. This reproductive isolation is considered a critical step in the development of a new species when two separate species interbreed. The offspring were also reproductively isolated because their song, which is used to attract mates, was unusual and failed to attract females from the resident species.

The offspring also differed from the resident species in beak size and shape, which is a major cue for mate choice. As a result, the offspring mated with members of their own lineage, strengthening the development of the new species.

Researchers previously assumed that the formation of a new species takes a very long time, but in the Big Bird lineage it happened in just two generations, according to observations made by the Grants in the field in combination with the genetic studies.

All 18 species of Darwin's finches derived from a single ancestral species that colonized the Galápagos about one to two million years ago. The finches have since diversified into different species, and changes in beak shape and size have allowed different species to utilize different food sources on the Galápagos. A critical requirement for speciation to occur through hybridization of two distinct species is that the new lineage must be ecologically competitive -- that is, good at competing for food and other resources with the other species -- and this has been the case for the Big Bird lineage.

"It is very striking that when we compare the size and shape of the Big Bird beaks with the beak morphologies of the other three species inhabiting Daphne Major, the Big Birds occupy their own niche in the beak morphology space," said Sangeet Lamichhaney, a postdoctoral fellow at Harvard University and the first author on the study." Thus, the combination of gene variants contributed from the two interbreeding species in combination with natural selection led to the evolution of a beak morphology that was competitive and unique."

The definition of a species has traditionally included the inability to produce fully fertile progeny from interbreeding species, as is the case for the horse and the donkey, for example. However, in recent years it has become clear that some closely related species, which normally avoid breeding with each other, do indeed produce offspring that can pass genes to subsequent generations. The authors of the study have previously reported that there has been a considerable amount of gene flow among species of Darwin's finches over the last several thousands of years.

One of the most striking aspects of this study is that hybridization between two distinct species led to the development of a new lineage that after only two generations behaved as any other species of Darwin's finches, explained Leif Andersson, a professor at Uppsala University who is also affiliated with the Swedish University of Agricultural Sciences and Texas A&M University. "A naturalist who came to Daphne Major without knowing that this lineage arose very recently would have recognized this lineage as one of the four species on the island. This clearly demonstrates the value of long-running field studies," he said.

It is likely that new lineages like the Big Birds have originated many times during the evolution of Darwin's finches, according to the authors. The majority of these lineages have gone extinct but some may have led to the evolution of contemporary species. "We have no indication about the long-term survival of the Big Bird lineage, but it has the potential to become a success, and it provides a beautiful example of one way in which speciation occurs," said Andersson. "Charles Darwin would have been excited to read this paper." 

Sangeet Lamichhaney, Fan Han, Matthew T. Webster, Leif Andersson, B. Rosemary Grant, Peter R. Grant. Rapid hybrid speciation in Darwin’s finches. Science, 2017; eaao4593 DOI: 10.1126/science.aao4593



Sunday, November 26, 2017

Down And Down

No apologies today for returning to a recurrent theme of Another Bird Blog. From a recent article in The Guardian newspaper.

The latest official figures show that birds on the UK’s farmland have seen numbers decline by almost a tenth in five years. Farmland bird populations have declined by 56% since 1970, largely due to agricultural changes including the loss of mixed farming, a switch to autumn sowing of crops, a reduction in hay meadows and the stripping out of hedgerows. 

While the majority of the decline happened during the late 1970s and 1980s as farming practices changed rapidly, there was a 9% decline between 2010 and 2015, the statistics from the Department for Environment, Food and Rural Affairs (Defra) show. 

The latest figures have prompted renewed calls for an overhaul of farming as the UK leaves the EU and its system of agricultural subsidies, to support wildlife and farming. The data showed some “specialist” species, those restricted to or highly dependent on farmland habitats, have seen precipitous falls - Corn Buntings, Grey Partridge, Turtle Doves and Tree Sparrows have all suffered declines of more than 90% since 1970, though others such as Stock Doves and Goldfinches saw populations double. 

For Turtle Doves in particular, dramatic falls continue, with numbers down 71% between 2010 and 2015. 

Corn Bunting

Grey Partridge

For those of us out in the countryside on a regular basis these figures are no surprise, just a confirmation of that we know to be true. 

Elsewhere in the countryside, woodland birds have seen numbers remain relatively stable over the last five years, although they are down almost a quarter (23%) since 1970. Across all species, including farmland, woodland, wetland, waterbirds and seabirds, numbers are down around 8% on 1970 the figures show. 

The RSPB’s head of land use policy, Jenna Hegarty, said: “Birdsong from some of our most iconic species once filled the air, but for many years the soundtrack of our countryside – from the song of the Skylark to the purr of the Turtle Dove – has become quieter and quieter. 

Turtle Dove
 
 Skylark

“Today’s figures show the number of farmland birds continues to drop. The farmland bird indicator has fallen by 9% in the last five years – the worst period of decline since the late 1980s. Many farmers are doing great things, and without their efforts, today’s figures would undoubtedly be worse. But the current agriculture system doesn’t work for our farmers or our natural environment, something needs to change."

“Leaving the EU gives us a seminal opportunity to overhaul the system, and use public money to build a more sustainable future, reversing the dramatic declines in farmland wildlife and supporting resilient and thriving farm businesses into the future.” 

Hear, hear.

Linking today to Stewart's World Bird Wednesday




Friday, November 24, 2017

After The Deluge

We’ve had a lot of rain. On Thursday we had a month’s average rainfall in less than a day. Fifteen miles from here the River Conder burst its banks just south of Lancaster and flooded the village of Galgate. The story made the national TV news. 

When I set off birding this morning I ran into still partially flooded roads that criss-crossed acres of waterlogged fields. Three miles south of Lancaster and on the other side of the River Lune the fields surrounding Cockersands Abbey (circa 1184) were some of the worst. That’s the tiny ancient abbey in the centre of the picture with Mute Swans installed on the flood. 

Slack Lane, Cockersands

B&W of Slack Lane


 Cockersands Abbey

As might be expected the floods held lots of birds looking for food washed from the ditches, dykes and already saturated ground following historic summer rain. Too many to count and scattered far and wide were Starlings, Lapwings, Golden Plovers, Curlews, Redshanks, Mallards, and a couple of Grey Herons. 

A stop and look found 40 Meadow Pipit, 14 Goldfinch, 8 Tree Sparrow, 4 Greenfinch, 3 Chaffinch, 3 Pied Wagtail, 2 Reed Bunting and 2 Skylark. The Golden Plovers spooked at nothing and then wheeled around, twisting and turning in unison before they settled again among Lapwings, Redshanks and paddling Starlings. The morning sun lit up the plovers' pale bellies against the shower filled sky.

Curlew

Meadow Pipit

Meadow Pipit

Grey Heron

Golden Plover

The herd of Whooper Swans picked a well-drained field in which to spend their days. They are more scattered across the field but still in excess of 400 individuals and ever wary to passing cars that slow or stop for photographs. The now well-trodden field grows muddier by the day but the swans’ method of feeding leaves them looking less than white. 

Whooper Swans
 
After the Deluge

I called at our Linnet field, waded along the net ride and dropped seed into the nearby vegetation. With a little luck the 140+ Linnets will stay around and we’ll get a ringing session when it stops raining and our seed stops washing into the adjacent ditch. 

Linnet

Back home I was greeted by a calling Nuthatch, one of the few birds in the garden just lately. 

Nuthatch

Even the Goldfinches have mostly deserted us after weeks and weeks of cascading water.

Linking today to Anni's Birding Blog  and Eileen's Saturday Blog.



Sunday, November 19, 2017

Stone Me

Next week’s weather looked dire. Sunday might be the only opportunity to get some ringing done. So with a promised 3mph I drove up to Gulf Lane and an early start. 

No Andy today. And he had the single panel nets in his car except for a brand new Ecotone that languished in my boot. I put up the one net but it was shiny and pristine, straight out of the packet from Poland and by now the rising sun lit up the mesh. Mist nets are better when the new shine has worn off and they take on a greyer tone that merges into backdrop of the customary British weather. 

Anyway that’s my excuse for catching just 4 Linnets in a couple of hours. And I think the number of Linnets around at 180-200 suggests that this consistent count of recent weeks holds regular birds and few newcomers. 

But that miserly four equates to 251 new Linnets for the year of which 194 are from this autumn/ winter. And still not a single recapture. 

The Linnet below is a rather smart adult female. 

Linnet

All was not lost as I caught a Stonechat, almost certainly the quite distinctive male resident here for the last couple of weeks. I racked my brains to think of the last time I ringed a Stonechat in Lancashire so looked it up on the database - 1993. That timescale is indicative of both the species’ scarcity around here and also its liking for open habitats where ringers are not terribly active. 

The Stonechat “took the Micky” for a while and at one point perched up on one of the 4ft high bamboos that held the net and from where it could certainly see the mesh stretching to the other end. Ten minutes later it was lying in the net alongside a Linnet. 

In this part of coastal Lancashire the Stonechat is a scarce, partially migrant breeding bird, mainly on the edge of the Bowland hills but occasionally along the coastal strip. In many a spring it is a slightly more numerous and early passage migrant during February to April. Likewise, a migrant in autumn when odd birds may linger into December and beyond or even spend the winter if the weather stays mild enough. 

After 25 years I needed to consult “Svensson” to if possible age this obvious male. Through a combination of factors, bill, alula, tail wear and shape, plus the amount of black on the head, mantle and throat, I considered it an adult. 

"Svensson"

Stonechat in Svensson

Stonechat

Stonechat

Lots of other birds around this morning, mainly in flight by way of many hundreds of field-grazing Lapwing, Golden Plover and Curlew. Others – Sparrowhawk, Whooper Swans and Little Egrets.

Linking today to Stewart's World Bird Wednesday.


Friday, November 17, 2017

Mix And Match

Today’s forecast was a little over the top windy for ringing at our exposed sites so I indulged in a few hours birding, camera at the ready. It turned out to be a day of mixed fortunes with both sunny and cloudy periods, showers, and even a spot or two of sunshine. At the end, a few photos to share. 

The drive across Stalmine Moss found three Kestrels, a hunting pair and then at the junction of Lancaster road a third one in flight. I slowed to scan the fields where a Barn Owl might be seen but none emerged from the post dawn light, just three chattering Fieldfares. The thrushes carried on south but I would see a number of others soon. 

I stopped at Gulf Lane to count the Linnets and drop food. Still 130+ Linnets, plus a number of Tree Sparrows at the farm 50 yards away. We don’t include the sparrows in our counts as they do not visit our seed even though it is a very short flight for them. I guess there must be lots of natural around at the moment and no need for them to sign in to our free food bank. 

Further around Gulf Lane were another 40 or so Tree Sparrows. They fed in a roadside stubble field and when spooked by a passing vehicle flew up to a handy tree or hedgerow until the danger passed. 

Tree Sparrow

Following this very wet summer and autumn herds of Whooper Swans, small and large, are scattered across many areas of Pilling, Cockerham, Cockersands and Eagland at the moment. There are so many swans that if on a morning flight the lot were to try and feed in one field they might struggle to do so; even more when both Whoopers and the many dozens of Mute Swans seem not to mind sharing their largesse of abandoned crops. 

So it was that out on Moss Edge I watched a herd of 20 Mutes and 30 Whoopers as they fed untroubled in yet another morass of mud and corn stubble. I even managed to single out a family group for a picture. What fine animals they are and aren’t we so very honoured to welcome them to our local landscape each winter? Two Little Egrets fed in the adjacent grass and looked slightly out of place, somewhat exotic in comparison to the Icelandic swans.
Whooper Swan

Whooper Swan

Little Egret

The hawthorn berry crop was poor this year. Following the October/November invasion of Fieldfares, Blackbirds and other thrushes this already low food resource is now almost gone. On Moss Edge the hawthorns are pretty much depleted and it was noticeable that a flock of approximately 130 Fieldfares searched both the ground and the hedgerows for something to eat. In normal years the hedgerows provide bird food for a few more weeks. 

Fieldfare

Fieldfare

I stopped at Conder Pool more out of habit than expectation. Old Faithful really struggles to provide any birds at the moment so I was not surprised with the regular counts of 190 Teal, 14 Wigeon and about 30 each of Lapwing, Redshank and Curlew. The customary 3 Little Grebe, 1 Goosander and 2 Little Egret. 

I found nothing of note on the circuit of Moss Lane/Jeremy Lane with none of the thrushes of late except for a Mistle Thrush into the light. 

Mistle Thrush
 
It was time for a coffee near the Lune. As luck would have it a flock of Linnets flew by and some landed on the nearby fence. Even better there was a single and perhaps one or two more Twite plus a curious Wren. 

Wren

Linnet

Twite

Linnet
 
Twite

The Twite Linaria flavirostris and the Linnet Linaria cannabina are similar in looks but are two separate and quite distinct species. The genus name Linaria is the Latin for a linen-weaver, from linum, "flax" and flavirostris means yellow-billed; cannabina comes from the Latin for hemp. 

The Linnet is a mostly farmland bird at all seasons of the year but one that can be found at higher elevation on moorland edge in the summer and autumn. In contrast the Twite sometimes known as “mountain linnet” favours treeless moorland for breeding and frequents lowland and mainly coastal haunts in winter only. It is in the winter when both species are more likely to seen using the same coastline areas in which to feed. 

Time passed quickly and my time was up. It had been a good morning with a rather nice mix of species.

Linking today to Anni's Birding Blog and Eileen's Saturday Blog.



Wednesday, November 15, 2017

More Linnets Please

Just yesterday I entered some recent counts of Linnets at Gulf Lane into the BTO’s Bird Track. The system flagged up that the counts were of an “unusually high number”. Well BTO it’s good to hear that, especially as discovering more about winter Linnets is the objective of our project here. 

BirdTrack - BTO

Throughout September and October spot counts here varied between 50 and 100 Linnets during a period of poor and mostly wet and windy weather. In the last week and into November and with more settled weather there have been nearer 200 birds at any one time. 

Wednesday 15th and at last a morning of less than 5 mph winds. I met Andy at 0715 and ten minutes later the single panel nets stood ready for the Linnets as they arrived from roosts ready for their first feed of the day. 

Parties arriving varied between 3 and 30 individuals until our best counts of the morning realised 135 Linnets at any one time, a reduction from the most recent count of 200 on 11th November. Past catches tend to equate to approximately 10% of the spot count, just as today with 13 caught. This brought our running total to 190 Linnets for this autumn period. 

Today’s catch comprised 1 adult male and 12 first winters, 4 female and 8 male. In addition we caught a single Wren. One of today’s Linnets came in at a healthy 85mm wing and 19 grams, another two at 84mm and 19.4 and 19 grams, leading us to again speculate that such individuals originate from Scotland. 

Linnet

More time, more captures and more recaptures of Linnets ringed elsewhere may help us to prove the theory. All we need is more ringers catching and ringing spring, summer, autumn and winter Linnets.  

For the benefit of ourselves, the farmer and his Higher Level Stewardship (HLS) scheme we record all bird species using the site on each and every visit. Today the list was restricted to Linnets, a Sparrowhawk and the aforementioned Wren. 

Fly overs today were Whooper Swan, Lapwing, Skylark, Kestrel, Buzzard, Meadow Pipit and Pink-footed Goose. Geese flew off the marsh and inland throughout our four hour stay. We were reliably informed that recent counts have been in the region of 40,000 Pink-footed Geese!

Pink-footed Geese

Seems like we have enough pinkies for a while. But if anyone would like to send more Linnets our way, we'll do our best to accommodate them.




Sunday, November 12, 2017

Bright And Breezy

The forecast said bright and breezy and it was spot-on for birding if not for ringing at our exposed sites. I travelled over the moss roads where I hoped for a Barn Owl or two; but no luck this morning, just a pair of Buzzards leaving their overnight roost.

At Gulf Lane the Linnet flock has increased to 200+ birds but no sign of the Stonechat from earlier in the week. With luck we’ll get a crack at catching more Linnets this coming week. Lapwings and Curlews filled the wet fields alongside the A588 with several hundred of each before I even reached Braides Farm.

Here at the farm were 500+ Lapwing and similar numbers of Curlew, and on the flood itself, 80+ Black-tailed Godwit. A mile away I stopped on the rise of Bank End Lane and viewed the fields below. Here were several hundreds more of both Lapwing and Curlew, dozens of Redshank, and once again a large number of Black-tailed Godwit, 130 or more.

The area around Chris the farmer’s midden/slurry pond is holding a good number of insects as well as small birds, mainly pipits and wagtails, but also a few Tree Sparrows and Reed Buntings. After a while the count came to 120 Meadow Pipit, 8 Pied Wagtail, 1 Grey Wagtail, 4 Tree Sparrow, 2 Reed Bunting and a good number of Starlings.

Pied Wagtail

Grey Wagtail

Grey Wagtail

Meadow Pipit

Meadow Pipit
 
Pied Wagtail

Starling

There is a huge southerly migration of Meadow Pipits during August to October, a movement involving birds from Scotland, Scandinavia and Iceland, after which the UK wintering population is quite small. No one is quite sure of the origins of any wintering birds and their numbers can vary enormously according to the severity of the winter. While the weather is mild at the moment whereby there is plenty of insect food, cold and especially frosty weather will see the birds quickly depart south and west.

Meadow Pipit

Conder Pool is pretty much off the boil for now although the cold northerly appeared to have increased the Teal count to 230 together with the first Wigeon (15) for some weeks. Otherwise - approximately 30 each of Lapwing, 30 Redshank and Curlew, 3 Little Grebe, 2 Goosander, 2 Little Egret and 1 Kestrel. Two Ravens flew over heading inland and in a north easterly direction.

There is such a spectacle of noise and activity that it is hard not to drive up Moss Lane where the Whooper Swans have made their winter home. With 450+ Whoopers and a few dozen Mutes there’s enough action to satisfy most observers, the only problem being to isolate a single photo subject  or small group from the multitude packed into the field.

Whooper Swan
 
Just along Slack Lane there was quite a lot of activity around the now redundant set aside field and hedgerow with more Meadow Pipits, Pied Wagtails, Linnets, and even half-a-dozen Greenfinch. It’s not so many years ago that most birders, me included, didn’t bother to record the overly common Greenfinch in their notebooks. Look at it now – a sharp population decline, a now scarce sight and a rare visitor to many a garden.

Greenfinch - BTO

Greenfinch

On the way back up Moss Lane and around Jeremy Lane were hundreds of very mobile Fieldfares. They tried to feed in the roadside hedgerows but fled as each vehicle whooshed by. My estimate of 3/400 is just that. There could have been lots more but they weren’t in the mood for stopping.

Fieldfares

Fieldfare

A successful morning then!  I really should get out more often.

Linking today to World Bird Wednesday.


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