Showing posts with label sparrows. Show all posts
Showing posts with label sparrows. Show all posts

Thursday, 19 July 2012

Twitchers in a flap as two rare white sparrows appear in Moray garden


A Moray woman who photographed a rare white fledgling sparrow in her garden last week was left ‘stunned’ when a second white bird turned up.
Thought to be a ‘one-in-a-million’ rarity, the white sparrows have a condition known as leucism that leaves their feathers either partly or completely white.

While such birds have been spotted before around the world, intensive internet searches have so far revealed no previous instances where more than a single bird has been seen at the same spot.
Linda Crowther captured images of two of the birds being fed by a parent at the weekend – and she is convinced that there is an older third sparrow visiting.
She said: “I have kept a close watch for the original white sparrow and was stunned when, not one but, two turned up. They are almost identical and were being fed by the same adult male.
“It is causing quite a stir around the neighbourhood and we’ve already had a few bird enthusiasts stopping by to ask about the original bird.
“I also spotted what appears to be a third white sparrow, that one looks slightly less plump than the fledglings and is helping itself to seed and nuts from my bird feeders.”
A spokeswoman for the RSPB said this morning that they could not confirm if there had been any previous sightings of two white sparrows.
She added: "Leucistic birds can be an unusual and exciting sight, so to see two at once is doubly thrilling.
"The fact that these birds have been spotted in the same place with the same condition suggests they are more than likely from the same brood. Sadly, the chances of these birds surviving through to next year's breeding season is unlikely as their unusual white plumage makes them highly vulnerable to predation."


Tuesday, 29 May 2012

For Monogamous Sparrows, It Doesn't Pay to Stray (but They Do It Anyway)

ScienceDaily (May 22, 2012) — It's quite common for a female song sparrow to stray from her breeding partner and mate with the male next door, but a new study shows that sleeping around can be costly.

The 20-year study, which is reported in The American Naturalist, found that offspring conceived outside sparrows' social pairs go on to have lower reproductive success than within-pair offspring. The findings throw a monkey wrench into theories about why ostensibly monogamous animals might be inclined to cheat.
Most bird species display some form of monogamy. Bonded pairs stay together for a breeding season, a few seasons, or sometimes for life. But beneath this veneer of monogamy, there's plenty of hanky-panky in most species. Why promiscuity exists in monogamous species is "one of the biggest remaining enigmas in evolutionary ecology," said Jane Reid, a research fellow at the University of Aberdeen and one of the study's authors.
One hypothesis for this is that when a female strays she makes it count by mating with a male of higher genetic quality than her social mate. The result is higher-quality offspring that have a better chance of carrying a female's genes into future generations. This study, however, turns that explanation on its head.

Wednesday, 4 April 2012

Sparrows Change Their Tune to Be Heard in Noisy Cities

ScienceDaily (Apr. 2, 2012) — Sparrows in San Francisco's Presidio district changed their tune to soar above the increasing cacophony of car horns and engine rumbles, details new Mason research in the April edition of Animal Behaviour.



"It shows a strong link between the change in song and the change in noise," says David Luther, term assistant professor in Mason's undergraduate biology program. "It's also the first study that I know of to track the songs over time and the responses of birds to historical and current songs."
The study, "Birdsongs Keep Pace with City Life: Changes in Song Over Time in an Urban Songbird Affects Communication," compares birdsongs from as far back as 1969 to today's tweets. Plus, the researchers detail how San Francisco's streets have grown noisier based on studies from 1974 and 2008.
Luther wrote the study with Elizabeth Derryberry, an assistant professor of ecology and evolutionary biology at Tulane University and a research assistant professor at Louisiana State University's Museum of Natural Science. "We've created this artificial world, although one could say it's the real world now, with all this noise -- traffic, leaf blowers, air conditioners," Luther says. "A lot of birds are living in these areas, and what, if anything, is this doing to their songs?"
Turns out, quite a bit.

Monday, 19 September 2011

Italian sparrow joins family as a new species

Scientists in Norway say they have conclusive genetic evidence that sparrows recently evolved a third species.

The Italian sparrow, they argue, is a cross between the ubiquitous house sparrow and the Spanish sparrow.

Whether it is a distinct species has been the subject of a long scientific debate.

The Oslo team say in the journal Molecular Ecology that their evidence resolves the question.

Many bird-watching guides already identify the Italian sparrow as a separate species.

But this study, led by evolutionary biologist Glenn-Peter Saetre from the University of Oslo, is a genetic snapshot that appears to settle the debate.

The researchers studied populations of Italian and Spanish sparrows that share the same habitat in the south-east of Italy.

They took blood samples from the birds in order to extract DNA.

"By examining the genetics, we have shown conclusively that the Italian sparrow is of mixed origin - it is a hybrid of the house sparrow and the Spanish sparrow," Dr Saetre told BBC Nature.

"Second, and perhaps equally important - it is not reproducing with the Spanish sparrow, even though the two birds live side-by-side."

If the birds had been breeding, the scientists say that they would have found genetic "intermediates" - birds with genes from both species.

"But we didn't find this, so we think [the two species] have formed some kind of reproductive barrier to each other," Prof Saetre said.

"Either the [Italian sparrows] just don't like the look of the [Spanish sparrows] or perhaps they have evolved a different breeding season.

"We're not sure what the reason is, but they are not reproducing."

In evolutionary biology, the definition of a distinct species is not entirely clear-cut.

William Amos, professor of evolutionary genetics at the University of Cambridge, explained: "I think the best definition we have is the one that says that different species are those that, under natural conditions, tend not to interbreed.

"Because as soon as you have interbreeding, all those barriers [between those groups of animals] break down."

If Italian sparrows have indeed stopped reproducing with Spanish sparrows, they will gradually, generation by generation, become even more genetically distinct.

As well as providing strong evidence of this rare event - termed speciation - the scientists believe the research shows that the crossing of two species to form a new one might be "more common in nature than previously assumed".


http://www.bbc.co.uk/nature/14947902

Thursday, 19 August 2010

Mystery of the vanishing sparrows still baffles scientists 10 years on

The greenfinch may be declining because of a parasitic disease, but nobody knows – still – the reason for the decline of the house sparrow.

It was once our most common and familiar bird. Now, in many places, it has vanished. Yet, more than 10 years after The Independent offered a prize of £5,000 for a proper scientific explanation of the house sparrow's widespread disappearance from many of our towns and cities, London above all, its vanishing remains one of the great environmental mysteries.

Yesterday, for example, there were no sparrows visible in London's Trafalgar Square, whereas 25 years ago the major tourist destination scattered with sandwich crumbs was full of them – as similar sites in major cities around the world are full of them still.

In the 1990s London's house sparrows entered a sudden and sharp decline until, by the turn of the century, they had virtually disappeared from the capital – the last pair of sparrows in St James's Park, packed with other birds, nested in 1998.

When this newspaper launched its "Save The Sparrow" campaign on 16 May 2000, it made international headlines. The fact that the cheeky "Cockney sparrer", the street smart urban survivor par excellence, was no longer surviving in urban habitats, caught people's imagination, not least because their disappearance may resemble the miner's canary – a warning of some unknown and wider danger. If something in the urban environment was devastating sparrows, what was it doing to us?

However, we did not succeed immediately in drawing out definitive explanations. Suggestions for the reason behind the decline ranged from the increase in suburban predators such as magpies, sparrowhawks and cats to the trend in "tidying up" houses and gardens leaving fewer nesting spaces. Disease, mobile phone radiation and insect decline were also posited.

It was not until 2008 that we had a serious entry for the prize, for which the rules were fairly stiff – the explanation had to be in a paper published in a peer-reviewed scientific journal, and accepted by our referees, the Royal Society for the Protection of Birds (RSPB), the British Trust for Ornithology, and the world expert on sparrows, Dr Denis Summers-Smith.

The 2008 entry was based in the work of a young postgraduate student, Kate Vincent, whose 2005 PhD thesis at De Montfort University in Leicester showed that sparrow chicks in some places were dying of starvation in their nests because of the lack of suitable insect food, such as aphids.

Her data, analysed intensively by senior ornithologists led by Dr Will Peach of the RSPB, formed the basis of a paper in the journal Animal Conservation which was submitted for the prize. But of our three referees, one thought it merited the award, one thought it did not, and one thought it merited half the award. It was certainly a serious contender, but as it was possible that another entry might secure the prize unanimously, we felt the award should be held back.

The other entry, submitted earlier this year from Christopher Bell, an independent scientific researcher, and other scientists, was published as a paper in the online version of Auk, the journal of the American Ornithologists' Union, and suggested that the cause of the decline was predation by sparrowhawks. It was rejected by all three referees.

In March, Dr Summers-Smith circulated a note to researchers interested in the sparrow's disappearance, summarising all the theories and suggestions of the last 10 years. His own view is that insect decline, leading to chick mortality, is "a primary factor" but as he says himself: "It is a necessary, but not a sufficient condition."

He feels that other factors must be involved, and that the insect decline has not been properly explained (his own belief is atmospheric pollution).

The most puzzling aspect of the affair remains the suddenness of the decline in the 1990s, when London's sparrow population fell off a cliff. What can have caused it? The introduction of lead-free petrol (containing other harmful chemicals)? The introduction of mobile phones? That does not explain why house sparrows are still numerous, for example, in New York and Washington.

You tell us. The prize remains to be claimed.

Tuesday, 20 July 2010

'Alarming decline' among London's house sparrows

20 July 2010

There has been an "alarming decline" in sparrows in London, the Royal Society for the Protection of Birds has said.

Its annual survey of the population of breeding birds has found a 68% drop in numbers compared with 15 years ago.

But it is unclear why this is the case, the society said, and a research project has been started.

Several species are on the increase, including robins, blue tits and magpies. The number of goldfinches has nearly trebled since 1995.

The number of house sparrows and song thrushes has declined more than in any other part of England, the report found.

This was "alarming", said the society's spokesman, Tim Webb.

"Their numbers are very low compared with historic levels and no-one knows why.

"Whatever is affecting them could be having an impact on our health and the wider environment," he added.

http://www.bbc.co.uk/news/uk-england-london-10695372
(Submitted by Liz R)
Related Posts with Thumbnails

ShareThis