No death of birds in Gwalior and Delhi Zoo: Committee

The committee said that there has been no reports of any deaths of birds in the last 24 hours from National Zoological Park and Deer Park in New Delhi and Gwalior Zoo.

New Delhi: Chickens ready to be sold in the wake of Bird Flu apprehension at Gazipur Murga Mandi in Delhi on Saturday. PTI Photo by Atul Yadav(PTI10_22_2016_000038B)

The committee constituted by Centre to monitor the avian flu situation on Tuesday said no death of birds have been reported from Delhi or Gwalior zoos in the last 24 hours even as the Union Health Ministry issued a health alert to states seeking to minimise the bird-human interface to prevent outbreak of bird flu. The three member committee which was set by the Union Environment Ministry to monitor the avian flu situation in its review today said that scientists from National Institute of Virology in Pune have visited the zoos and collected samples.

The committee said that there has been no reports of any deaths of birds in the last 24 hours from National Zoological Park and Deer Park in New Delhi and Gwalior Zoo.

“Pelicans kept with the painted storks in Gandhi Zoological Park in Gwalior have been kept in quarantine and all of them are in good health. The samples from other birds of Gwalior zoo were sent to the National Institute for High Security Animal Diseases (NIHSAD) in Bhopal. The report of the same is still awaited,” an official statement said.

Acting on reports of mortality among the birds, in the Delhi NCR region and other parts of the country due to H5 Avian Influenza Virus, Union Environment Minister Anil Madhav Dave had constituted a monitoring committee.

The committee comprises of member secretary of Central Zoo Authority, director National Zoological Park and deputy Inspector General of Forest (Widlife).

The memorial of former Prime Minister Indira Gandhi, Shakti Sthal, had to be closed in the national capital today as two more ducks succumbed to suspected avian influenza there, taking the toll in the national capital to 66.

“A team of scientists from National Institute of Virology (NIV) Pune, Indian Council of Medical Research (ICMR Institute) visited the zoo today and collected samples,” the statement said.

The committee had yesterday said that six painted storks and two ducks had died of birdflu at Gwalior zoo and Deer Park in Delhi respectively.

The statement said that there has been continued surveillance and the zoos are being screened regularly for any dead bird while bio-security measures are being strictly enforced.

“Mortality Status within 24 hours – National Zoological Park in New Delhi – nil, deer park in Hauz Khas in New Delhi – nil and Gwalior zoo – nil,” the statement said.

“National Zoological Park, Delhi, Gandhi Zoological Park, Gwalior and AN Jha Deer Park, Hauz Khas, Delhi remained closed for the safety of visitors and control of the disease.

Many Evolutionary Paths Lead to Same Bird Trait

Diverse genetic changes lead to remarkably similar hemoglobin adaptations of diverse bird species, a study finds.

A sparkling violetear hummingbird, native of the Andean highlands.BRIAN ZWEIBEL

Many more genetic changes can result in the same phenotype than previously suspected, according to a study of birds spanning 56 divergent species. Analyzing the structure and function of their hemoglobin proteins, Jay Storz of the University of Nebraska, Christopher Witt of the University of New Mexico, and their colleagues uncovered a wide breadth of mutations that all resulted in higher hemoglobin affinities for oxygen among birds living at high altitudes. The results were published today (October 20) in Science.

“This study is a beautiful look at the molecular basis of convergent evolution,” Joel McGlothlin, who studies evolution at Virginia Tech and was not involved in the work, wrote in an email to The Scientist. “Amazingly enough, there appear to be a huge number of different molecular routes to greater oxygen affinity, and birds seem to have explored many of them.”

“Other researchers have looked at examples of convergent evolution, but [these authors] have looked across a really wide taxonomic diversity in a single paper, which is really unique and unusual,” Jamie Bridgham of the Institute of Ecology and Evolution at the University of Oregon, who also did not participate in the study but who penned an accompanying editorial, told The Scientist.

Storz, Witt, and their colleagues sought to understand whether there are many different ways genes can evolve to the same hemoglobin function. The researchers collected 56 bird species from the Andes and Rocky Mountains and sequenced the three genes that make up the hemoglobin subunits. Considering the species as 28 related pairs—one species that lives at high altitudes and one lowland species, the team found that, as expected, the high-altitude bird of each pair had a higher affinity for oxygen, but of the 28 high-altitude species, only four had the same amino acid changes.

Because few amino acid changes were thought to affect the hemoglobin protein’s oxygen affinity, researchers had assumed that the evolution of the underlying genes was predictable. But the authors of the new study unexpectedly found that many of these amino acid changes were not in the active site of the protein that interacts with oxygen. 

“We were addressing whether genetic evolution is predictable and we found that evolutionary changes may be highly predictable at the at the level of biochemical phenotype, but that there can be far less predictability at the underlying genetic level,” Storz explained.

He and his colleagues then tested whether the observed hemoglobin mutations were affected by the sequences already present within the hemoglobin genes. They introduced the most common mutation (found in hummingbirds and a flowerpiercer species) into a plasmid encoding the ancestral hummingbird hemoglobin genes, then expressed and purified the protein and found that it had a higher affinity for oxygen. The same mutation introduced into a more ancestral avian hemoglobin gene did not increase the protein’s affinity for oxygen, however.

“An important implication of our work is that, for any given gene, the substitutions accumulated through evolutionary history determine the set of mutations acceptable or beneficial in the future,” said Storz. “The evolutionary mutation options available to one species may not be available to another.”

“The different paths that evolution takes depend on a lineage’s evolutionary history, with molecular changes in the distant past opening or closing doors for particular changes in the future,” agrees McGlothlin.

Both Bridgham and McGlothlin agreed that this study is particularly powerful because the hemoglobin system is relatively simple and the phenotype—oxygen binding—can be readily tested and quantified with reconstituted proteins in the laboratory. “The authors could ask how changes in DNA sequence translated into changes in function not only in living species but also in extinct ones,” McGlothlin wrote in an email to The Scientist. “Even more impressively, they could apply mutations to explore evolutionary what-if scenarios that would be impossible in many other systems.”

Bridgham would next like to see studies to understand whether these findings are generalizable to other proteins and range of other species, as well as to more complex traits involving a larger set of connected genes.

McGlothlin, on the other hand, is interested in the molecular changes that allowed different birds to acquire specific genetic changes in hemoglobin. “The authors have provided a beautiful example of how we can make sense out of unpredictability by looking at deep evolutionary history,” wrote McGlothlin.

Anna's Hummingbird

Calypte anna

Since the 1950s, has expanded its breeding range both north and east. Very common in much of its range, adapting well to suburban areas.

Family Hummingbirds

Habitat Gardens, chaparral, open woods. Found in a wide variety of habitats within its range, including streamside groves, chaparral, open oak woodland, coastal sage scrub, gardens, city parks. Most common in lowlands and lower mountain slopes, but may wander to high mountain meadows in late summer.

This hardy little bird is a permanent resident along our Pacific Coast, staying through the winter in many areas where no other hummingbirds are present. More vocal than most hummingbirds, males have a buzzy song, often given while perched. In recent decades the species has expanded its range, probably helped along by flowers and feeders in suburban gardens; it now nests north to British Columbia and east to Arizona.

കോഴിയിട്ട ആനമുട്ട

യുകെയിലെ പീറ്റര്‍ബര്‍ഗിലുള്ള മൂന്നു വയസുകാരിയായ ബി.ബി എന്ന കോഴിയാണ് ആനമുട്ടയിട്ട് ഉടമയെ ഞെട്ടിച്ചു കളഞ്ഞത്. 51 കാരിയായ അലിസൺ സാവിഡ്ജിന്റെ വീട്ടിൽ വളർത്തുന്ന കോഴിയാണിത്. ബ്രിട്ടനിലെ തന്നെ ഏറ്റവും വലിയ മുട്ടയാണു ബി.ബി ഇട്ടതെന്നാണു കരുതുന്നത്. സാധാരണ കോഴിമുട്ടയുടെ 4 ഇരട്ടി വലിപ്പമുണ്ട് ബി.ബിയുടെ ഈ ആനമുട്ടയ്ക്ക്. 240 ഗ്രാം ഭാരമുള്ള മുട്ടയുടെ നീളം 3.80 ഇഞ്ചാണ്. വലിപ്പം ഏതാണ്ട് 8 ഇഞ്ചു വരും.

ബി.ബിയുടെ ഉടമസ്ഥയായ അലിസണ്‍ ആണ് ആനമുട്ട ആദ്യം കണ്ടത്. താറാമുട്ടയാണോ എന്നു തുടക്കത്തില്‍ സംശയിച്ചെങ്കിലും പിന്നീട് ബി.ബി തന്നെയാണ് മുട്ടയുടെ അവകാശിയെന്നു വ്യക്തമായി. മുട്ടയുടെ വലിപ്പത്തില്‍ മാത്രമല്ല ഇടുന്ന മുട്ടകളുടെ എണ്ണത്തിലും ബി.ബി ഒരു പടി മുന്നിലാണെന്ന് ഉടമ പറയുന്നു. ബ്ലാക്ക്മാരന്‍ ഇനത്തില്‍പ്പെട്ട കോഴിയാണ് ബി.ബി.

ബ്രിട്ടനില്‍ ഇതുവരെ രേഖപ്പെടുത്തിയ ഏറ്റവു തൂക്കമുള്ള മുട്ട 194 ഗ്രാമാണ്. ഈ റെക്കോഡാണ് 240 ഗ്രാം തൂക്കമുള്ള ബി.ബിയുടെ മുട്ട തകർത്തിരിക്കുന്നത്. ലോക ചിക്കന്‍ ദിനമായ ഒക്ടോബര്‍ 13നാണ് ബി.ബി ഈ ആനമുട്ട ഇട്ടതെന്ന പ്രത്യേകതയുമുണ്ട്.

Aussie Backyard Bird Count has eye on ibis and cockatoos

The white ibis might be the bane of picnic goers and workers on their lunch break, but they are one of the birds researchers are keeping a close eye on during National Bird Week.

Researchers are calling on all residents across Australia to take part in the Aussie Backyard Bird Count from October 17 to 23.

The week-long census requires people to count and identify the birds they see in their garden or park and report their findings via the Aussie Bird Count app or website.

"We want to know what's happening in people's backyards," Holly Parsons, Birds in Backyard Count program manager, said.

"Australia is one of the most urbanised countries in the world, we're continuing to take up more space for ourselves and leaving wildlife with nowhere to go.

"Gardens, the habitats in our cities are one way to help as many species as possible.

"We need to know what's there so we know how to better manage habitat and how to create spaces for them."

This is the third year the national bird survey has taken place.

Last year, 42,000 people recorded their sightings and reported 1 million birds across Australia.

The rainbow lorikeet, noisy miner and the magpie were the most common birds.

Ms Parsons said they hoped to record at least 1.5 million birds this week.

Big white birds

In a separate study, ecologists from the Sydney Botanic Gardens will use data from the Aussie Backyard Bird Count to study the white ibis and the sulphur-crested cockatoo.

Dr John Martin said they wanted to better understand the distribution and abundance of the ibis and cockatoo population across New South Wales and the country.

He acknowledged the ibis was one of the birds most people loved to hate.

"The Australian white ibis has shifted to the urban environment.

"A few decades ago it was uncommon to see the white ibis — they're not always loved.

"We need to learn about the distribution of the species ... and about the pockets they are moving into."

There were 23,000 ibises counted last year and 20,000 sulphur-crested cockatoos.

Dr Martin said that in the 1980s, white ibises were mainly found in the western wetlands across the eastern states.

Since then their numbers have dramatically declined due to habitat degradation and the birds shifted into urban areas.

Similarly, cockatoos have moved into the cities in the past 10 years.

"We're cutting down our big old trees and clearing hollows ... the species isn't currently at risk but importantly its habitat is at risk," Dr Martin said.

"These are generational issues, it would be great if they are on people's radars."

What bird is that?

The Aussie Bird Count app allows people to add descriptions and match birds against visual criteria — helpful if they are unable to identify the species.

In Sydney, Ms Parsons said residents might be lucky to spot a powerful owl in their tree.

"It's a threatened species, a nocturnal bird, but will sit in the tree during the day so you can do the survey night and day," she said.

More common birds that might fly into people's backyards include the sulphur-crested cockatoo, Australian magpie, currawongs, Australian raven, rainbow lorikeets and red wattle bird.

In wetland areas, Dr Martin said the purple swamphen, coot, black swan, Pacific black duck and masked lapwing may be spotted.

Smaller birds include the willy wagtail, fairywren, Indian myna, pigeons, crested pigeon and peaceful dove.

തിരികെ പോകാൻ കൂട്ടാക്കാത്ത പക്ഷി; അറിയാം ഈ അപൂർവ സൗഹൃദം

രണ്ടു വർഷം മുൻപാണ് തടാകത്തിൽ മുങ്ങിത്താണു കൊണ്ടിരുന്ന വാത്തക്കുഞ്ഞിനെ മൈക്ക് ജിവാൻജീ രക്ഷിച്ചത്. ഓറിഗണിലെ ഓസ്‌വിഗോ തടാകത്തിൽ നിന്നാണ് മൈക്കിനു വാത്തക്കുഞ്ഞിനെ കിട്ടിയത്. ഒറ്റപ്പെട്ട വാത്തക്കുഞ്ഞിനെ മറ്റു വാത്തകളുടെ വാസസ്ഥലത്തെത്തിച്ചെങ്കിലും അവർ കൂടെ കൂട്ടാൻ തയാറായില്ല. അങ്ങനെയാണ് മൈക്ക് വാത്തക്കുഞ്ഞുമായി വീട്ടിലേക്കു പോയത്. പിന്നീടിതിന് കൈൽ എന്നു പേരുമിട്ടു. ആരോഗ്യം വീണ്ടെടുത്തു പറക്കാറാകും വരെ വാത്തയെ സംരക്ഷിക്കാമെന്നാണ് മൈക്ക് കരുതിയത്. എന്നാൽ ആരോഗ്യം വീണ്ടെടുത്തെങ്കിലും മൈക്കിനെ വിട്ടു പോകാൻ കൈൽ തയാറായില്ല. കൈലിനെ സ്വതന്ത്രയാക്കി വനത്തിലേക്കു തിരികെ അയയ്ക്കാൻ പഠിച്ചപണി പതിനെട്ടും പയറ്റിയിട്ടും നടന്നില്ലെന്നു മൈക്ക് പറയുന്നു. ഓരോ തവണയും മൈക്ക് കൈലിനെ ദൂരെസ്ഥലങ്ങളിൽ കൊണ്ടുവിട്ടിട്ടു വരുമ്പോഴും മൈക്കിനേക്കാൾ മുമ്പിൽ കൈൽ വീട്ടിലെത്തിയിരിക്കും. ഒടുവിൽ മൈക്ക് ആ ശ്രമം ഉപേക്ഷിച്ചു.

പറക്കാൻ പഠിച്ചതു മുതൽ പകൽ സമയം എവിടെയെങ്കിലുമൊക്കെ പോകുമെങ്കിലും വൈകുന്നേരമാകുമ്പോൾ മൈക്കിനരികിൽ തിരികെയെത്തും. മൈക്കാണു കൈലിന്റെ ലോകമെന്നു പറയാം. മൈക്ക് എവിടെ പോയാലും കൈൽ പിന്തുടരും. ബോട്ടിങ്ങിനു പോയാൽ ക‍ത്യമായി ആ ബോട്ടിനരികിലെത്തും. ഷോപ്പുകളിലും റോഡിലുമൊക്കെ മൈക്കിനൊപ്പം കറങ്ങുകയാണു കൈലിന്റെ വിനോദം.

ചിലപ്പോൾ മനുഷ്യരുടേതു പോലെയാണു കൈലിന്റെ സ്വഭാവമെന്നും മൈക്ക് പറയുന്നു. മൈക്കിനരികിൽ പെൺകുട്ടികൾ വരുന്നതൊന്നും കക്ഷിക്ക് ഇഷ്ടമല്ല.എന്നാൽ എല്ലാവരോടും ഇഷ്ടക്കേടുമില്ല. ചിലരോടു മാത്രമാണ് അപ്രിയം. മൈക്കിന്റെ മിക്ക പെൺ സുഹൃത്തുക്കളോടും കൈലിനു വിരോധമൊന്നുമില്ല. അവരോടൊപ്പവും കൈൽ സമയം ചിലവഴിക്കാറുണ്ട്. എന്നാൽ ദേഷ്യം വരുന്ന സന്ദർഭങ്ങളിൽ എന്താണു ചെയ്യുന്നതെന്നു കൈലിനു പോലും നിശ്ചയമുണ്ടാവില്ല. ചിലപ്പോൾ മറ്റു ബോട്ടുകളിൽ കയറി ബഹളമുണ്ടാക്കും ഇല്ലെങ്കിൽ അയൽവീട്ടിൽ അതിക്രമിച്ചു കടന്ന് എന്തെങ്കിലും മോഷ്ടിക്കും ഇതൊക്കെയാണു കൈലിന്റെ കലാപരിപാടികൾ. കീചെയിനും വാലറ്റും പോലുള്ള ചെറിയ സാധനങ്ങൾ അയൽവീടുകളിൽ നിന്നു മോഷ്ടിച്ചു വെള്ളത്തിടുന്നത് കൈലിന്റെ പ്രധാന വിനോദമാണെന്നും മൈക്ക് പറയുന്നു.

വീട്ടിൽ ഒന്നിച്ചുള്ള സമയങ്ങളിൽ ടിവികാണുകയാണു ഇരുവരുടെയും പ്രധാന പരിപാടി. ഡിസ്കവറിയും ആനിമൽ പ്ലാനറ്റുമാണ് കൈലിനേറെയിഷ്ടം. അയൽക്കാർ അവധിക്കാലമാഘോഷിക്കാൻ പോകുമ്പോൾ അവിടെ ചുറ്റിത്തിരിയാനും കൈലിനിഷ്ടമാണ്. എന്തായാലും ഇണക്കങ്ങളും പിണക്കങ്ങളുമായി ഇരുവരുടെയും ജീവിതം സന്തോഷത്തോടെ മുന്നോട്ടു പോകുന്നു. 

തൂവലുകളില്ലാത്ത തത്തക്കുഞ്ഞാണ് ഇന്‍സ്റ്റഗ്രാമിലെ താരം

ബഹുവർണങ്ങളിലുള്ള തൂവലുകളാണു പക്ഷികളുടെ സൗന്ദര്യത്തിനു മാറ്റു കൂട്ടുന്നത്. മഞ്ഞിൽ നിന്നും മഴയിൽ നിന്നും വെയിലിൽ നിന്നുമൊക്കെ ഇവർക്കു സംരക്ഷണം നൽകുന്നതും ഈ തൂവലുകളാണ്. ചുരുക്കി പറഞ്ഞാൽ പക്ഷികളുടെ വസ്ത്രങ്ങളാണു തൂവലുകള്‍ എന്നു പറയാം .അപ്പോള്‍ തൂവലില്ലാത്ത പക്ഷിയെ എന്തു വിളിക്കണം? അങ്ങെനെയൊരു പക്ഷിയുണ്ടാകുമോ എന്നാണു ചോദ്യമെങ്കിൽ തെറ്റി. പക്ഷികളിൽ ഏറ്റവും സൗന്ദര്യമുള്ള തത്തകളുടെ ഗണത്തിലാണ് തൂവലുകളില്ലാത്ത ഈ തത്തക്കുഞ്ഞുള്ളത്.

പക്ഷെ തൂവലില്ലാത്തതിനാല്‍ തനിക്കു സൗന്ദര്യമില്ലെന്നു പറഞ്ഞു വിഷമിച്ചിരിക്കുകയല്ല റിയ എന്ന ഈ മിടുക്കി തത്ത. ഇന്‍സ്റ്റഗ്രാമില്‍ മാത്രം റിയയെ പിന്തുടരുന്നത് ഒന്നര ലക്ഷത്തോളം ആരാധകരാണ്. തൂവലുകളില്ലെങ്കിലും ഓരോ ദിവസവും വ്യത്യസ്തമായ വസ്ത്രങ്ങളണിഞ്ഞാണ് റിയ ഇന്‍സ്റ്റാഗ്രാമില്‍ പ്രത്യക്ഷപ്പെടുന്നത്. റിയയ്ക്കായി ഫാഷന്‍ വസ്ത്രങ്ങളൊരുക്കി ചിത്രങ്ങളെടുക്കുന്നതും സമൂഹമാധ്യമങ്ങളിൽ അവ പോസ്റ്റു ചെയ്യുന്നതും റിയയെ എടുത്തു വളര്‍ത്തുന്ന ഇസബെല്ലയാണ്.

വൈറസ് ബാധയാണ് റിയയുടെ തൂവലുകള്‍ പൊഴിയാനുള്ള കാരണം. പിങ്ക് നിറത്തിലുള്ള തന്‍റെ ശരീരവും തലയേക്കാള്‍ വലിയ കൊക്കുമായി നിന്ന റിയയെ മാസങ്ങള്‍ക്ക് മുന്‍പാണ് ഇസബെല്ല ബോസ്റ്റണിലെ മൃഗാശുപത്രിയിൽ നിന്നു വളര്‍ത്താനായി ഏറ്റെടുക്കുന്നത്. തൂവലുകള്‍ ഇല്ലാത്തതിനാല്‍ താപനിലയിലെ വ്യത്യാസങ്ങള്‍ ബാധിക്കുന്നതാണു റിയ നേരിടുന്ന പ്രധാന ആരോഗ്യപ്രശ്നം.

ഇതു മറികടക്കാന്‍ തത്തയുടെ രൂപത്തിനനുയോജ്യമായ കമ്പിളിപുതപ്പും മറ്റും ഇസബല്ല തയ്യാറാക്കിയിട്ടുണ്ട്. കൂടാതെ ഭക്ഷണ കാര്യത്തിലും പ്രത്യേകം ശ്രദ്ധിക്കും. ഇസബല്ല തയ്യാറാക്കുന്നതു കൂടാതെ തത്തയെക്കുറിച്ചു സമൂഹമാധ്യമങ്ങളിലൂടെയറിഞ്ഞ് നിരവധി പേരാണ് റിയയ്ക്കു വേണ്ടി സ്വെറ്ററുകളും മറ്റും തയ്യാറാക്കി അയയ്ക്കുന്നത്. എന്തായാലും തൂവലുകളില്ലെങ്കിലും റിയ ഹാപ്പിയാണ് ഒപ്പം ഇസബെല്ലയും.

Oldest known squawk box suggests dinosaurs likely did not sing

Study of the first fossil vocal organ from the Mesozoic provides insight into the evolution of bird calls and song. The fossil syrinx is from the late Cretaceous of Antarctica. Within dinosaurs there was a transition from a vocal organ present in the larynx (present in crocodiles) to one uniquely developed deep in the chest in birds.

Credit: Nicole Fuller/Sayo Art for UT Austin.

The oldest known vocal organ of a bird has been found in an Antarctic fossil of a relative of ducks and geese that lived more than 66 million years ago during the age of dinosaurs.

The discovery of the Mesazoic-era vocal organ -- called a syrinx -- and its apparent absence in nonavian dinosaur fossils of the same age indicate that the organ may be have originated late in the evolution of birds and that other dinosaurs may not have been able to make noises similar to the bird calls we hear today, according to findings published in Nature on Oct 12. Birds are direct descendants of dinosaurs and are considered living dinosaurs by scientists.

"This finding helps explain why no such organ has been preserved in a nonbird dinosaur or crocodile relative," said Julia Clarke, a paleontologist at The University of Texas at Austin Jackson School of Geosciences who discovered the fossil syrinx and led the analysis. "This is another important step to figuring out what dinosaurs sounded like as well as giving us insight into the evolution of birds."

The syrinx is made of stiff, cartilage rings that support soft tissues that vibrate to produce the complex songs and calls of modern birds. Cartilage does not fossilize as well as hard tissues such as bone. But the high mineral content in the syrinx's rings sometimes allows for fossilization. All other known examples of fossilized syrinxes occur in birds that lived well after nonavian dinosaurs went extinct.

The syrinx was found in a fossil of Vegavis iaai, a bird that lived during the Cretaceous. Clarke described the species in 2005. It was discovered on Antarctica's Vega Island in 1992 by a team from the Argentine Antarctic Institute. However, it wasn't until 2013 that Clarke noticed that the Vegavis fossil included a syrinx. During the past two years, the team searched the dinosaur fossil record for other examples of a syrinx, but so far has found none.

The asymmetrical shape of the syrinx indicates that the extinct species could have made honking noises via two sound sources in the right and left parts of the organ. The researchers also scanned syrinxes of other birds to compare with the Vegavis syrinx. This included 12 syrinxes from living birds and the next oldest fossilized syrinx, which had not yet been studied.

Franz Goller, a co-author and physiologist at the University of Utah, said the study is the beginning of the work to determine what the fossilized organ can tell us about the sounds of early birds.

"Here, we begin to outline how fossilizable characteristics of the syrinx may inform us about sound features, but we need a lot more data on living birds," Goller said. "Remarkably, prior to this work, there is almost no discussion of these important questions."

This study follows research that Clarke and other collaborators published in July 2016 that found some dinosaurs would likely have made closed-mouth vocalizations akin to ostrich booms that don't require a syrinx. Together, the two studies have major implications for dinosaur sound-making throughout time, Clarke said.

In addition, the evolution of vocal behavior can give insights into other anatomical features, Clarke said, such as the appearance of bigger brains.

"The origin of birds is about so much more than the evolution of flight and feathers," Clarke said.

To study sound production in more detail, part of the team is working with engineers to model sound-producing organs, a project funded by the Gordon and Betty Moore Foundation.

American Oystercatcher

Haematopus palliatus

Conservation status Numbers declined seriously in 19th century, then recovered well in 20th century. Despite disturbance in beach habitats, the species currently is doing fairly well, often nesting on dredge spoil islands.

Family Oystercatchers

Habitat Coastal beaches, tidal flats. Strictly coastal, in areas with extensive sand beaches, tidal mudflats, salt marsh. Key element is presence of good food supply, such as oyster beds, clam flats. May nest among dunes, on islands in salt marsh, or on dredge spoil islands.

A very large, unmistakable shorebird of Atlantic and Gulf Coast beaches. Solitary or in family groups in summer, American Oystercatchers may gather in large flocks in winter.

Photo Gallery

Feeding Behavior

Often forages by walking in shallow water, searching for food by sight. The birds have two methods of opening the shells of bivalves. In one, finding a mussel with its shell slightly open, the oystercatcher quickly jabs its bill into the opening, cutting the muscles and then cleaning out the contents. In the other method, the bird simply hammers on the shell to break it open.

Eggs

1-4. Buffy gray, usually speckled with dark brown. Nests attended by two females and one male may have 5-6 eggs. Incubation is by both sexes, 24-28 days. Young: Downy young leave nest shortly after they hatch. Both parents feed young for at least 2 months after hatching, although young may attempt to forage on their own well before parents stop feeding them. Age at first flight about 5 weeks.

Young

Downy young leave nest shortly after they hatch. Both parents feed young for at least 2 months after hatching, although young may attempt to forage on their own well before parents stop feeding them. Age at first flight about 5 weeks.

Diet

Mostly shellfish and marine worms. Feeds mostly on mussels, clams, oysters; also marine worms, sand crabs, limpets, sea urchins, jellyfish, and other small creatures of the intertidal zone.

Nesting

First breeds at age of 3-4 years. Sometimes may mate for life. In areas with high populations, may form trios, with one male and two females attending one nest or two nearby nests. Nest site is on ground, on marsh island or among dunes, usually well above high tide mark. Nest (apparently built by both sexes) is shallow scrape in sand, sometimes lined with pebbles, shells.

A Bald Eagle Is Somehow Fine After Getting Stuck in a Moving Car's Grille

The bird, nicknamed Matthew, miraculously escaped with no major injuries and should be released back into the Florida wild soon.

An inconvenienced Matthew the Bald Eagle. Photo: Billi West

In life, sometimes you're the grille, and sometimes you're the Bald Eagle. Alright, so that's not exactly how the saying goes, but it turned out to be true for an unlucky Bald Eagle in Florida this past weekend. 

According to a Facebook post by Florida's Clay County Sheriff's Office on Saturday, a Bald Eagle had to be rescued from the grille of a Saturn after the bird collided with the car and got stuck in the vehicle's lower air intake. Fortunately for the eagle, members of the Sheriff's Office and Fire and Rescue were able to safely remove the raptor. "The bird is alive and was turned over to the B.E.A.K.S. Wildlife Sanctuary," the post said. "Great job by all involved."

Perhaps what's more amazing than the bird’s survival is the fact that the driver apparently didn’t notice hitting the bird in the first place.

Talking to CNN, B.E.A.K.S. owner, Cynthia Mosling, said that another driver at an intersection saw an "odd shape" in the vehicle's grille and thought it was a decorative prop until the bird's head moved. After chasing down the other car to notify its driver that America's national bird was wedged in the front fascia, the good Samaritan dubbed the eagle Matthew for the Hurricane that had brushed Florida's coast the day before. 

In a follow-up interview with The Florida-Times Union on Monday, Mosling said that she was surprised that the bird, an adult male at least seven years of age, didn't have any broken wings or a single broken bone. As of Monday, after having a bit of time to recover from the ordeal, Mosling said Matthew was eating and able to fly to some of the higher perches in his cage. 

"He’s feisty now,” Mosling told The Florida-Times. “His wings are working.”

As soon as Matthew passes a flight test in a larger enclosure, Mosling says she'll release him back to wild, where, if he believes in signs, he'll immediately go buy a Powerball ticket.

Disappearing Ice Means New Ways of Life for Arctic Birds

Arctic seabirds are adapting as climate change brings warmer weather, shifting food sources, and a polar bear invasion.

It’s that time of year again: crisp air, pumpkin lattes, sweaters, and, of course, our annual reminder that the world is gradually getting warmer. At the beginning of each fall, when the Arctic's ice is done melting from the summer heat, the National Snow & Ice Data Center announces how much ice remains (what's called its minimum annual extent). According to this year's announcement, sea ice covered only 1.6 million square miles on September 10, its lowest point for the year. That figure, based on preliminary data, ties this year with 2007 for the second-lowest minimum on record. (For comparison: Between 1979 and 2000, the average minimum was 2.59 million square miles, and the record low was set in 2012 with 1.32 million square miles of ice cover.)

While the announcement of the ever-shrinking Arctic sea ice minimum serves as a clear visual reminder of the earth's warming temperatures, for Arctic wildlife, the picture is more complex. All summer long, the melting ice edge unleashes a rich food source when trapped algae encounters sun-warm water for the first times in months. The resulting algae bloom attracts zooplankton, and then small fish, bigger fish, and top predators such as whales, seals, and seabirds. Changes in the extent and timing of Arctic ice means a shift in food resources, to which birds are adapting and adjusting—some better than others. Here’s how four birds are finding new ways to survive as the icescape around them becomes increasingly unpredictable.

Mandt’s Black Guillemot

Mandt’s Black Guillemots are ice specialists. The birds (pictured above, and a subspecies of the widespread Black Guillemot) roost along the ice edge in the high Arctic, diving for Arctic cod—the preferred food for Arctic predators—and even plucking the fish from cracks in the pack ice. 

But because Arctic cod prefer cold water, they’re now out of reach—too far north or too deep in the water column—when chicks at Cooper Island on the northern tip of Alaska hatch in the summer. So Mandt’s Black Guillemot parents feed their chicks whatever they can catch, and that often means sculpin, a froglike fish that's followed warm water north. Sculpin are bigger than cod, and chicks struggled to swallow their new food at first. Some even choked to death. But guillemot parents seem to be learning. They now bring back smaller sculpin that chicks can swallow. “We were very surprised this past year to have some nests have parents really specialize in sculpin and the chicks have rather decent growth rates,” says George Divoky, who’s monitored the birds with the non-profit Friends of Cooper Island since the 1970s.

As the birds adapt to new food, they must also contend with subarctic invaders moving north as the climate warms. In the 1970s, Divoky noticed Horned Puffins checking out Cooper Island from above, and by the 1980s, the birds had started nesting among the guillemots—and even ousting them. “They started going into the guillemot nests and displacing the eggs and killing the young,” he says. In 2009, they killed nearly half of the guillemot chicks in the colony. “They’re a real climate change signal. It’s good news for the Horned Puffins, but not for the Black Guillemots.”

Ivory Gull

Ivory Gulls are the most northerly breeding birds in the world and the only ones known to nest directly on sea ice—including on icebergs. They migrate along the ice edge to hunt for Arctic cod and small invertebrates that gather there in the summertime bloom.

As sea ice declines, Ivory Gulls seem to be declining, too; their Canadian breeding population shrunk from 2,400 birds in 1987 to 700 birds in 2003, when the most recent survey was completed. The species is listed as endangered in Canada and near threatened on the International Union for Conservation of Nature Red List.

Because they live far from people, it’s hard to say how the population fares overall. But scientists’ predictions aren’t good. “Ivory Gulls are so highly specialized that it’s hard to see what they would do to survive in an ice-free Arctic,” Divoky says. “They’re now dealing with an ice environment that’s very atypical compared to what they’ve had to deal with for the last 10,000 years or so.”

Thick-billed Murre

Thick-billed Murres play the long game. Each May, when they arrive at Coats Island to breed, Hudson Bay is frozen solid around them. The patient parents-to-be will then wait for the ice to melt, and only once open water is exposed nearby do they lay a single egg, finally confident that they can catch enough food to feed their chick. If the water never appears, they fly off without breeding, set on returning and trying again the following spring at the only colony they've nested at for their entire lives.

Like Mandt’s Black Guillemots, Coats Island murres have seen Arctic cod vanish from their summer diets. Since the mid-1990s, Thick-billed Murre parents at Coats Island instead stuff their chicks with capelin, a warmer-water fish, “which they do perfectly well on, but it seems like they don’t do quite as well,” says Tony Gaston, senior research scientist emeritus with Environment and Climate Change Canada who studied Coats Island murres for 30 years. “The chicks are not growing as fast.”

Farther north, Thick-billed Murres stand to benefit from changes in Arctic ice. At Prince Leopold Island, a colony 800 miles north of Coats Island, ice occasionally perseveres throughout the cold summer and prevents the birds from breeding at all. That will change as the Arctic warms. “As those years become less frequent, they will have more breeding years,” Gaston says. “So things are probably improving for the birds in the high Arctic.”

Such improvements could apply to many bird species in the high Arctic—for a time, at least. The slow decline of well-studied nesting colonies might look like loss, but for the most part, populations are merely shifting. Many species will simply move north to stay within their preferred climates—a strategy that can only work for so long. An iceless Arctic summer is expected by 2060, and the birds can’t move north forever. “Eventually it falls off the edge of the world,” Gaston says. “But I don’t worry about Thick-billed Murres. I think they’ll hang on long after we’re gone.”

Common Eider

Unlike colony-nesting seabirds, Common Eiders don’t deliver food to their chicks—they bring the chicks to the food. Just a few days after hatching, eider ducklings follow their parents into open water so they can dive for mollusks on the seafloor. Even after feasting all summer, tragedy can strike during particularly cold winters. When the birds’ feeding areas freeze over, thousands of eiders have little choice but to crowd into the remaining small patches of open water. Beneath that water, food is quickly depleted, and when no other feeding areas are available, Common Eider populations can starve en masse. The loss of Arctic ice is expected to benefit their population: The less ice and the more water available, the better.

However, declining ice also means eider colonies will see more polar bears. The Arctic predator typically uses the sea ice edge as a platform to hunt seals, but the ice's early retreat leaves the bears with less time to hunt big prey. As a result, polar bears have resorted to scavenging for less nutritious food on land, which includes bird eggs. Polar bear visits to the biggest Common Eider colony in the Canadian Arctic increased sevenfold between 1997 and 2012, and at smaller colonies, they’ll devour nearly every egg and chick.

Polar bears gladly raid any seabird colonies within reach, including Thick-Billed Murres at Coats Island and Mandt’s Black Guillemots on Cooper Island. Gaston’s intensive monitoring of birds at Coats Island has ended after 30 years because the bears are too dangerous. “We can’t risk relatively inexperienced students in this kind of situation,” he says. 

While the bears do more damage to colonies of ground-nesting species like Common Eiders, those birds may prove to be more adaptable.

They’re already spreading out within their colonies in Hudson Bay and moving closer to the safety of human settlement—something murres and guillemots are unlikely to do. Those bird species instinctively nest in the same colony year after year. But their chicks, once grown, may take note of the bears and move elsewhere. Gaston thinks first-time murre parents born on Coats Island are already relocating farther north. “What evidence we have suggests that the colony has started to diminish,” he says, and he mostly blames the bears for that.

Some birds behave like human musicians

The pied butcherbird.Credit: Image courtesy of New Jersey Institute of Technology

The tuneful behavior of some songbirds parallels that of human musicians. That's the conclusion presented in a recent paper published by an international team of researchers, among them David Rothenberg, distinguished professor of philosophy and music in NJIT's Department of Humanities. Other members of the team are from the City University of New York (CUNY), the Freie Universität Berlin and Macquarie University in Australia.

"Temporal regularity increases with repertoire complexity in the Australian pied butcherbird's song" was published online in Royal Society Open Science.

A Very Musical Species

The pied butcherbird, a very musical species, provided a wealth of intriguing data for analysis by co-author Eathan Janney, a Ph.D. candidate in the Department of Psychology at CUNY's Hunter College. Janney based his analysis upon years of data collected and also analyzed by violinist and biomusicologist Hollis Taylor of Macquarie University, who has previously published extremely detailed analyses of butcherbird songs. "Since pied butcherbird songs share so many commonalities with human music," Taylor writes, "this species could possibly revolutionize the way we think about the core values of music."

In the past, claims that musical principles are integral to birdsong were largely met with skepticism and dismissed as wishful thinking. However, the extensive statistical and objective analysis of the new paper demonstrates that the more complex a bird's repertoire, the better he or she is at singing in time, rhythmically interacting with other birds much more skillfully than those who know fewer songs. The accompanying video includes a sample of a butcherbird's solo song, as well as the song of another butcherbird and an Australian magpie.

Co-author Ofer Tchernichovski, professor in the Hunter College Department of Psychology, finds that the butcherbirds "balance their performance to keep it in a sweet spot between boredom and confusion." Constance Scharff, a co-author who directs the animal behavior laboratory at the Freie Universität Berlin, says "pied butcherbirds, not unlike jazz musicians, play around with their tunes, balancing repetition and variation." This finding suggests that such musical virtuosity may signify more than just the evolution of a way for birds to establish territorial dominance and facilitate mating. It may also provide evidence that musical ability in birds was a precursor to the evolution of the many dimensions of musical ability in humans.

Inclusive Multidisciplinary Research

The paper is the product of inclusive multidisciplinary research. It integrates input from biologists, neuroscientists, musicians and engineers, including co-author Lucas C. Parra, a member of CUNY's Department of Biomedical Engineering.

Rothenberg, who provided his unique perspective, says, "Science and music may have different criteria for truth, but sometimes their insights need to be put together to make sense of the beautiful performances we find in nature."

Rothenberg has written extensively about the bond between humans and our surrounding natural world, a world we share with myriad other creatures. An earlier paper that he co-authored, "Investigation of Musicality in Birdsong," published in Hearing Research touched upon aspects of the same topic explored in the recent Royal Society publication. Rothenberg's book Why Birds Sing is an in-depth look at the subject that challenges neuroscientists to seriously consider music as a tool to help understand birdsong.

As a musician -- he plays the clarinet and saxophone -- Rothenberg has added the dimension of music to research connecting the living sounds of the natural world to traditions of global rhythmic innovation and improvisation. His book Thousand Mile Song is about making music with whales, and Bug Music, How Insects Gave Us Rhythm and Noise offers the provocative premise that listening to cicadas, as well as other humming, clicking and thrumming insects, fostered an innate sense of musical rhythm and synchronization over the long history of human evolution.

Backyard feeders make life easier for birds in winter

Many of us maintain our birdfeeders throughout the year, regularly restocking them with fresh seed and keeping them clean. Fall, though, is the traditional start of the bird feeding season, and, if you haven’t done so already, now is the time to get started to help the birds through winter.

Even though Georgia’s winters tend to be mild, birds still can use our help — especially during spells of frigid temperatures. All birds require more food in winter just to stay alive. Tiny birds, like chickadees, sparrows, finches and titmice, are particularly at risk in cold weather, because their metabolic rates are high and they have less fat to maintain body heat.

Once the birds learn where they can find dependable food supplies — namely, your feeders — they will continue to return to them during the more severe weather.

Here are some of your questions and the answers from various experts about fall and winter bird feeding:

Q: Will feeding the birds deter them from foraging on their own in the wild?

Hanging feeders now and keeping them well stocked with seed will help birds — such as these female house finches 

A: Not likely. Foraging for food is ingrained in birds. Chickadees, for instance, may get only about 25 percent of their total food needs from backyard feeders; the rest is found in their natural habitat. In winter, birds can still find insects in tree bark, berries on trees and shrubs, and seeds on garden and wild plants. Even so, there is less wild food available during the cold season. So, maintaining a backyard feeder in winter makes the birds’ lives easier and makes our lives more enjoyable.

Q: What is the best type of feeder?

A: If you hang just one feeder, choose a tube feeder — one with metal ports around the seed dispenser to deter squirrels. Hang it at least 5 feet off the ground.

Q: What is the best overall food?

A: Black-oil sunflower seed will attract the widest variety of birds.

Q: Anything else?

A: Yes. Water. Birds need a dependable supply of clean water throughout the year for drinking and bathing. Sources of water include small pools and waterfalls, birdbaths, drippers and misters.

In the sky: From David Dundee, Tellus Science Museum astronomer: The moon will be first-quarter Saturday. Mercury is low in the east just before sunrise. Venus is low in the west at dusk. Mars and Saturn are low in the southwest at dusk.

അച്ഛനെ തട്ടിക്കൊണ്ട് പോയി; സങ്കടം താങ്ങാനാകാതെ കുഞ്ഞു പെന്‍ഗ്വിനുകള്‍ ജീവൻ വെടിഞ്ഞു

പരിസ്ഥിതി സ്നേഹം അതിരു കടന്നാല്‍ സംഭവിക്കുന്ന ദുരന്തമാണു രണ്ടു പെന്‍ഗ്വിന്‍ കുഞ്ഞുങ്ങളുടെ മരണത്തിലേക്കു നയിച്ചത്. അപൂര്‍വ്വ ഇനത്തില്‍പ്പെട്ട ആഫ്രിക്കന്‍ പെന്‍ഗ്വിൻ കുഞ്ഞുങ്ങൾക്കാണ് ഈ ദുര്‍വിധി ഏറ്റുവാങ്ങേണ്ടി വന്നത്. ദക്ഷണാഫ്രിക്കയിലെ ജോഹനാസ് ബര്‍ഗിലെ മൃഗശാലയിലാണു സംഭവം നടന്നത്.

ഒരാഴ്ച മുന്‍പാണു മൃഗശാലയിലെ പെന്‍ഗ്വിന്‍ കുഞ്ഞുങ്ങളുടെ അച്ഛനെ കാണാതായത്. വൈകാതെ പെന്‍ഗ്വിനെ തങ്ങള്‍ തട്ടിക്കൊണ്ടു പോയതാണെന്നു കാണിച്ചു പരിസ്ഥിതി പ്രവര്‍ത്തകരെന്നവകാശപ്പെടുന്ന രണ്ടു പേരുടെ കത്ത് മൃഗശാലയക്കു ലഭിച്ചു.മൃഗങ്ങളെ കൂട്ടിലിട്ടു വളര്‍ത്തുന്നതിനോടുള്ള പ്രതിഷേധമാണിതെന്നും പെന്‍ഗ്വിനെ അതിന്‍റെ സ്വാഭാവിക ആവാസ വ്യവസ്ഥയില്‍ സ്വതന്ത്രമാക്കുമെന്നും കത്തിലുണ്ടായിരുന്നു.

എന്നാല്‍ പരിസ്ഥിതി സ്നേഹത്തിന്‍റെ പേരില്‍ അവർ ചെയ്തത് വലിയ മണ്ടത്തരമായിരുന്നു. അമ്മയില്ലാത്ത ആ രണ്ടു പെന്‍ഗ്വിന്‍ കുഞ്ഞുങ്ങള്‍ക്ക് അച്ഛനായിരുന്നു ഏക ആശ്രയം. അതുകൂടി നഷ്ടമായതോടെ സങ്കടം സഹിക്കാനാകാതെ ഭക്ഷണം ഉപേക്ഷിച്ച കുഞ്ഞുങ്ങൾ ഇന്നലെ ജീവൻ വെടിഞ്ഞു. അച്ഛനെ കാണാതാകുന്നതു വരെ ഇരുവരും ആരോഗ്യവാന്മാരായിരുന്നുവെന്നു മൃഗശാല അധികൃതര്‍ പറഞ്ഞു.

തട്ടിക്കൊണ്ടു പോകപ്പെട്ട പെന്‍ഗ്വിന്‍റെ അവസ്ഥയും വ്യത്യസ്തമാകില്ലെന്നാണു മൃഗശാല അധികൃതര്‍ കരുതുന്നത്. പുറത്തെ ആവാസ വ്യവസ്ഥയില്‍ ജീവിച്ചു പരിചയമില്ലാത്ത പെന്‍ഗ്വിന് അധികനാള്‍ അതിജീവിക്കാനാകില്ലെന്നവര്‍ കണക്കു കൂട്ടുന്നു. അന്ധമായ പരിസ്ഥിതി സ്നേഹത്തിനിടയില്‍ വിവേചനബുദ്ധി നഷ്ടപ്പെട്ടതാണു പെൻഗ്വിൻ കുടുംബത്തിന്‍റെ ദാരുണാന്ത്യത്തിനു കാരണമായതെന്നും അധികൃതർ വിലയിരുത്തുന്നു. 

Birds of prey like hawks and falcons have been used for hunting for thousands of years. Now they are defending Britain’s towns from pests

It is an image that could have come straight from a parliamentary sketch writer's column. While political hawks and doves clash inside the Palace of Westminster, real hawks patrol the skies above the famous buildings to control the population of feral pigeons – which, despite the name, are actually a kind of dove.

But it is not just at the UK's Houses of Parliament that you might see a bird of prey swooping after problem birds. Hawks are also at work around the Scottish Parliament building in Edinburgh and in many other towns up and down the UK – as well as in other countries. Birds of prey have even been deployed in British seaside resorts to keep control of gull populations.

There is simple and seductive logic behind the idea of falconry for bird control. Problem birds – usually pigeons or gulls – recognise a large bird of prey as a threat. As soon as the predator takes to the skies, they scatter.

Pest control is not really seen as a particularly sexy subject

As a result, the problem birds should stay away as long as the bird of prey is flown in the area on a fairly regular basis. The falconer has modified their "landscape of fear", creating a hotspot of terror that they avoid because they associate it with a threat of predation.

Falconry has been used to keep birds away from airportsand landfill sites for decades. Presumably it is effective to some degree, or the operators at these sites would have stopped paying the falconers long ago.

But exactly how effective? The question is not easy to answer because few scientists have investigated falconry for pest control.

Lesser black-backed bulls (Larus fuscus), European herring gulls (L. argentatus), black-headed gulls (L. ridibundus) on landfill (Credit: Terry Whittaker/2020VISION/naturepl.com)

"To some extent pest control is not really seen as a particularly sexy subject. It can get overlooked a little," says Aonghais Cook at the British Trust for Ornithology in Thetford, Norfolk.

In a study published in 2008 while he was at Newcastle University, Cook and his colleagues explored the subject. They investigated whether falconry and other pest control measures changed the behaviour of nuisance gulls at six landfill sites across the UK.

Falconry could be effective indefinitely, as long as there is enough money to pay the falconer to return on a regular basis

His observations suggest falconry can have a useful impact, and that it may be a better long-term deterrent than some other anti-gull strategies.

Pest controllers use many gull deterrents at landfill sites, from crude methods like fireworks to more sophisticated approaches like playing seagull distress calls through loudspeakers. These methods might work for a while, but Cook and his colleagues found that over a few weeks the birds gradually realised that the threats were hollow and learned to ignore them.

But the pest birds cannot ignore a bird of prey. "A large falcon or hawk scares the birds off and keeps them off," says Cook.

In some cases, Cook found that the number of gulls on site was lower after a hawk had been used for several weeks than it was during the first few days following the introduction of the hawk. To put it another way, the predatory bird became a more effective threat with time.

In principle, it is possible that falconry could be effective indefinitely, as long as there is enough money to pay the falconer to return on a regular basis.

An Egyptian goose (Alopochen aegyptiacus) (Credit: Rod Williams/naturepl.com)

Alex Atkins of the University of Cape Town in South Africa has come to similar conclusions.

On South Africa's golf courses it is Egyptian geese that are the problem. Some golf course managers pay falconers to trundle around the fairways on golf buggies, flying Harris's hawks that spook the geese.

Falconry on its own is unlikely in most cases to solve the problem

Atkins and his colleagues decided to examine whether the approach discourages geese from lingering on the links by monitoring geese at a golf course before and during a nine-week period in which falconry was introduced. Shortly after the falconry began, goose numbers fell by about 80%, and they remained low for the rest of the monitoring period.

"We found that the presence of an avian predator was effective enough to maintain low numbers of geese on the course, provided the falconry treatment was consistent and occurred once per week," says Atkins.

The hawks occasionally caught and killed a goose, he says. This might have kept the other geese alive to the threat and prevented them from habituating to the presence of the hawks.

So the science, what little of it there is, seems to suggest that falconry works. You might well expect professional pest controllers to thoroughly endorse this conclusion. But in fact they can be far more cautious.

A Harris's hawk in Trafalgar Square, London in 2009 (Credit: EPA European Pressphoto Agency B.V./Alamy)

"Falconry on its own is unlikely in most cases to solve the problem," says David Van Vynck of Van Vynck Environmentalin Tilbury, UK, who has been in the pest control business since the 1980s.

If the hawk is not there, it has no effect

His company uses a variety of pigeon control strategies. These include falconry, but Van Vynck says the birds of prey are generally only used to deter pigeons from roosting on a given building.

"We fly a Harris's hawk an hour before the pigeons wake up naturally," says Van Vynck. "Do that for about 10 days, and by the end the pigeons are so fed up about being disturbed that they'll find somewhere else to roost."

However, in other situations – particularly when it comes to discouraging pigeons from amassing in a town centre during the day – hawks are far less likely to have a long-term impact, says Van Vynck.

"People sometimes assume that hawks leave behind a scent that will deter the pigeons and keep them away," he says. "Nothing could be further from [the] truth. If the hawk is not there, it has no effect."

When the hawk vanishes, it makes sense for the pigeons to return

When a falconer flies a hawk in a town centre, the pigeons in the area might well scatter. Just as the theory suggests, the hawk is seen as a threat and encourages the pigeons to fly away.

But within a few hours of the hawk leaving the area, the pigeons may well start to return. "You've not achieved any residual effect from what you're doing," says Van Vynck.

Oddly enough, it is probably another danger that lures the pigeons back, says ecologist Matthew Kauffman of the University of Wyoming in Laramie: not the threat of a predator, but the threat of starvation.

Pigeons (Columba livia) at the Houses of Parliament (Credit: Sam Hobson/naturepl.com)

Often, pigeons congregate in city centres because they have identified the urban jungle as a great place to forage for food. One of their biggest sources of nourishment is the waste discarded by people passing through the city.

In 1995, wolves were successfully reintroduced to Yellowstone National Park in the western US

A hungry pigeon is always looking for places where both the risk of predation and the risk of starvation are acceptably low. The sudden appearance of a hawk is enough to encourage most pigeons to look elsewhere.

But when the hawk vanishes, it makes sense for the pigeons to return.