Irruptive Migration of Bird Species

March 17, 2015 by  
Filed under Features

The main reason birds migrate is to ensure they have access to food all year round. For some bird species this may mean flying half way around the world, and their migration patterns are so predictable that birders arrange special events to welcome the weary travelers to their wintering ground, as well as to see them off when they depart. For centuries, farmers have looked to the departure and arrival of local birds as an indication of what the seasons hold, while mariners judged ocean currents and the nearness of land by the birds they encountered. Some migrating bird species are somewhat less predictable and these are referred to as irruptive migrants, with their migration habits being referred to as irruptive migration.

Some species may have a cycle of irruptive migration where they visit an area every two or four years and are therefore still predictable, while others are completely random. Reasons for irruptive migration are varied, but the most common cause is a lack of food in their normal wintering grounds. Birds that depend on birch, pine, spruce and maple seeds and catkins are known to irrupt when these trees produce poor crops. As their name suggests, crossbills have unique crossed bill-tips designed to pry conifer cones open and extract the seeds. They do not have the luxury of choosing an alternative food source and are obliged to find food they can access. As these seeds are also rodent food, if they fail to appear or produce an insufficient crop for demand, raptors may also leave the area in search of a more readily available food source.

Irrespective of what the motivating factors are for irrupting, it is virtually impossible to predict which species will irrupt in any given year and where they will migrate to, however the following species have been noted for regularly irrupting: pine siskins, bohemian waxwings, boreal chickadees, evening grosbeaks, purple finches, pine grosbeaks, common redpolls, red crossbills, white-winged crossbills, northern shrikes, hoary redpolls, red-breasted nuthatches, snowy owls, great grey owls and rough-legged hawks.

While birders generally welcome seeing unfamiliar birds at their backyard feeders, they should be aware that sometimes the unexpected visitors, particularly if they arrive in great numbers, can intimidate the locals in their quest for food. This can be overcome by setting out extra feeders and spacing them as far apart as possible. Also ensure that plenty of water is provided and water sources are cleaned regularly. Then sit back, relax, and enjoy the sight of feathered friends from far away.

Bird Atlas Tracks Trends in Britain and Ireland

December 17, 2013 by  
Filed under Features

Featuring more than 1,300 maps describing patterns of distribution for nearly 300 bird species, the new British Trust for Ornithology (BTO) Bird Atlas 2007-11 has recently been released to the public. This comprehensive study of bird distribution trends in Britain and Ireland was compiled from data gathered by more than 40,000 volunteers over a period of four summers and four winters. The information was analyzed by scientists and authors Simon Gillings, Dawn Balmer, Brian Caffrey, Bob Swann, Rob Fuller and Iain Downie and compiled into a treasure trove of information for all who are interested in the birdlife of this region.

Among the wealth of interesting information presented in the Bird Atlas is the fact that as many as forty exotic species have taken up residence in Britain and Ireland. These include the white-cheeked turaco from Ethiopia and Sudan; the red-rumped parrot of Australia; the pin-tailed whydah of sub-Saharan Africa; and the Alexandrine parakeet from Sri Lanka and India, as well as zebra finches and Chinese pheasants. While these are most likely originally escapees from private owners, they have adapted to their surroundings and many have started breeding. So, although they are not indigenous to Britain and Ireland, it appears that they are there to stay and should therefore be monitored along with local populations.

This monitoring becomes even more important when exotic species start posing a threat to native birds, as appears to be the case with the ring-necked parakeet from Delhi. These birds were first reported in the wild in Britain in 1971, having escaped from aviaries. The survey notes that there are now more than 30,000 ring-necked parakeets resident across southern Britain and they appear to be moving northwards. As they use holes in trees to lay their eggs, they are encroaching on the nesting territory of the nuthatch and other birds – and are not shy about taking over.

Observations regarding native birds include the disheartening fact that nightingales, yellowhammers and woodcocks numbers are declining. On the other hand it’s been noted that the little egret and avocet is experiencing an increase in numbers. In addition to listing statistics, the Bird Atlas provides explanations regarding changes that have taken place. For example, the decline in Dartford warbler breeding pairs from 3,214 pairs in 2006, to 600 pairs in 2010 is attributed to the harsh winters experienced in two successive years. It’s not all doom and gloom for Dartford warblers though, as the Bird Atlas notes that they have the capacity to recover and expand their range.

For more information on the new British Trust for Ornithology Bird Atlas 2007-11, visit the BTO Website.

Enjoy a Day at Birdworld in Surrey

June 5, 2012 by  
Filed under Features

Located on 26 acres in Surrey’s Alice Holt Forest, Birdworld offers the perfect setting for a family outing. As one of the largest bird parks in England, Birdworld is home to an extensive collection of bird species, housed in conditions which keep the birds happy while allowing visitors to view them up close. In addition to viewing the birds, which include everything from the tiniest Sunbird to the impressive Maribou stork, the park offers a daily program of events and activities that will keep the family busy all day.

Birdworld includes the Jenny Wren Farm with a wide range of domestic animals such as goats, pigs, ponies, chickens and a cow which visitors can pet. The pet shop at the farm has rabbits, guinea pigs, mice, ferrets, chipmunks, finches, rats and poultry. If the kids manage to persuade mom and dad that they really will look after one of these cute little creatures, the pet shop has all the housing, bedding and other paraphernalia needed to take the new member of the family home. Bird lovers will find that finches make good pets, but need to keep in mind that while they are not demanding on their owner’s time, they do need a mate, so be prepared to get two.

Daily events at Birdworld include feeding the Humboldt Penguins twice a day (11am and 3:30 pm). The keepers doing the feeding will offer interesting facts on these comical birds as they dive into the glass-sided pool for their food. Depending on weather conditions, each day between Easter and the end of October, the park has an outdoor flying display featuring a range of birds, including owls, kookaburras and parrots. The indoor Heron Theater Show stars a range of birds displaying their natural behavior while the presenter details a number of fascinating facts about these indigenous birds. Visitors can join the keepers as they feed the Owls and Bird of Prey, all the while sharing interesting facts about the birds and answering questions. The Safari Road Train takes visitors to see some of Birdworld’s larger inhabitants, including Emus, Cranes, Storks and Ostriches. Be sure to ask about the conservation projects Birdworld is involved in.

With so much to do at Birdworld, plan to spend the day at the park. You may want to try and include some of the special events, such as Art in the Park, Teddy Bear’s Picnic, or Mini Beast Safari Day, so be sure to check in with Birdworld on what’s happening when you make your plans to visit.

DNA Research Reveals Lifespan Link

January 17, 2012 by  
Filed under News

Researchers from the Universities of Exeter and Glasgow have determined in a study of the DNA of a captive population of zebra finches (Taeniopygia guttata), that just one specific piece of genetic material in a bird’s cells can reveal how long it is likely to live. Called telomeres, these portions of DNA (deoxyribonucleic acid) which mark the ends of chromosomes are found in almost all higher animals and plants. Telomeres help to protect the ends of chromosomes as they divide, preventing them from fusing with one another, or unraveling. After time, telomere ends become shorter and no longer protect chromosomes, resulting in cell damage and deterioration.

It has long been suspected that telomeres decline and the ageing process are closely linked, but this has not been proven in humans, and studies thus far have relied on limited monitoring during a lifespan. This recent study started measuring telomere length when the zebra finches were twenty-five days old and continued periodically over the course of the birds’ lives. The results, which were published this week in Proceedings of the National Academy of Sciences, revealed a close association between telomere length and longevity. Although the results in this study are very convincing, ecologist Pat Monaghan of the University of Glasgow notes that this does not necessarily hold true for humans, and telomere researcher Duncan Baird of Cardiff University agrees.

Zebra finches were chosen for the study as they breed well in captivity and have an average lifespan of nine years, allowing researchers to draw conclusions in a relatively short space of time when compared to humans, while at the same time not being as short-lived as mice. A total of ninety-nine finches were used in the study and it was noted that the association between lifespan and telomere length was strongest at twenty-five days of age. This is a time in the bird’s life when it is almost fully grown, but still sexually immature and reliant of its parents for sustenance. This age would be roughly equivalent to a prepubescent human.

More research needs to be done to determine the significance of the results, as it is known that telomere length is not exclusively genetically determined and can be shortened by stressful events. Baird also noted that the data doesn’t reveal whether telomeres are driving the ageing process. Moreover, the results were for the entire population of birds being monitored, individual results may present a different picture.