Wandering Tattler - February 2009.pdf - Nature Vancouver

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NATURAL SELECTION GIVES WAY TO HUMAN SELECTION PRACTICE OF HUNTING AND HARVESTING THE BIGGEST ANIMALS OR PLANTS IS CHANGING SPECIES MUCH FASTER THAN NATURE, RESEARCHERS FIND Humans have become "super predators," speeding up the evolution of the species they hunt and harvest at rates far above what is found in nature, according to new research, some of it conducted by Canadian biologists. The researchers believe that many recently observed changes in species, ranging from the shrinkage in the horns of bighorn sheep in the Rockies to the reduction in the size of caribou in Scandinavia, are being driven by humans. 4 The biologists estimate that hunting has caused such characteristics as body size and reproductive age to change at a rate that is a staggering 300 per cent above the pace that would prevail in nature. This figure is even greater than the change attributed to other human interferences, such as pollution, which was estimated to alter species 50 per cent faster than what normally happens. "The implications are pretty wide and profound," said Paul Paquet, a University of Calgary biologist who dubs humans "super predators" for this outsized impact. A paper outlining the findings was posted yesterday in the online edition of Proceedings of the National Academy of Sciences. In it, Dr. Paquet and others argue that current hunting and harvesting practices are inadvertently causing dramatic changes in the behaviour and appearance of species. The reason: Humans tend to "high-grade" nature, taking out the biggest and best in a species. The approach is clearest in trophy hunting, where animals with the biggest horns or bodies are killed, while inferior ones are left. But the practice also occurs in commercial fishing, where mesh openings in nets capture the biggest fish while smaller ones escape. The human approach is the opposite to what happens in nature, where predators kill the easiest-to-catch animals, such as the young, the old and the sick, but are unable to take out the fittest adults, which then reproduce and pass their desirable characteristics on to future generations. Many hunting rules are based on a view that bagging mature animals is the best approach, but Dr. Paquet says humans should be trying to emulate nature, even though at first glance it doesn't seem sporting to kill younger creatures. "That's clearly the best management regime," he said. The researchers, who are affiliated with the University of Calgary and the University of Victoria as well as two U.S. universities, looked at 34 studies that examined physical or biological characteristics in 29 species subject to heavy pressure from human predation. Besides the bighorn sheep and caribou, they included snails; a pair of medicinal plants; and various commercially caught fish. "Harvested organisms are the fastest-changing organisms of their kind in the wild because we are super predators and we take such high proportions of a population and target the largest individuals," Dr. Paquet said. The rate of change is staggering from an evolutionary point of view, where the alteration in species is often thought to occur slowly. Alberta's bighorn sheep, for instance, have experienced a 20-per-cent drop in the length and size of their horns in only the past 30 years. The sheep are prized for the distinctive curve in their horns, making them sought-after trophies. Atlantic cod, whose populations have collapsed because of over fishing, now reproduce at an average age of five years, rather than six, as was the case previously. The change, which in humans would amount to children reaching sexual maturity and having offspring at ages of around nine to 11, occurred in only two decades. Among the species harvested or hunted by humans and reviewed in the paper, body size or horn size decreased by an average 18 per cent. There was also a pattern of reproduction at an earlier age or smaller size. THE DIMINISHING PREY BIGHORN SHEEP The sheep, found in mountainous areas of Western Canada and the United States, are famed for the unusual curved horns on the rams. The rams are hunted as trophies, but researchers believe the practice of taking the biggest specimens has prompted genetic change leading to a marked decline in horn size. CARIBOU Caribou from southern Norway, the last remaining wild population in Europe, have shrunk because of hunting. The selective killing of the biggest animals has led to a reduction in the size of bodies, antlers and jaws. Researchers suspect the same trend may have occurred in southern populations of caribou in Canada. AMERICAN GINSENG The gnarled root of the plant is prized for its medicinal properties - collected for illnesses ranging from cancer to Alzheimer's disease. But extensive harvesting has led to a change in the composition of wild stands, with an increased number of smaller, nonreproductive plants. COD The destruction of cod stocks has led to altered reproductive behaviour. The fish produce eggs at a younger age, but this early breeding has a big drawback. The early breeders are producing abnormally low numbers of eggs. Martin Mittelstaedt From Globe and Mail January 13, 2009 The Wandering Tattler February 2009 page 10
THE 2008 LADNER CHRISTMAS BIRD COUNT RESULTS The 2008 Ladner CBC – originally set for December 21, was rescheduled to January 4 due to heavy snowfall and bad road conditions. While the January day wasn’t too bad, a cold, heavy wind did come up in the afternoon, and then it started snowing - big time - while we were doing the post count tally and dinner. We quickly finished up and got the birder’s heading home before the roads were too dangerous. A total of 133 species were seen on count day, plus 2 species within count period. Our highlights included: a Mountain Chickadee and several Anna’s Hummingbirds which were seen at feeders in Delta: a White-throated Sparrow seen near the Vancouver Landfill. If anyone would like an electronic version of the final count tally please contact judegrass@shaw.ca. Thank you to the BC Waterfowl Society for the use of the museum for the post count gathering and to John Ireland for his assistance on count day. ATTENTION RAPTOR FANS…. Jude Grass Ladner CBC Coordinator A wonderful article describing the Harlan’s Hawk has been published in the current edition of Birding the American Birding Association magazine. You can find a pdf version of the article and additional information that was not part of the printed article at the following website. The article is a must read for those who are interested in identifying Harlan’s Hawk and Red-tailed Hawks. The link is: http://aba.org/birding/v41n1p30.pdf Authored by William (Bill) Clark, who recently gave two very successful Raptor Identification courses sponsored by the Birding Section of Nature Vancouver we were actually fortunately enough to confirm a Harlan’s Hawk at McDonald Slough on Sea Island on one of the course field trips. The Stanley Park Heronry The Stanley Park Ecology Society is monitoring the heron nesting sites in Stanley Park for several organizations and studies. The provincial government’s Ministry of Environment is conducting research to determine the impact of predators and human interaction on nesting great blue herons. The data will also be forwarded to Bird Studies Canada to contribute to their national study of nesting habits and trends. See the: http://www.stanleyparkecology.ca/programs/conservation /urbanWildlife/herons/ to read the reports: 1. Stanley Park Heron Colony Final Report 2008 2. UBC Heron Colony 2008 Nesting Report WILD BIRDS UNLIMITED MONTHLY WALKS The following walks are offered by the Wild Bird Stores in Vancouver and North Vancouver. The next walk is Saturday February 21 to Jericho Park starting at 10 a.m. Meet in the parking lot at the west end of the park near the washroom buildings. Walks last approximately 2 hours. Bring your binoculars if you have them. For more details phone 604-736-2676. The Wandering Tattler February 2009 page 11
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Wandering Tattler - February 2009.pdf - Nature Vancouver

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