Increased predator numbers in Yellowstone changing elk migration patterns

Migration no longer best strategy for Yellowstone elk herd

June 2013. Migratory elk are returning from Yellowstone National Park with fewer calves due to drought and increased numbers of big predators - two landscape-level changes that are reducing the benefits of migration with broader implications for conservation of migratory animals, according to a new study published in the journal Ecology.

Long-term decline in the number of calves in migratory elk

The new study by the Wyoming Cooperative Fish and Wildlife Research Unit - a joint program involving U.S. Geological Survey, the University of Wyoming, and the Wyoming Game and Fish Department, describes a long-term decline in the number of calves produced annually by the Clarks Fork herd, a population of about 4000 elk whose migrants travel annually between winter ranges near Cody, Wyoming and summer ranges within Yellowstone National Park. Migratory elk experienced a 19 percent depression in rates of pregnancy over the four years of the study and a 70 percent decline in calf production over 21 years of monitoring by the WGFD, while the elk that did not migrate, known as resident elk, in the same herd experienced high pregnancy and calf production and are expanding their numbers and range into private lands outside of the park.

Ungulates still retain their long-distance seasonal migrations

"This is one of North America's wildest and best-protected landscapes, where elk and other ungulates still retain their long-distance seasonal migrations - and yet it is the migratory elk that are struggling while their resident counterparts thrive in the foothills," said Arthur Middleton, who led this work as a University of Wyoming doctoral student and is now a postdoctoral fellow at the Yale School of Forestry and Environmental Studies.

Continued

What is killing off our farmland birds – loss of habitat or a rise in predators?

Even the wildest areas of the British Isles are managed by man. We intervene in nature at so many levels, from directly controlling some wild species, through culling or special protection, to introducing domestic stock and taming wild areas for food production. And we have done so for thousands of years. There are often unintended consequences from such intensive management, creating ideal circumstances for some species to thrive and squeezing others out. That means intervening again, to adjust the numbers that have been artificially boosted by our behaviour or give a helping hand to those we have inadvertently caused to decline.

Numerous scientific studies have sought to show why farmland birds – much loved by millions of people – have suffered such serious declines in the past half-century. For some of the most vulnerable species, numbers are down by 80 per cent or more.

The traditional view, promoted by a range of wildlife charities, is that intensive farming, which grubbed up hedgerows and sprayed insect and weed-killing chemicals around through the late-1960s and 1970s, was the culprit.

Yet we have now had several decades of reversing those habitat losses – planting new hedgerows and restoring those that remained; planting woodland and incorporating wild flower field margins with all-important seed-producing plants into arable land. Many millions in grant aid, from the European Union and the British Government, all paid for by UK taxpayers, has been invested in various projects.

Yet, as surveys repeatedly tell us, the declines for the most part continue. It is not a uniformly gloomy picture, by any means, but it is fair to say that, in spite of the best efforts of farmers and environmentalists, the medicine is not working as many would like.

Some studies suggest the changes made to farming practices have not yet taken effect or are not radical enough. Ian Newton, writing in Ibis, the international journal of avian science, concluded in an exhaustive report in 2004 that more time would be needed for the positive effects to be felt.

He wrote: "Although it is too early to assess properly the effects of recently introduced agri-environment schemes, earlier schemes were most successful when targeted to the needs of particular species, such as cirl bunting, lapwing, stone curlew and corncrake, and of some seed-eaters through winter seed provision."

Read on:  http://www.thisiscornwall.co.uk/killing-farmland-birds-ndash-loss-habitat-rise/story-16321467-detail/story.html