Of Bears and Berries: Return of Wolves Aids Grizzly Bears in Yellowstone

July 29, 2013 — A new study suggests that the return of wolves to Yellowstone National Park is beginning to bring back a key part of the diet of grizzly bears that has been missing for much of the past century -- berries that help bears put on fat before going into hibernation.

It's one of the first reports to identify the interactions between these large, important predators, based on complex ecological processes. It was published today by scientists from Oregon State University and Washington State University in the Journal of Animal Ecology.

The researchers found that the level of berries consumed by Yellowstone grizzlies is significantly higher now that shrubs are starting to recover following the re-introduction of wolves, which have reduced over-browsing by elk herds. The berry bushes also produce flowers of value to pollinators like butterflies, insects and hummingbirds; food for other small and large mammals; and special benefits to birds.

The report said that berries may be sufficiently important to grizzly bear diet and health that they could be considered in legal disputes -- as is white pine nut availability now -- about whether or not to change the "threatened" status of grizzly bears under the Endangered Species Act.

Read further

Birds and berries to be surveyed

Gardeners and birdwatchers are being asked to help identify birds' berry-eating habits.

The British Trust for Ornithology (BTO) study is the first large study of how birds use garden berries and fruits.

While it is known that berries attract birds, little is understood about which berries different bird species favour.

Scientists are concerned that by preferring certain berries, birds may be spreading the seeds of invasive plant species, such as cotoneaster.

The bounty of berries that autumn and winter produce can be an important source of food for many birds, such as thrushes, starlings and wintering warblers.

They offer sugars and easily digestible nutrients during a time when food can be scarce.

The plants that produce the berries then rely on the birds to disperse the seeds hidden within this nutritious flesh.

Garden berries are important as they are usually available later in the year and often untouched by other birds.

The mistle thrush will aggressively defend holly berries all winter, for example.

But little is actually known about which garden berries and fruits are being eaten by which birds and when.

"There is no evidence for how important garden berries are compared to those in the wider countryside," said Mike Toms, head of garden ecology at the BTO.

Read on:  http://www.bbc.co.uk/nature/19422637