Great tits eating bats


From New Scientist:

Killer birds bite off bats’ heads

* 00:00 09 September 2009 by Sanjida O’Connell

It sounds like the avian equivalent of an Ozzy Osbourne legend. Great tits have been discovered killing and eating bats by pecking their heads open.

Although bats have been reported preying on songbirds before, this is the first time great tits have been observed to prey on bats.

Péter Estók of the Max-Planck-Institute for Ornithology, Germany, first saw a bat being captured by a tit in a Hungarian cave in 1996.

Ten years later, he and fellow bat ecologist Björn Siemers recorded 18 examples of pipistrelle bat predation by great tits, over the course of two winters in the same cave in the Bükk Mountains.

Bat hunting

The birds seek out bats as they wake from hibernation and usually eat them in the cave, though sometimes they carry them to a nearby tree.

“The birds don’t kill the bats before they start eating them,” says Siemers, “but the bats eventually die when the birds peck open their brain case.”

As the bats are still very cold, only a degree above ambient temperature, they are extremely slow and easy for the birds to subdue. Nevertheless, it is a considerable feat for the tits given that a pipistrelle weighs approximately 5 grams and a great tit only four times as much.

Sly birds

The scientists ran an experiment to supply the tits with food, and discovered that this reduced consumption.

“This shows that the birds are predating the bats for food in times of scarcity. It shows how inventive this species can be,” says Siemers.

Estók and Siemers also ran a playback experiment where they recorded and played the calls that the bats made as they woke from hibernation. The great tits were attracted to the calls.

“For a bat, these calls are very low frequency, a maximum of 15 kiloHertz, but at a high frequency for the tits, above scientifically established hearing levels for this species, yet they react to them,” says Siemers.

Who started it?

Gareth Jones, an expert on bat behaviour at the University of Bristol, says the finding is unexpected and novel. “I don’t know of any other studies of predation of hibernating bats by small birds. It’s a big jump for the tits, given that their normal prey are caterpillars.”

As the birds have been anecdotally observed to eat bats in this cave for a decade, Siemers speculates that this is an example of cultural transmission. There are also four anecdotal reports of bats being eaten by tits in Sweden and Poland.

Jones says, “Presumably this is learned behaviour, but it is much too strong an inference to suggest that it could be culturally transmitted from Poland to Hungary.”

See also here. And here.

Thanks to Ville Sinkkonen, I’ve just learnt of this Finnish news article: it reports wildlife photographer Lassi Kujala’s discovery of more than ten Common redpolls Carduelis flammea killed by Great tits Parus major. A Yellowhammer Emberiza citrinella was killed as well: here.

Scientists find successful way to reduce bat deaths at wind turbines: here.

Biologists for the first time have documented a second breeding season during the annual cycle of five songbird species that spend summers in temperate North America and winters in tropical Central and South America: here.

March 2010. In the biggest ever analysis of songbirds and their predators, published in the Journal of Applied Ecology, scientists look at the role of predators in the decline of species such as Bullfinch and Yellowhammer. Whilst a small number of associations may suggest significant negative effects between predator and prey species, for the majority of the songbird species examined there is no evidence that increases in common avian predators or Grey squirrels are associated with large-scale population declines: here.

Over 1,300 new species discovered in Australia


From the Irish Times:

Flesh-eating plant and a fast-talking frog among Australian discoveries

PÃDRAIG COLLINS in Sydney

A FLESH-EATING plant, the fast-talking tree frog and one of the world’s most venomous snakes are among at least 1,300 new plant and animal species discovered in Australia over the past decade, according to a new report from the World Wildlife Federation.

The report highlights the discovery of over a thousand plants, 195 fish, 74 reptiles, 13 amphibians and seven mammals. “The extent of Australia’s rich biodiversity is astounding,” said Michael Roache, threatened species programme manager of WWF-Australia.

“This report shows that we have discovered an average of at least two new species a week every year for the past 10 years . . . But this could just be the tip of the iceberg. There could be thousands more out there.”

Mr Roache says the fast-talking tree frog is not even the most interesting frog discovered. “It’s just got a very fast, trilling call,” he told The Irish Times. “The name sounds cooler than the species might be.

“A more interesting discovery is the northern stony-creek frog. The males and females are brown for most of the year, but males turn yellow during breeding season.

“He then turns bright yellow when coupling with the female. It’s a good thing humans don’t do that,” said Mr Roache.

While flesh-eating plants have a long history as B-movie staples, the Nepenthes tenax, better known as the pitcher plant, was only discovered in 2006 in Cape York, far north Queensland. It can grow up to one metre tall – far greater than the usual 15cm limit for such plants – and has a taste for small rats, mice, lizards and even birds.

Of more immediate concern to humans is the newly-discovered central ranges Taipan, believed to be one of the world’s most venomous snakes. As well as presenting strange and exotic new flora and faunae to the world, the report says many vital habitats are increasingly endangered.

“Over 1,700 of Australia’s plants and animals are listed by the Australian government as threatened. With the discovery of so many new and exciting species it is crucial that efforts to keep them off the threatened lists are maintained,” said Mr Roache.

One of Australia’s most endangered species, the pipistrelle bat of Christmas Island, may have just become extinct.

Scientists have spent a month trying to capture the bats for a breeding programme, but have failed to find any.

White ibis becoming urban birds in Australia due to drought: here.

Seasonal population dynamics of the Australian White Ibis (Threskiornis molucca) in urban environments: here.

Our knowledge of Australian bat taxonomy is roughly at the stage of American bat taxonomy 100 years ago. It’s not that our Aussie mammal taxonomists have been out to lunch, but Australia has a shorter history of European settlement than the USA, and a smaller population, and we have at least twice as many bat species to sort out: here.