ScienceDaily (Oct. 18, 2011) — Some tropical birds collect their prey at army ant raids, where massive swarms of ants sweep through the forest and drive out insects. The behaviour of interest is called bivouac checking; it allows these birds to track the cyclical raid activity of army ant colonies.
Army ants have regular alternating periods of high and low raiding activity, and birds visit the ants' temporary nest sites (bivouacs) to determine which colonies are raiding on a given day.
The new findings published October 14 in the journal Behavioural Ecology, suggest that bivouac checking allows birds to keep track of multiple army ant colonies, keeping account of which colonies are in periods of high-raiding activity while avoiding colonies with low-raiding activity.
Recent research has discovered that birds check army ant bivouacs at the end of the day, after they have fed at the raid. They may use the information about the army ant nest location the next day to find the ants again, thus accessing a past memory (the nest location) to fulfil a future need (bird will be hungry tomorrow), also known as 'mental time-travel'.
Two of the authors of the study Corina Logan of the University of Cambridge, and Sean O'Donnell of the University of Washington, observed bivouac checking behaviour in Monteverde, Costa Rica.
Mental time-travel consists of two elements: the ability to remember past events and the ability to anticipate and plan for future events. It has traditionally been considered a quality unique to humans. However, ever since Nicola Clayton of the University of Cambridge discovered that scrub jays (a species of large-brained crow) can remember the past and plan for the future, there have been a suite of studies showing evidence of this ability in other species as well. We now know that corvids (birds in the crow family), some primates, and possibly rats have all shown the ability to remember the past and plan for the future.
Corina Logan, said: "We suspect that future planning could be involved in bivouac-checking bird behaviour because the birds were checking bivouacs when they were not hungry, a behaviour that does not make sense until the next morning upon return to the bivouac when the bird finds the ants raiding again and encounters its next meal -- a delayed benefit."
Until recently, it has been difficult to find model systems for studying mental time travel in an ecologically relevant way. "The fact that we might have happened on a whole new system for exploring these capacities is quite exciting," added Corina Logan.
http://www.sciencedaily.com/releases/2011/10/111018220938.htm
Showing posts with label army ants. Show all posts
Showing posts with label army ants. Show all posts
Wednesday, 19 October 2011
Friday, 26 November 2010
Army ants are creators not destroyers of worlds
Army ants have a reputation for annihilating everything in their path as they march through the jungle.By Matt Walker
But the most complete study of its kind has found that army ants are creators of whole worlds, not destroyers.
More than 300 species, ranging from birds to tiny mites, depend in part on a single species of army ant for their survival, scientists have discovered.
That means army ants support a greater number of other life forms than any other known species.
This revelation about army ants is the culmination of more than 50 years of scientific research into their behaviour conducted by naturalist Carl Rettenmeyer and his wife Marian, based at the University of Connecticut, US.
Together with fellow biologists, they generated a comprehensive list of animals known to be found in the company of a single army ant species Eciton burchellii.
This New World species is one of two army ant species that sends out large swarming raiding parties above ground, and it is the only one that creates temporary bivouacs above ground in piles of brush, or inside logs or tree trunks.
Around half a million worker ants belong to a colony.
Each colony sets up home for a period of 20 days, which gives time for ant pupae and newly laid eggs to develop.
During this time, the workers send out daily raids, each time proceeding in a new direction to avoid raiding the same area twice.
Then once the eggs have hatched and the larvae have become adults, the colony becomes nomadic.
During this wandering phase, the army ant colony again raids every day, setting up bivouacs at night.
But while it is well known that army ants kill and eat numerous insects and other arthropods on their raids, less well known is how many animals actually depend on the ants for their survival.
"Only a few studies have focused on collecting army ant 'guests'," says Dr Stefanie Berghoff, who worked with the Rettenmeyers to complete the study.
Some of these "guest" or associate species, as biologists call them, are already known.
So-called antbirds, for example, follow ant raiding parties, picking up arthropods flushed out by the marauding ants.
One species of African army ant even has a snake that follows it.
But until now, no-one has recognised the huge diversity of other species that army ants support.
Carl Rettenmeyer, who died in April last year, and his wife Marian started collecting these associate species in 1952.
The research team, who continued the work after Carl's death in 2009, have now collated data from 1200 coloniesof E. burchellii ants, adding samples from 345 colonies studied by other scientists.
What they found is remarkable: 557 separate species have been recorded associating with this single type of army ant.
Of those, more than 300 are known to depend on the ants in some way for their survival.
"And I think this is only the tip of the iceberg," Dr Berghoff told the BBC.
At least 29 species of bird, including "typical" antbirds, ground antbirds and woodcreepers feed on arthropods flushed out by the ants, such as millipedes, cockroaches and stick insects, rather than the ants themselves.
At least 239 butterfly species have been seen or collected at ant swarms, feeding on bird droppings laid by birds that have been attracted by the ants, while springtails run with the army ant columns at night.
Tiny wasps buzz around the ant swarms, seeking out small spiders that flee the raiding parties. These wasps are parasitoids of the spiders, laying their eggs within them.
Thousands of blowflies, flesh flies, tachinid flies and scuttle flies accompany each swarm raid too, belonging to numerous different species.
Many appear to target dead insects or those newly killed by the ants, laying their eggs within the insect carcasses.
Such species flock to each army ant raiding party, but many others frequent refuse deposits left by the ants, or the bivouacs they live in.
Army ants create refuse deposits, or garbage dumps, which contain all the hard bits of prey items, such as insects' legs, that are inedible to them and their larvae.
However, these deposits are teeming with life.
Beetle, mite, wasp and springtail species all depend on them as a habitat and food.
Tens or hundreds of similar small creatures also survive with the bivouacs of E. burchellii.
Many of these associate species are difficult to capture and study.
Because of that, say the researchers, it is likely that many, many more species that depend on E. burchellii will remain to be identified.
"If really well studied, I would think the number of E. burchellii associates could double," says Dr Berghoff.
"It is a bit of a paradox that E. burchellii, bringing death to so many species, has this other role for such a high number of associates," she adds.
Editor, Earth News
http://news.bbc.co.uk/earth/hi/earth_news/newsid_9209000/9209345.stm
But the most complete study of its kind has found that army ants are creators of whole worlds, not destroyers.
More than 300 species, ranging from birds to tiny mites, depend in part on a single species of army ant for their survival, scientists have discovered.
That means army ants support a greater number of other life forms than any other known species.
This revelation about army ants is the culmination of more than 50 years of scientific research into their behaviour conducted by naturalist Carl Rettenmeyer and his wife Marian, based at the University of Connecticut, US.
Together with fellow biologists, they generated a comprehensive list of animals known to be found in the company of a single army ant species Eciton burchellii.
This New World species is one of two army ant species that sends out large swarming raiding parties above ground, and it is the only one that creates temporary bivouacs above ground in piles of brush, or inside logs or tree trunks.
Around half a million worker ants belong to a colony.
Each colony sets up home for a period of 20 days, which gives time for ant pupae and newly laid eggs to develop.
During this time, the workers send out daily raids, each time proceeding in a new direction to avoid raiding the same area twice.
Then once the eggs have hatched and the larvae have become adults, the colony becomes nomadic.
During this wandering phase, the army ant colony again raids every day, setting up bivouacs at night.
But while it is well known that army ants kill and eat numerous insects and other arthropods on their raids, less well known is how many animals actually depend on the ants for their survival.
"Only a few studies have focused on collecting army ant 'guests'," says Dr Stefanie Berghoff, who worked with the Rettenmeyers to complete the study.
Some of these "guest" or associate species, as biologists call them, are already known.
So-called antbirds, for example, follow ant raiding parties, picking up arthropods flushed out by the marauding ants.
One species of African army ant even has a snake that follows it.
But until now, no-one has recognised the huge diversity of other species that army ants support.
Carl Rettenmeyer, who died in April last year, and his wife Marian started collecting these associate species in 1952.
The research team, who continued the work after Carl's death in 2009, have now collated data from 1200 coloniesof E. burchellii ants, adding samples from 345 colonies studied by other scientists.
What they found is remarkable: 557 separate species have been recorded associating with this single type of army ant.
Of those, more than 300 are known to depend on the ants in some way for their survival.
"And I think this is only the tip of the iceberg," Dr Berghoff told the BBC.
At least 29 species of bird, including "typical" antbirds, ground antbirds and woodcreepers feed on arthropods flushed out by the ants, such as millipedes, cockroaches and stick insects, rather than the ants themselves.
At least 239 butterfly species have been seen or collected at ant swarms, feeding on bird droppings laid by birds that have been attracted by the ants, while springtails run with the army ant columns at night.
Tiny wasps buzz around the ant swarms, seeking out small spiders that flee the raiding parties. These wasps are parasitoids of the spiders, laying their eggs within them.
Thousands of blowflies, flesh flies, tachinid flies and scuttle flies accompany each swarm raid too, belonging to numerous different species.
Many appear to target dead insects or those newly killed by the ants, laying their eggs within the insect carcasses.
Such species flock to each army ant raiding party, but many others frequent refuse deposits left by the ants, or the bivouacs they live in.
Army ants create refuse deposits, or garbage dumps, which contain all the hard bits of prey items, such as insects' legs, that are inedible to them and their larvae.
However, these deposits are teeming with life.
Beetle, mite, wasp and springtail species all depend on them as a habitat and food.
Tens or hundreds of similar small creatures also survive with the bivouacs of E. burchellii.
Many of these associate species are difficult to capture and study.
Because of that, say the researchers, it is likely that many, many more species that depend on E. burchellii will remain to be identified.
"If really well studied, I would think the number of E. burchellii associates could double," says Dr Berghoff.
"It is a bit of a paradox that E. burchellii, bringing death to so many species, has this other role for such a high number of associates," she adds.
Editor, Earth News
http://news.bbc.co.uk/earth/hi/earth_news/newsid_9209000/9209345.stm
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