El Gentraso has rashly signed up to participate in Just Science. That means there'll be something new and science-related every day here Monday through Friday next week.
Equally rashly, I'll be hosting the March edition of Oekologie, the new ecology blogging carnival. It'll be just like real carnival, except without the samba bands and cross-dressing.
Meanwhile, in the real world, I'm speaking at the Edinburgh Science Festival on 9 April (easter Monday), talking about ITBOAH at 6 p.m. in the National Museum of Scotland's Lecture Theatre. And on 18 April I'm speaking about D'Arcy Wentworth Thompson at the Royal Institution in London. Except it'll be in the Royal College of Surgeons, because the RI's building is being done up. This is part of a series of RI events on polymaths.
Wednesday, January 31, 2007
Monday, January 29, 2007
Sleep and metabolic rate
Update: the link to the paper is now working. Duh. Sorry.
Sleep is another of those biological phenomena of which we lack a good theoretical understanding, despite there being lots and lots of (good) hypotheses and experiments. Van Savage and Geoff West have suggested a first step to building one, though. And (wouldn't you know it) it's based around metabolic rate.
The amount of time a mammal spends asleep, they find, is proportional to their relative, or cellular, metabolic rate. A fast-burner like a mouse sleeps for about 14 hours a day, whereas an elephant kips for only 3.5 hours. What's cool is that they find that sleep time is most closely matched to the brain's metabolic rate. Their suggestion is that sleep duration corresponds to the amount of time needed either repair brain cells, or reorganize them to process the day's input.
So unlike other organs, perhaps you need to shut down the (conscious) brain to maintain it. Fast-celled animals need more time for repairs (which, if this model holds, seems a more likely function of sleep - or at least of metabolically related sleep - than reorganization), because they do more damage while they're awake. The same argument applies to why small animals have shorter lifespans - fast cells, more free-radical damage, shorter lives.
What's that Lassie? A lot in life seems to depend on metabolic rate? Perhaps by understanding metabolic rate we can inch towards some kind of powerful, simple theory to explain a wide range of biology? You wish someone had written an accessible guide to this vibrant field and its long and strange history? Well, girl, it's your lucky day.
Sleep is another of those biological phenomena of which we lack a good theoretical understanding, despite there being lots and lots of (good) hypotheses and experiments. Van Savage and Geoff West have suggested a first step to building one, though. And (wouldn't you know it) it's based around metabolic rate.
The amount of time a mammal spends asleep, they find, is proportional to their relative, or cellular, metabolic rate. A fast-burner like a mouse sleeps for about 14 hours a day, whereas an elephant kips for only 3.5 hours. What's cool is that they find that sleep time is most closely matched to the brain's metabolic rate. Their suggestion is that sleep duration corresponds to the amount of time needed either repair brain cells, or reorganize them to process the day's input.
So unlike other organs, perhaps you need to shut down the (conscious) brain to maintain it. Fast-celled animals need more time for repairs (which, if this model holds, seems a more likely function of sleep - or at least of metabolically related sleep - than reorganization), because they do more damage while they're awake. The same argument applies to why small animals have shorter lifespans - fast cells, more free-radical damage, shorter lives.
What's that Lassie? A lot in life seems to depend on metabolic rate? Perhaps by understanding metabolic rate we can inch towards some kind of powerful, simple theory to explain a wide range of biology? You wish someone had written an accessible guide to this vibrant field and its long and strange history? Well, girl, it's your lucky day.
Wednesday, January 24, 2007
My new £16,000 habit
Winter finally came to London today, with a couple of inches of snow falling overnight. It was a nice surprise to wake up to. And not before time: we were hiking in the Peak District over new year, and you barely needed a coat, it was so warm (although the waterproof properties of goretex did come in handy, I admit). Woodland birds were singing, the odd tree was in blossom, and a friend in London has seen bumble bees in her garden. Anyway, enjoy the winter walking before the flood waters rise to engulf us all.
While in Derbyshire, we happened upon the excellent Hawkridge books in Castleton. They have a huge collection nature books, especially ornithology, and also good sections on climbing, mountaineering, etc.
In particular, they major in the Collin's New Naturalist series. This was set up during the second world war by, among others, Julian Huxley (who also popularized the use of allometry, thus earning himself a cameo in ITBOAH), with the intention of educating laypeople about the natural world.
Recently, the books have become collectors' items. The 100th in the series, 'Woodlands' by the legendary Oliver Rackham was published recently. There have also been other off-series monographs, so a complete set numbers around 120 books. The extremely nice man at Hawkridge told us that a set recently went at auction for £16,000 (about $32,000). The Woodlands book also exists in a limited edition, leather-bound version that is already changing hands for hundreds of pounds, apparently. The two rarest, nos. 70 Orkney and 71 Warblers (both from 1985) thanks to their extremely short print runs, are worth thousands. There's an extremely nice article about the whole thing here.
The NN clearly owe their value to a perfect storm of British male nerdiness - we, and especially amateur naturalists, love collecting, making lists, getting the complete set. So something that appeals to both naturalists and book collectors is bound to do well. They are also lovely books, with instantly recognizable covers.
Anyway,I'm not given to impulse purchases (although I'm quite partial to Nonesuch Explorer recordings on vinyl), but Hawkridge had a first edition of NN number 3, London's Natural History by Richard Fitter (with pictures by Eric Hosking, published in 1945 that they were selling for only £8. As a Londonist, this was clearly too good to miss, even though I had to carry it for several more days' walking. Only 102 (they're up to 103 now) to go.
While in Derbyshire, we happened upon the excellent Hawkridge books in Castleton. They have a huge collection nature books, especially ornithology, and also good sections on climbing, mountaineering, etc.
In particular, they major in the Collin's New Naturalist series. This was set up during the second world war by, among others, Julian Huxley (who also popularized the use of allometry, thus earning himself a cameo in ITBOAH), with the intention of educating laypeople about the natural world.
Recently, the books have become collectors' items. The 100th in the series, 'Woodlands' by the legendary Oliver Rackham was published recently. There have also been other off-series monographs, so a complete set numbers around 120 books. The extremely nice man at Hawkridge told us that a set recently went at auction for £16,000 (about $32,000). The Woodlands book also exists in a limited edition, leather-bound version that is already changing hands for hundreds of pounds, apparently. The two rarest, nos. 70 Orkney and 71 Warblers (both from 1985) thanks to their extremely short print runs, are worth thousands. There's an extremely nice article about the whole thing here.
The NN clearly owe their value to a perfect storm of British male nerdiness - we, and especially amateur naturalists, love collecting, making lists, getting the complete set. So something that appeals to both naturalists and book collectors is bound to do well. They are also lovely books, with instantly recognizable covers.
Anyway,I'm not given to impulse purchases (although I'm quite partial to Nonesuch Explorer recordings on vinyl), but Hawkridge had a first edition of NN number 3, London's Natural History by Richard Fitter (with pictures by Eric Hosking, published in 1945 that they were selling for only £8. As a Londonist, this was clearly too good to miss, even though I had to carry it for several more days' walking. Only 102 (they're up to 103 now) to go.
Tuesday, January 23, 2007
How many pictures of leopards does the world need?
We went to the (staggeringly busy) Natural History Museum on Sunday, to see the Wildlife Photographer of the year exhibition. I've been coming to this for 20 years or more now. Usually I ooh and aah at the lovely pictures, and go away saying to myself it's a wonderful world. But this year, for some reason, I didn't react like that (or anyway, not just like that).
Here then, in no particular order, is the case against wildlife photography — or at least the vision of the natural world presented by this competition — that I found myself making as I walked round the show:
The same things seem to come back year after year — comical penguins, majestic birds of prey, big cats, cute baby animals. All set against atmospheric backdrops of sunsets, sunrises, snow, clouds of dust, and so on. It's a fine line between naff and beautiful.
Interestingly, the pictures that win the big prize tend not to be like this — more often, they are impressionistic (which I don't like, because they seem to be trying to imitate painting, which misses the point) or abstract, such as this year's winner, of a walrus, or last year's (which I think is an exciting and original image), of a peregrine attacking some starlings.
Does, and can, wildlife photography develop and change — like, say, portrait photography does. Obviously equipment gets better, but do the genre's aesthetics develop? Not much, would be my suspicion. There seems to be a very narrow version of what's beautiful and impressive about wildlife, that doesn't have a place for anything scary, or horrific (does anyone photograph parasitoids eating their way out of caterpillars?), or strange. Yet, let's face it, nature can be all of these things, and they are meat and drink to other forms of visual art.
The feeling that nature was being boiled down to a series of money shots also came to me while watching the BBC's Planet Earth series which, although it had some staggering images, and showed me lots of stuff I never new existed, lacked the narrative and scientific integrity of David Attenborough's various 'Life' series. Basically, the message was: 'Look at that! And that!'
(If Planet Earth was anything to go by, one thing that has changed in wildlife TV is that filmmakers are much less keen to show the violence that's often thought to be a staple of the genre — usually, the hunt was shown, but we cut off to somewhere else before the kill. This is probably a mixture of Good Taste, and a sense that this sort of thing is getting clichéd. Similarly, in the still photos there was no blood, or shagging.)
Such a highlights-reel approach commodifies nature. These photos blend seamlessly into the high-gloss adverts that surround and tempt us, and a lot of these pictures wouldn't have looked out of place in Condé Nast Traveller, say, or an advert for wide-screen television.
It also exoticizes nature, making it something that happens elsewhere. There's a category for urban wildlife, but it's weak, and this year's winning photo was of that noted urban species, the grizzly bear, pictured on that noted metropolis, the Kamchatka Peninsula. The risk is that we'll think of wildlife as something glossy, impressive, and expensive, not as all the stuff that surrounds us, and is worth checking out and looking after.
You can't blame photographers and exhibitors for this — folks wouldn't queue up to look at a whole roomful of pictures of starlings. But I would applaud the wildlife photographer who actually tried to capture the real experience of watching wildlife, rather than an idealized freeze-frame of wildlife. Usually, this involves a brief glimpse of something's arse as it scuttles into the undergrowth, or squinting at a distant silhouette. But such views are much more satisfying, because they're real, and because we have got them ourselves. Where's the Martin Parr of wildlife photos?
Here then, in no particular order, is the case against wildlife photography — or at least the vision of the natural world presented by this competition — that I found myself making as I walked round the show:
The same things seem to come back year after year — comical penguins, majestic birds of prey, big cats, cute baby animals. All set against atmospheric backdrops of sunsets, sunrises, snow, clouds of dust, and so on. It's a fine line between naff and beautiful.
Interestingly, the pictures that win the big prize tend not to be like this — more often, they are impressionistic (which I don't like, because they seem to be trying to imitate painting, which misses the point) or abstract, such as this year's winner, of a walrus, or last year's (which I think is an exciting and original image), of a peregrine attacking some starlings.
Does, and can, wildlife photography develop and change — like, say, portrait photography does. Obviously equipment gets better, but do the genre's aesthetics develop? Not much, would be my suspicion. There seems to be a very narrow version of what's beautiful and impressive about wildlife, that doesn't have a place for anything scary, or horrific (does anyone photograph parasitoids eating their way out of caterpillars?), or strange. Yet, let's face it, nature can be all of these things, and they are meat and drink to other forms of visual art.
The feeling that nature was being boiled down to a series of money shots also came to me while watching the BBC's Planet Earth series which, although it had some staggering images, and showed me lots of stuff I never new existed, lacked the narrative and scientific integrity of David Attenborough's various 'Life' series. Basically, the message was: 'Look at that! And that!'
(If Planet Earth was anything to go by, one thing that has changed in wildlife TV is that filmmakers are much less keen to show the violence that's often thought to be a staple of the genre — usually, the hunt was shown, but we cut off to somewhere else before the kill. This is probably a mixture of Good Taste, and a sense that this sort of thing is getting clichéd. Similarly, in the still photos there was no blood, or shagging.)
Such a highlights-reel approach commodifies nature. These photos blend seamlessly into the high-gloss adverts that surround and tempt us, and a lot of these pictures wouldn't have looked out of place in Condé Nast Traveller, say, or an advert for wide-screen television.
It also exoticizes nature, making it something that happens elsewhere. There's a category for urban wildlife, but it's weak, and this year's winning photo was of that noted urban species, the grizzly bear, pictured on that noted metropolis, the Kamchatka Peninsula. The risk is that we'll think of wildlife as something glossy, impressive, and expensive, not as all the stuff that surrounds us, and is worth checking out and looking after.
You can't blame photographers and exhibitors for this — folks wouldn't queue up to look at a whole roomful of pictures of starlings. But I would applaud the wildlife photographer who actually tried to capture the real experience of watching wildlife, rather than an idealized freeze-frame of wildlife. Usually, this involves a brief glimpse of something's arse as it scuttles into the undergrowth, or squinting at a distant silhouette. But such views are much more satisfying, because they're real, and because we have got them ourselves. Where's the Martin Parr of wildlife photos?
Thursday, January 18, 2007
Feed the trees
How good are forests at soaking up carbon, and how much will they buffer greenhouse gas emissions and save us from climate change?
It's an extremely knotty question — and so this review (open access) of the issue just published in New Phytologist is extremely welcome. Increased CO2 should be a fertilizer, and things grow quicker in warm weather, but as temperature increases, the rate of respiration rises more quickly than the rate of photosynthesis, so the rate at which trees release more carbon rises more quickly than the rate at which they soak it up (this also has implications for metabolic ecology: by understanding these effects, via metabolic rate, you can build a bridge between cellular and individual metabolism and the workings of the global carbon cycle). Also, plant growth is limited by other things, so a lack of nitrogen, for example, may limit trees' ability to respond to higher CO2, or warmer temperatures.
The review, which looks at studies in boreal and temperate forests, concludes that we don't really know what's going to happen. Here's what they say…
This seems a good argument against tree-planting carbon offset schemes.
It's an extremely knotty question — and so this review (open access) of the issue just published in New Phytologist is extremely welcome. Increased CO2 should be a fertilizer, and things grow quicker in warm weather, but as temperature increases, the rate of respiration rises more quickly than the rate of photosynthesis, so the rate at which trees release more carbon rises more quickly than the rate at which they soak it up (this also has implications for metabolic ecology: by understanding these effects, via metabolic rate, you can build a bridge between cellular and individual metabolism and the workings of the global carbon cycle). Also, plant growth is limited by other things, so a lack of nitrogen, for example, may limit trees' ability to respond to higher CO2, or warmer temperatures.
The review, which looks at studies in boreal and temperate forests, concludes that we don't really know what's going to happen. Here's what they say…
It is not in doubt that newly established young forests will continue to be C sinks for the foreseeable future. The key question is whether the mature forests that are C sinks today will continue to be sinks as the climate changes. … Forest ecosystem models indicate that the additional terrestrial sink arising from global climate change is likely to be maintained in the short term (over several decades), but may gradually diminish in the medium term. … Because of current limitations on our understanding with respect to acclimation of the physiological processes, the climatic constraints, and feedbacks among these processes – particularly those acting at the biome scale – projections of C-sink strengths beyond a few decades are highly uncertain.
This seems a good argument against tree-planting carbon offset schemes.
Tuesday, January 16, 2007
How big can a meat-eater get?
Today's news@nature has a story by me (free for a week) about an extremely ITBOAH-esque paper on carnivore energetics and ecology by Chris Carbone and colleagues. This looks at the costs and benefits of different hunting strategies — basically, whether you eat stuff much smaller than you (as tends to be the case with small carnivores, such as hedgehogs), or whether you try and bring down things about your own size (which is what big carnivores such as cheetahs and wolves tend to do).
Eating small stuff is a cheap, low-return strategy, unable to support big carnivores — this limits the maximum size of insectivores. Eating big stuff is high return, but costly, because hunting takes a lot of energy. And it becomes more costly the bigger you get — until at about 1,100 kg, carnivores go out of business.
The largest fossil carnivores are about this size. It also suggests how evolution might paint carnivores into a corner — being big and fierce has obvious advantages, in that you're a top hunter, and you can boss your own species about. But in hard times, you starve. The fossil record seems to show high turnover for fossil carnivores, as the follow this bigger, bigger, bust pattern.
The new paper is the latest in a now quite impressive series of papers by Carbone and his colleagues building links between body size, metabolism, behaviour and population biology. Here, for example, they describe the shift in prey size described above, and here they relate body size, metabolism, prey density and predator population density.
Eating small stuff is a cheap, low-return strategy, unable to support big carnivores — this limits the maximum size of insectivores. Eating big stuff is high return, but costly, because hunting takes a lot of energy. And it becomes more costly the bigger you get — until at about 1,100 kg, carnivores go out of business.
The largest fossil carnivores are about this size. It also suggests how evolution might paint carnivores into a corner — being big and fierce has obvious advantages, in that you're a top hunter, and you can boss your own species about. But in hard times, you starve. The fossil record seems to show high turnover for fossil carnivores, as the follow this bigger, bigger, bust pattern.
The new paper is the latest in a now quite impressive series of papers by Carbone and his colleagues building links between body size, metabolism, behaviour and population biology. Here, for example, they describe the shift in prey size described above, and here they relate body size, metabolism, prey density and predator population density.
Monday, January 15, 2007
The chances of anything coming from Mars are … 1
In a discovery sure to have major implications, a team of researchers has discovered that the laws of logic and causation are very different on Earth and Mars. The finding suggests that these concepts, often assumed to be universally applicable, may in fact vary from place to place.
"On Earth, we are used to the idea that absence of proof is not proof of absence," explains Mike Trouser, a philosopher at Madeup State University, lead author of the new research. "Similarly, just because a thing might have happened, it doesn't mean that it did happen.
"On Mars, however, we now know that these principles don't apply, and that anything not known to be stonkingly, mind-crushingly impossible must have happened."
As an example, Trouser cites a story in the Guardian on Saturday:
Microbe experiment suggests we could all be Martians
The story refers to a recent paper in Icarus, which found that various microbes and a lichen can survive being sandwiched in rock and then twanked with a steel plate, to recreate the pressures placed on known martian meteorites.
"You might think that this just shows that contemporary microbes can be twanked with a steel plate and come up smiling," says Trouser. "After all, one cannot tell from reading the abstract whether the experiments exposed the microbes to vacuum conditions, extreme temperatures or high doses of radiation." But in fact, the Guardian quotes the paper (although none of the authors, and no independent sources) as saying:
"A strongly confirmed possibility (whatever that is)? Please, you're being too modest," says Trouser.
Initially, Trouser was intrigued why one doesn't see similar results in any other field being reported in this manner. "One doesn't for example, regularly see articles informing us that we don't know for sure that drinking margaritas doesn't make you live longer, or that we can't be sure that cats aren't plotting to overthrow humanity," he points out. "I think the differences in Martian logic now explain this apparent anomaly."
The unique workings of Martian logic don't stop there. At the recent meeting of the American Astronomical Society, it was widely reported that the Viking landers would not have recognized — indeed, would have killed — any life form using hydrogen peroxide as a biological solvent.
The ambiguity of the Viking experiments is nothing new - they have become the grassy knoll of astrobiology. They were designed to look for biological processes — nutrient uptake, gas release — in Martian soil. All gave positive results! Trouble is, so did all nearly all (but not all) the controls. We should probably learn from the Viking experiments to try and design the next life-detectors, rather than endlessly picking over the results.
But, although he believes the existence of H2O2-based life proven, Trouser believes we should also be casting the net wider. "Never mind weird alien biochemistry," he says. "There's plenty of regular life on Mars."
As an example, he cites a 2004 article discussing the general difficulty of recognizing as alive anything that doesn't give you an anal probe and say 'Take me to your leader'. In it, referring to how better we are at spotting microbes now than then, Andrew Steele of the NASA Astrobiology Institute at the Carnegie Institution of Washington says: 'There could have been 10 million bacteria per gram of martian soil, and Viking wouldn't have seen them.'"
"What we now know Steele should have said," says Trouser, "is that there are 10 million bacteria in every gram of Martian soil. For all we know, the Viking mission missed spotting the Flying Spaghetti Monster," he adds. "Hail, then, Martian Flying Spaghetti Monster!"
"On Earth, we are used to the idea that absence of proof is not proof of absence," explains Mike Trouser, a philosopher at Madeup State University, lead author of the new research. "Similarly, just because a thing might have happened, it doesn't mean that it did happen.
"On Mars, however, we now know that these principles don't apply, and that anything not known to be stonkingly, mind-crushingly impossible must have happened."
As an example, Trouser cites a story in the Guardian on Saturday:
Microbe experiment suggests we could all be Martians
Experiments by an international team of researchers back a controversial theory that life flourished on Earth after primitive organisms arrived aboard a meteorite, itself gouged from Mars by a giant impact.
The story refers to a recent paper in Icarus, which found that various microbes and a lichen can survive being sandwiched in rock and then twanked with a steel plate, to recreate the pressures placed on known martian meteorites.
"You might think that this just shows that contemporary microbes can be twanked with a steel plate and come up smiling," says Trouser. "After all, one cannot tell from reading the abstract whether the experiments exposed the microbes to vacuum conditions, extreme temperatures or high doses of radiation." But in fact, the Guardian quotes the paper (although none of the authors, and no independent sources) as saying:
These results strongly confirm the possibility of a 'direct transfer' scenario of 'lithopanspermia' for the route from Mars to Earth, or from any Mars-like planet to other habitable planets in the same stellar system.
"A strongly confirmed possibility (whatever that is)? Please, you're being too modest," says Trouser.
Initially, Trouser was intrigued why one doesn't see similar results in any other field being reported in this manner. "One doesn't for example, regularly see articles informing us that we don't know for sure that drinking margaritas doesn't make you live longer, or that we can't be sure that cats aren't plotting to overthrow humanity," he points out. "I think the differences in Martian logic now explain this apparent anomaly."
The unique workings of Martian logic don't stop there. At the recent meeting of the American Astronomical Society, it was widely reported that the Viking landers would not have recognized — indeed, would have killed — any life form using hydrogen peroxide as a biological solvent.
The ambiguity of the Viking experiments is nothing new - they have become the grassy knoll of astrobiology. They were designed to look for biological processes — nutrient uptake, gas release — in Martian soil. All gave positive results! Trouble is, so did all nearly all (but not all) the controls. We should probably learn from the Viking experiments to try and design the next life-detectors, rather than endlessly picking over the results.
But, although he believes the existence of H2O2-based life proven, Trouser believes we should also be casting the net wider. "Never mind weird alien biochemistry," he says. "There's plenty of regular life on Mars."
As an example, he cites a 2004 article discussing the general difficulty of recognizing as alive anything that doesn't give you an anal probe and say 'Take me to your leader'. In it, referring to how better we are at spotting microbes now than then, Andrew Steele of the NASA Astrobiology Institute at the Carnegie Institution of Washington says: 'There could have been 10 million bacteria per gram of martian soil, and Viking wouldn't have seen them.'"
"What we now know Steele should have said," says Trouser, "is that there are 10 million bacteria in every gram of Martian soil. For all we know, the Viking mission missed spotting the Flying Spaghetti Monster," he adds. "Hail, then, Martian Flying Spaghetti Monster!"
Tuesday, January 09, 2007
Just when you thought...
...Tony Blair had exhausted his capacity to disappoint, along comes this.
Update: I admit to being confused about offsetting. I saw someone compare it to trying to combat sea-level rise by drinking more. But summing up what I've read recently, it seems that it's better not to emit at all (so flying's not ok), but that some projects can help. This piece from the Independent sets out the pros and cons quite nicely. And this from Nature($) goes into a bit more detail. The basic message is energy efficiency and renewable generation, good, trees, bad.
Update: I admit to being confused about offsetting. I saw someone compare it to trying to combat sea-level rise by drinking more. But summing up what I've read recently, it seems that it's better not to emit at all (so flying's not ok), but that some projects can help. This piece from the Independent sets out the pros and cons quite nicely. And this from Nature($) goes into a bit more detail. The basic message is energy efficiency and renewable generation, good, trees, bad.
The owl that gathers manure
Oh dear. Having only recently pronounced the death of animal behaviour, I keep coming across irresistable papers.
“Gather ye cowpats while ye may,” it says in Fungus the Bogeyman. American burrowing owls (Athene cunicularia [isn't that a nice name?]), it turns out, take this advice to heart, collecting manure and scattering it about their burrows.
One hypothesis for this unsavoury behaviour is that the dung disguises the smell of their burrows from predators, but Matthew Smith and Courtney Conway found that manure-strewn burrows were just as likely to suffer predation as clean and tidy ones. Instead, their results suggest, the manure attracts insects and other invertebrates, which the owls eat.
Are there any other animals (besides humans) that lure prey with bait like this? I suspect there are, but none are springing to my mind.
More flimsily, Smith and Conway suggest that the manure also acts as an ‘occupied’ sign, showing other owls that a burrow is taken. What’s wrong with flowers? This is a bird with self-esteem issues. Or maybe it’s some kind of dirty protest. If only we knew what they’re demanding.
“Gather ye cowpats while ye may,” it says in Fungus the Bogeyman. American burrowing owls (Athene cunicularia [isn't that a nice name?]), it turns out, take this advice to heart, collecting manure and scattering it about their burrows.
One hypothesis for this unsavoury behaviour is that the dung disguises the smell of their burrows from predators, but Matthew Smith and Courtney Conway found that manure-strewn burrows were just as likely to suffer predation as clean and tidy ones. Instead, their results suggest, the manure attracts insects and other invertebrates, which the owls eat.
Are there any other animals (besides humans) that lure prey with bait like this? I suspect there are, but none are springing to my mind.
More flimsily, Smith and Conway suggest that the manure also acts as an ‘occupied’ sign, showing other owls that a burrow is taken. What’s wrong with flowers? This is a bird with self-esteem issues. Or maybe it’s some kind of dirty protest. If only we knew what they’re demanding.
Monday, January 08, 2007
Peace breaks out (among ants)
Given that different ant species, and different colonies of the same species, are usually extremely hostile towards one another - fighting, slave making, that sort of thing - this report of a small species living peacefully, and perhaps symbiotically, in the nest of a large one is Quite Interesting. The ants live in hollow tree branches in West Africa; the small one (Pyramica maynei) is also capable of living on its own, but might benefit from the secure environment of the large species' (Platythyrea conradti) nest, possibly in exchange for keeping the place clean.
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