No legal limit for bats?

  • A bat in the hand

    Timeline, 2010: People with a blood alcohol level of 0.3 percent are undeniably kneewalking, dangerously drunk. In fact, in all 50 states in the US, the cutoff for official intoxication while driving is 0.08, almost a quarter of that amount. But what has people staggering and driving deadly appears to have no effect whatsoever on some bat species.

Why, you may be wondering, would anyone ask this question about bats in the first place? Bats are not notorious alcoholics. But the bat species that dine on fruit or nectar frequently encounter food of the fermented sort, meaning that with every meal, they may also imbibe a martini or two worth of ethanol.

Batty sobriety testing

Recognizing this exposure, researchers hypothesized that the bats would suffer impairments similar to those that humans experience when they overindulge. To test this, they selected 106 bats representing six bat species in northern Belize. Some of the bats got a simple sugar-water treat, but the other bats drank up enough ethanol to produce a blood alcohol level of more than 0.3 percent. Then, the bats got the batty version of a field sobriety test.

Bats navigate by echolocation, bouncing sound waves off of nearby objects to identify their location. To determine if the alcohol affected the bats’ navigation skills and jammed the sonar, the researchers festooned a ceiling with dangling plastic chains. The test was to see if the animals could maneuver around the chains while under the influence of a great deal of alcohol. To their surprise, the scientists found that the drunk bats did just as well as the sober ones.

Some bats hold their drink better than others

Interestingly, the bats did show a human-like variation in their alcohol tolerance, with some bats showing higher levels of intoxication than others. But one question that arises from these results is, Why would bats have such an enormous alcohol tolerance?

As it turns out, not all of them do. These New World bats could, it seems, drink their Old World cousins under the table. Previous research with Old World bats from Egypt found that those animals weren’t so great at holding their drink. Thus, it seems that different bat species have different capacities for handling—and functioning under the influence of—alcohol.

One potential explanation the investigators offer for this difference is the availability of the food itself. In some areas, fruit is widely available at all times, meaning that the bats that live there are continually exposed to ethanol in their diet. Since they can’t exactly stop eating, there may have been some selection for those bats who could get drunk but still manage to fly their way home or to more food. In other bat-inhabited areas, however, the food sources vary, and these animals may not experience a daily exposure to intoxication-inducing foods.

Alcohol driving speciation?

This study may be one of the first to identify a potential role for alcohol in the speciation of a taxon. Bats as a group underwent a broad adaptive radiation, meaning that there was a burst of speciation as different bat species evolved in different niches. Factors driving this burst are thought to have included different types of fruit; for example, tough fruits require different bat dentition features compared to soft fruits. Now, it seems that alcohol availability may also have played a role in geographical variation of alcohol tolerance in bats. Bats with greater tolerance would have been able to exploit a readily available supply of alcohol-laden foods.

What’s next in drunk-animal research? The investigators who made this unexpected bat discovery have a new animal target—flying foxes, which aren’t really foxes at all but yet another species of bat that lives in West Africa. We’ll have to wait and see how these Old World bats compare to the New World varieties when it comes to holding their liquor.

Advertisements

Fish can count, too

One, two, three...

Timeline, 2008: We tend to think of a few things we do as being uniquely human. And then we keep finding other organisms that can do them, too. Walking on two legs? Meet the orangutan, walking upright in the trees. Tool use? Crows can make a hook to fish meat out of a tube. The ability to talk? Seems that Neanderthals might have had that, also. OK, well what about counting, having number sense? Baby chickens share this trait with us. To the growing list of other animals that do as well—which includes dolphins, rats, and some monkeys—you can now add the mosquitofish.

Mosquitofish vs Munduruku

Yes, apparently fish can also count, in some cases as well as infants ages 6 to 12 months. In fact, when compared to some natives of the Amazon, the Munduruku, which have limited number language, the fish may even be comparable. The Munduruku people see no value in having a construct for counting beyond five. The mosquitofish, on the other hand, can count about that high and estimate with even higher numbers.

Number sense: It’s not just for people any more

Number sense can be broken down into three paths of perception. We can visually estimate what we see, as people do when they report crowd counts for huge parades or demonstrations. We can also visually count individual units, as we might do just looking at the fingers on one hand. And humans also have the ability to verbally count, theoretically to infinity given sufficient time. While mosquitofish obviously do not count out loud, they do appear to have visual estimation and counting abilities.

Neither is sexual harassment

Their estimation abilities first emerged as a result of sexual harassment. Researchers studying the guppy-like fish noticed that when a male harassed a female, the female fish would take refuge with a group of fish nearby. If there was a choice of groups, or shoals, of different sizes, she would choose the larger of the two. Of course, her ability to tell “larger” might have had nothing to do with actual numbers but instead with the area that the fish occupied. To assess this possibility, researchers performed a number of complex experiments. Their results showed that the females were not relying in occupied area to figure out which group had more fish. They really were using visual number estimation to decide.

In fact, they seem to use ratios in their determinations, but the ratios need to meet a threshold of difference for the estimations to work. For example, a mosquitofish seems able to distinguish a group of 16 fish as being larger than a group of 8 fish, a ratio of 2:1. But the fish cannot tell a group of 12 from a group of 8, proving unable to distinguish a 3:2 ratio.

Estimating, counting: These fish are brilliant

With lesser numbers, up to about four, however, the fish discard visual estimation and rely instead on actual visual counting. In what really was a clever set of experiments, the research team let an individual female fish spend an hour exploring two areas of an aquarium. In one area, she could see a group of four fish but could only see each fish one at a time. In the other area was a group of three fish, again only visible to the female one at a time. After letting her explore, the researchers then determined where the female spent more time. The fish spent about twice as long swimming close to the larger group. In other words, the fish seems to have counted the number of individuals in each group and based on their counting, figured out which area of the aquarium had the larger group.

Pretend you’re a fish

To get in tune with how meaningful this ability is, visualize the experiment yourself as a human (you’re human, right?). Stand in front of two open doorways. In one doorway, four people appear, one at a time. In the other doorway, three people appear, one at a time. You can count them, distinguishing each different individual, and can tell which doorway leads to the larger group of people. That’s how smart the mosquitofish is.

Has the ivory-billed woodpecker left the building?

Watercolor painting of ivory-billed woodpeckers from Audubon's Birds of America, 1826.

Imagine waking up one morning to real film footage of a duckbill dinosaur wandering around the Great Plains. Your reaction might be similar to that of birders around the world when Science magazine reported in 2005 that the ivory-billed woodpecker, thought for 60 years to have been extinct in the United States, still existed.

A forest bird of legend

The woodpecker entered birder and ecologist lore when its numbers declined in the early part of the 20th century. Its habitat was bottomland forest in the southeastern United States and Cuba, and its niche included drilling into mature trees. When people came along, logging away the woodpeckers’ homes, the bird appeared to vanish. By the 1920s, we thought it had disappeared forever, although in 1943, there was a single confirmed sighting of a lone female, flying over the stumps of an old-growth forest. She became a central figure in a PhD thesis in 1944. Then for 60 years, silence.

False calls

Well, not complete silence. There were many reports of sightings, but most were traced to another woodpecker species, the pileated woodpecker. The ivory-billed woodpecker differs distinctly from its pileated cousin in beak color, in having white patches on its back when perched, and in its size and the solid-black crest of the female. It has a three-foot wing span, which is huge for a woodpecker, and can grow as large as 20 inches long. It is a big, beautiful, and surprising bird, with a bright red crest on the males that must be startling to see among the cypress of a bottomland forest.

A mesmerizing obsession

Birders, possibly the most obsessive of any taxon fan club, had long wandered into the swampy bottomlands of Arkansas and Louisiana, trying to find ivory-billed woodpeckers. There was a confirmed sighting in Cuba in the ‘80s, and over the decades, people have claimed sightings or reported having heard the ivory-billed’s call. Professionals and amateurs alike have waded among snakes and fought off bugs, playing tapes of the call and listening for a response. At one point, searchers found a nest that had an ivory-billed look to it and trained a remote-sensing camera on it, but saw nothing.

And then in 1999, a kayaker thought that he had seen a pair of the birds. His report received serious attention from the government, local papers, and academic groups interested in the woodpecker both for its inherent beauty and for its status as a symbol of the price of our destructive tendencies. Soon, the old forests of the southeast were crawling with ornithologists, all hoping to catch a glimpse, take a picture, and emerge with definitive proof that a bird long thought to be extinct had survived.

The beat of the forest, revived?

Some people heard the drumming sounds the woodpecker is known to make. A handful of people who really knew their woodpeckers reported sightings. But it was a four-second video of the shy, reclusive bird that clinched it. The video is short and blurry, taken from a kayak in late April of 2004 on a camcorder. But even its poor quality couldn’t hide the distinctive markings and features of the ivory-billed woodpecker.

The confirmation set the world of ornithology astir, but it also reverberates among ecologists and environmentalists. The fact that at least one male ivory-billed woodpecker exists indicates that at least one breeding pair must have survived into the 1990s because the birds live 15 to 20 years at most. And it also might have meant a second chance for us and the woodpecker. Unfortunately, according to a recent report from Cornell researchers who have spent five years looking for more signs of the bird, “it’s unlikely that there are recoverable populations” of the bird where they’ve been searching.

Sad update: Baby red panda has died

This update on the baby red panda from a news release via the National Zoo:

An animal keeper at the Smithsonian’s National Zoo discovered a recently born red panda cub lifeless yesterday during evening animal rounds. The 21-day-old cub was immediately transported to the veterinary hospital where a veterinary team confirmed his death. Born June 16, this male was the first cub for parents Shama and Tate and the first cub born at the Zoo in 15 years.

Zoo keepers had closely observed the cub since his birth. First-time mother Shama had moved the cub around the outdoor exhibit instead of keeping the cub in a nest box, as would be expected. As a result of Shama’s behavior, the exhibit was roped off to the public in order to provide her with peace and quiet. Animal care staff weighed the cub regularly, observed and reviewed the behavior of the cub and parents at least twice daily and volunteers monitored the behavior in-person and via camera several hours each day.

Due to the recent extreme heat, keepers were extra vigilant maintaining the animals’ cooling centers (chilled spaces within the exhibit). Nonetheless, there is a 50 percent mortality rate for red panda cubs born in captivity. Pathologists performed the necropsy last evening but the definite cause of death was not evident. Additional testing, including histopathology, is underway and should provide additional information.

The National Zoo has been breeding red pandas successfully for 48 years. Since 1962, 184 cubs have been born at both the Zoo and the Smithsonian Conservation Biology Institute in Front Royal, Va., with a mortality rate of about 40 percent, below the national average. Currently there is one cub at the Front Royal facility.

“This is an enigmatic and important species,” said Dennis Kelly, director of the National Zoological Park. “We’re deeply disappointed to lose this cub but there are inherent risks in the conservation of rare species. Our cumulative breeding and research success has positioned the Smithsonian’s National Zoo as one of the leaders in the field of red panda conservation. We’ll stay the course until this animal is no longer listed as vulnerable.”

Red pandas breed once a year and animal care staff anticipate that they will breed again next year.

Awww. Baby red panda

It was love at first sight for Shama and Tate, the red pandas at the Smithsonian’s National Zoo, and now, nearly 1½ years after they were introduced, the pair has a cub as evidence of their strong bond. On Wednesday, June 16, Shama gave birth to a single cub—the first for both of the Zoo’s red pandas (Ailurus fulgens) and the first red panda cub born at the National Zoo in Washington, D.C., in 15 years.

Red pandas have a baby. It’s very cute.

The National Zoo is celebrating its first birth of a red panda in 15 years. The history of the red panda–at least, of its classification–is complicated. More on that in a mo. What’s significant here is its current situation. Thanks to habitat loss, the species has declined in the wild to fewer than 2500 individuals, and it is endangered. So a birth–especially between an apparently happy couple with a strong mutual attraction–is a success for the zoo and for red panda conservation, too.

The proud mother was born at the Smithsonian Conservation Biology Institute in Front Royal, Va., and more than 100 surviving cubs have been born at both this research facility and the Washington, D.C., campuses since 1962.

Panda or raccoon?

Taxonomists–the folks who classify organisms by relatedness–have had a conundrum on their hands with the red panda. You’d think that the name says it all: it’s a panda, right?

Well, no. Nothing’s ever that easy in taxonomy. For some time, arguments that it was a relative of the raccoon held weight. But the animal has some strong panda-like traits, including an affinity for bamboo and similar habitats to the giant panda. But they differ in their far more diverse diet and greater habitat distribution.

The panda’s thumb

The giant panda has a faux thumb that’s really just a bone extension of the wrist bones. It’s not an opposable thumb like the one primates have, but the giant panda uses it in a thumb-like way. The red panda happens to share this odd trait. They also share many similarities in their DNA, which ended in the red panda briefly joining the bear family.

So, is it a panda or a raccoon?

The species also has some commonalities with the raccoon, including the ringed tail and more diverse diet compared to the giant panda, one that includes a taste for bird eggs. For these reasons, it also has been classified into the raccoon family. So, which family is it?

It’s neither. While the red panda has now been classified as a distant relative of the giant panda–the bamboo! the “thumb”!–it falls into its very own family, the Ailuridae, of which the red panda, or Ailurus fulgens, is the sole member. Unlike bears, this species arose in Asia and never made the trek to the “new world.”

Interesting note, the snow leopard–another severely endangered species–is their sole wild predator.

Wordless Wednesday: Dolphin diplomacy

(almost wordless…)

Move over, cockroaches. Dolphins have the communication game down to diplomacy:

(Credit: iStockphoto/Stephan Zabel)

Recorded "bee alarm" calls send pachyderms packing

Elephants are terrified of bees

Forget about the mouse freaking out the elephant. What these land behemoths fear most may be bees. Researchers report in PLoS ONE that African elephants live in such terror of African bees that the pachyderms have a specific alarm call that means “Bees!” Recordings of the call could send herds stampeding, even with no bees in sight or earshot.

Birds do it, prairie dogs do it, and so do elephants

Vulnerable vertebrates living in social groups often have calls specific to danger. Prairie dogs throw up little arms and let out a whoop that means “Hawk!” or “Snake!”. Some primates and birds also have vocalizations specific to certain threats. But why do elephants, with lions as their only non-human predator, fear bees so much? A swarm of angry African bees can sting their soft parts around the eyes and mouth, and the hide of young elephants isn’t tough enough yet to withstand the stingers.

Rumble in the jungle, er, savannah

When a bee threat is detected, the elephants emit a particular rumble (listen here), just one of the many vocalizations these social animals use to communicate with each other. Subtle variations in this rumble, which elephants may produce by small adjustments in lip and tongue, can send a pachyderm pack running as though a hive of angry bees were on their trail. But another small adjustment can leave most of them standing there, staring. These subtle changes may even cue the herd to the nature of a specific danger, as is the case with other vertebrate groups that sound alarm calls.

Other differences may not be so subtle. While bees get a rumble from the elephants, lions get an unmistakable elephantine reception that includes threatening roaring and trumpeting.

%d bloggers like this: