Tag Archives: deer

White-tailed deer in Northwestern Ohio test positive for coronavirus infections

The coronavirus can and did infect white-tailed deer, according to new research. The findings raise some concerns regarding our efforts to contain the virus, as deer could act as a ‘reservoir species’ igniting further outbreaks.

Image credits Robert Woeger.

Researchers at the Ohio State University report that white-tailed deer have tested positive for recent or active coronavirus infections in Northeast Ohio. The results are based on samples taken between January and March of 2021.

While there have been no reported cases of COVID-19 spreading from deer to humans, the authors warn that seeing the virus take hold among deer could pose a threat to public health later down the line. The main concern is that deer could become a reservoir species for the coronavirus, making efforts to control or eradicate the pathogen much more difficult. It also raises the risk of reinfection with the strains currently circulating among deer, or with new strains that mutated through the interaction between the coronavirus and the deer.

Foothold

“Based on evidence from other studies, we knew [deer] were being exposed in the wild and that in the lab we could infect them and the virus could transmit from deer to deer. Here, we’re saying that in the wild, they are infected,” explains Andrew Bowman, the study’s author and professor of veterinary preventive medicine at The Ohio State University.

“And if they can maintain it, we have a new potential source of SARS-CoV-2 coming into humans. That would mean that beyond tracking what’s in people, we’ll need to know what’s in the deer, too.”

The findings are based on nasal swabs taken from 360 wild white-tailed deer across nine different areas in Northeast Ohio. Genetic material indicative of a recent or active coronavirus infection was identified in over 35% (129) of the deer, in samples taken from six locations. Three different strains of the virus were identified in these tests.

The study builds on previous findings of coronavirus infection among white-tailed deer in Iowa, Illinois, Michigan, New York, and Pennsylvania.

The findings lead “toward the idea that we might actually have established a new maintenance host outside humans,” according to Bowman. The virus could mutate in deer, potentially creating an opportunity for new strains to reach humans. It’s also possible that the virus will circulate unmutated among deer while it continues to evolve in humans. If the general population loses immunity to these original strains, the deer could provide an avenue through which they could spill back into our communities.

It’s not yet clear how deer became infected with the coronavirus, nor what (if any) effect this has on their bodies. So far, the team is working on the assumption that the animals contracted the virus by drinking contaminated water, as the coronavirus is known to shed through human stool.

The paper “SARS-CoV-2 infection in free-ranging white-tailed deer” has been published in the journal Nature.

As cities quarantine, animals take to the streets

In Venice, the boats and ferries that used to fill up the canals with hundreds of tourists were now replaced by fishes and even ducks, swimming in clear water. In Japan, hungry deer are taking to the streets; and in Thailand, rival gangs of monkeys are squaring it off in cities.

No, it’s not a Hollywood scenario — nature is starting to reclaim quarantined cities.

Credit Wikipedia Commons

Stay at home. That’s the main message by governments across the world to try to stop the spread of the coronavirus. Many cities, especially in the more affected areas, have been virtually shut off. But, as people withdraw from the outer world, animals are coming in.

All journeys in Venice are now forbidden as part of a set of strict rules of self-confinement, with the only exceptions being walking your dog or buying groceries.

This has led to motorboat taxis, transport and even gondolas emptying the cities’ canals, now taken over by wildlife.

“The water is blue and clear,” hotel manager Gloria Beggiato told The Guardian. “It is calm like a pond, because there are no more waves caused by motorized boats transporting day-tripper tourists. And of course, the giant cruise ships have disappeared.”

Image via Facebook.

Venice isn’t the only city where animals are strolling into town.

In the city of Nara, Japan people reported in their social media seeing hungry deer in the streets and subway stations.

Image credits: okadennis / Twitter.

The deer are reportedly eating potted plants due to a lack of tourists to feed them.

The Nara Park, a popular tourist attraction in Japan, has over 1,000 deer that rarely go outside the 1,240 acres of the park. Until now, that is.

Image credits: okadennis / Twitter.

Visitors to the park usually buy rice crackers to feed the deer. Now, with no tourists, the deer began wandering into the city searching for food. Doing so can be risky for them, experts warned, as they can be hit by cars or eat plastic bags, or even get lost.

Credits: Wikipedia Commons

Meanwhile, in Thailand, two gangs of monkeys are reportedly fighting for supremacy in the city’s mostly-empty plaza. In a video that went viral, the monkey groups started a 10minute fight against each other, leaving the few bystanders shocked.

Here too, the cause might be a shortage of food brought in by declining tourist numbers.

The animals live in the Phra Prang Sam Yot monkey temple but they are dealing with a scarcity of food due to the lack of tourists in the area. That has led them to go into the city and try to get some food.

“The fall in tourist numbers because of Covid-19 may have indeed brought about a shortage of food supply for them,” Asmita Sengupta, an ecologist, told The New York Times. “Feeding the monkeys can have detrimental effects. Once they get used to being fed by humans, they become habituated to humans.”

The effect that the lack of tourists to feed the animals will have on the animals remains to be seen. But experts believe that most of them will likely be fine.

“Most animals living in urban environments already have flexible diets, so chances are good that a lot of these animals are going to be OK,” Christopher Schell, an urban ecologist at the University of Washington, told the NYT.

EDIT: There are multiple stories floating around social media about dolphins in Venice and elephants in tea fields. These are not true and are misleading.

‘Lost’ deer species rediscovered after 30 years

Camera-trap photo of silver-backed chevrotain (Tragulus versicolor).
Image credits: SIE/GWC/Leibniz-IZW/NCNP / Andrew Tilker

The Vietnam mouse-deer (which also goes by the name of silver-backed chevrotain, or more technically, Tragulus versicolor) was first described in 1910, based on specimens near the city of Nha Trang, Vietnam. This bordering area between Vietnam and Laos hosts one of the richest biodiversities in the world. However, as of 1990, it was believed that the mouse-deer was no longer a part of that biodiversity.

High levels of hunting (particularly with snares) and habitat loss led the numbers of these deer to decline, with no official sightings being reported throughout the 1990s. Researchers feared that the species had gone extinct, which seemed to be more and more likely as years passed on.

But An Nguyen from the Leibniz Institute for Zoo and Wildlife Research wasn’t so sure. Along with Andrew Tilker and other colleagues, Nguyen set up a plan to find out whether the chevrotain is still around or it actually went extinct. They spoke to locals around the Greater Annamites Ecoregion of Vietnam and Laos who claimed to have seen the species. Their stories seemed consistent, but there was a problem: the silver-backed chevrotain looks a lot like other mouse-deer which inhabited the area.

So the research team set up 30 motion-activated cameras in the Nha Trang area to see whether they could find evidence of this critter.

“We had no idea what to expect, so I was surprised and overjoyed when we checked the camera traps and saw photographs of a chevrotain with silver flanks. For so long this species has seemingly only existed as part of our imagination.”

After six months of camera observations, the researchers confirmed over 200 detections (although it’s not clear how many individuals were observed). The locals were right in their claims that the species never went extinct, leaving researchers overjoyed.

” In an age of mass extinctions, confirming the survival of lost species provides rare second chances for biodiversity conservation,” researchers write. “The silver-backed chevrotain Tragulus versicolor, a diminutive species of ungulate known only from Vietnam, has been lost to science for almost three decades. Here, we provide evidence that the silver-backed chevrotain still exists and the first photographs of the species in the wild, and urge immediate conservation actions to ensure its survival.”

While it’s always exciting to rediscover a species once thought to be lost, the fate of the silver-backed chevrotain is not yet certain. At best, the species still hosts a small but healthy population. At worst, only a few individuals survive in the area, and the species is still on the brink of extinction.

Researchers have developed a mitigation plan dealing with the two main threats to the species: habitat alteration and poaching. Poaching is probably the more pressing issue of the to, so reducing snares is the first and very critical step in ensuring that we don’t lose the species again.

The study has been published in Nature.

Fishermen find 10,000-year-old skull and antlers belonging to extinct giant elk

Deep down, every fisherman hopes today will be the day they will find the big one — but not too many fishermen imagine finding Holocene remains.

The antlers and skull belong to the largest deer species that ever lived. Image credits: Ardboe Gallery.

It was a day much like any other for Raymond McElroy and Charlie Coyle. They went out fishing for pollan (a whitefish) in Lough Neagh, a freshwater lake in Northern Ireland. When they cast their net, they knew they had found something big; they just didn’t know how big — and how old.

“It came up in the net on the side of the boat. I thought it was a bit of black oak to begin with,” McElroy told Belfast Live. “I was shocked to begin with when I got it over the side and saw the skull and antlers. It’s pretty good.”

The skull and antlers belong to a species that used to roam the lakeshore tens of thousands of years ago until it went extinct some ten millennia ago. The skull that the two fishermen found may have been one of the very last that roamed the area.

The intact skull and antlers measured almost 2 meters across (6 feet), and belonged to the Great Elk, Megaloceros giganteus), sometimes referred to as Irish Elk.

[panel style=”panel-default” title=”The Irish Elk — the great misnomer” footer=””]It’s funny that the species would be called the Irish Elk, for it is neither exclusively Irish nor an elk. It is, however, the largest known deer species to ever walk the face of the Earth, standing up to up to seven feet at the shoulder (2.1 meters), with antlers spanning up to 12 feet (3.65 meters).

It’s not exactly clear what led to the extinction of this magnificent beast, but it likely has a lot to do with the changing conditions of the Holocene.

Unable to adapt to the changing environmental conditions of the last glaciation or the marked transition that occurred after the final retreat of the ice sheet, the largest deer that ever lived became extinct. It was a study including this species that first started to convince skeptic naturalists that the total extinction of a species was possible.

[/panel]

Raymond McElroy with his lucky catch Image credits: Ardboe Gallery.

Dr. Mike Simms at the Ulster Museum, who took custody of the finding, commented for Belfast Live:

“It’s the first really good one I have seen in 20 years. They’ve been extinct since 10,500 to 11,000 years ago in Ireland. They hung on Siberia until about 6,500 years ago.”

“They came in (to Ireland) when the weather was great on the grass plains, but then the trees started to grow — giants antlers aren’t great in the forest.”

Find a mate or stay safe? A tricky decision for male deer

Some male elk (a North American species of deer) shed their antlers earlier in the year, which favors them to get better mating partners. However, this also leaves them defenseless for a while — and wolves have picked up on this, targetting them specifically.

A male elk’s antlers are a good indication of strength and fertility, traits which are valued by potential mates.

The main purpose of antlers is sexual selection: males use antlers to compete with each other, and females also prefer males with big antlers, as they indicate strength and fertility. Like other deer, elk shed their antlers over a two-three month period, right after the mating season has ended. This allows them to grow new antlers by the next mating season.

But antlers also serve a secondary purpose — they help defend against predators like wolves, a new study suggests.

[panel style=”panel-default” title=”ElkS” footer=””]Also called wapiti, elks (Cervus canadensis) are some of the largest deer species in the world.

They’re native to the forest edge habitats of North America and eastern Asia, but they have also adapted well to the countries in which they have been introduced, including Argentina and New Zealand.

Some cultures cherish them as a spiritual force, yet they are often hunted as game. In Asia, some of their body parts are used in traditional medicine.[/panel]

Wolves, intelligent creatures that they are, picked up on this fact. In a new study published in Nature, University of Montana researchers report that wolves target elk who have shed their antlers, even if they are fitter and apparently more difficult to hunt.

“We show, however, that male elk that cast their antlers early are preferentially hunted and killed by wolves, despite early casters being in better nutritional condition than antlered individuals,” researchers write. “Our results run counter to classic expectations of coursing predators preferring poorer-conditioned individuals, and in so doing, reveal an important secondary function for an exaggerated sexually selected weapon—predatory deterrence.”

So the elk are faced with an interesting trade-off: do they shed their antlers early, and face an increased wolf risk but raise their chances of finding a mate, or do they maintain them more — which keeps them safer, but makes them less attractive?

In this case, safety won, researchers say: uniquely among North American deer, elk retain their antlers long after they fulfill their primary role in reproduction. In other words, as exciting as mating is, not being eaten by wolves takes priority. However, researchers say, the need to regrow antlers results in a trade-off between these two functions — and this trade-off likely influenced the species’ evolution over time.

The study “Predation shapes the evolutionary traits of cervid weapons” has been published in Nature Ecology & Evolution

Deer CWD.

The first case of chronic wasting disease suspected in Jackson County

A doe carcass may be evidence of Jackson County’s first case of chronic wasting disease.

Doe.

A healthy doe.
Image via Maxpixel.

State officials report that a 3-year-old doe in Jackson Country is suspected to have died from chronic wasting disease, a condition that creates the so-called “zombie deer”. If confirmed, this would be the first recorded case of the disease in the county.

Deerly departed

A press release from the Michigan Department of Natural Resources (DNR) reports that landowners in Spring Arbor Township contacted the agency earlier this month about a deer that died on their property. The deer looked ill, they said. DNR staff arrived at the location and examined the deer to determine the cause of its death. As part of the procedure, they sent three tissue samples to the Michigan State University Veterinary Diagnostic Laboratory.

Initial tests came out positive for the disease. The samples have since been forwarded to the U.S. Department of Agriculture’s National Veterinary Services Laboratory (NVSL) for confirmation. The DNR is currently waiting for the results. If confirmed, this will be the first recorded case of chronic waste disease in Jackson County.

“We are committed to maintaining healthy Michigan wildlife for current and future generations,” said DNR Director Keith Creagh. “One of our chief goals is to slow the spread of chronic wasting disease to other areas of the state.”

“That’s why we’ve taken strategic action, in partnership with local communities, hunters and others, to best address CWD in Michigan’s deer population.”

Chronic waste disease is very similar to the mad cow disease. It’s an incurable, fatal neurological condition that afflicts white-tailed deer (Odocoileus virginianus), mule deer (O. hemionus), elk (Cervus canadensis) and moose (Alces alces). During its early stages, the disease isn’t even outwardly evident — infected deer look just as perky as their healthy counterparts. Its later stages, however, are quite horrific; animals in these stages have been described as ‘zombies’, being sickishly thin, unalert, and unafraid of humans.

Deer CWD.

Deer showing obvious signs of chronic wasting disease.
Image credits Terry Kreeger / Wyoming Game and Fish and Chronic Wasting Disease Alliance.

Over 31,000 deer have been tested for the disease since May of 2015. Chronic wasting disease already has been confirmed in Clinton, Ingham, Ionia, Kent and Montcalm counties. If the NVSL confirms that we are looking at a case of chronic waste disease, this would mark the 58th recorded case in Michigan.

Although the case is not yet confirmed, deer farms in the area have already been notified to take extra precautions.

Alarmed by this possible spread of the disease, the DNR is asking for help from hunters and the wider public. If you see any deer that’s unusually thin and lethargic, with drooping ears and head, report the sighting to your local wildlife office or via this online form. Animals that are exhibiting unusual behavior — most notably those that act tame around people and let humans approach them — should also be reported.

Golden Pheasant.

Reforestation efforts bring back hundreds of species to China

China’s reforesting, and their efforts are bringing back species that had previously disappeared from the country’s lands.

Golden Pheasant.

The golden pheasant (Chrysolophus pictus). Image credits Petr Kratochvil.

For the past few decades, China has been pursuing an ambitious project — to increase the amount of land covered by forests to 23% of the country’s total land area by 2020.

Not only is this good news for Chinese nationals, who have been struggling with the country’s notoriously high levels of pollution, but also its wildlife. The resurgent forests are bringing back species to Chinese habitats from which they were previously considered extinct, report researchers from the Beijing Normal University (yes, that really is their name).

Hot new real estate

Using infrared cameras hidden in the Ziwuling Forest Area in Yan’an, Shannxi province, northwestern China, the team documented the presence of several rare species previously thought extinct in the area. The observations are quite encouraging, spotting the largest population of North-Chinese leopards (Panthera pardus orientalis) ever recorded in the region.

Other notable appearances include the golden pheasant (Chrysolophus pictus) — a species that has established populations around the world — foxes, and roe deer (Capreolus capreolus). Reforestation projects have been underway around Yan’an since 1998.

“The nature reserve has a large population of wild boars and roe deer, as well as small and medium-sized carnivorous animals such as ocelots and red foxes,” Feng Limin Feng, associate professor from Beijing Normal University, told China Plus.

Overall, the team has documented 263 different species in the area. Eight of these are listed as critically endangered on the IUCN’s Red List, and 29 others are listed as threatened. Such a diverse ecosystem is a major leap forward for the area, traditionally devastated by logging and deforestation.

“If it was not for environmental protection we’ve undertaken, it’s likely none of these animals would have survived,” Feng adds.

The reforestation efforts are part of China’s larger drive to improve environmental protection and combat climate change.

As we’ve written earlier today, climate change and habitat erosion together pose a massive threat to the viability of Earth’s ecosystems. I’m glad to see China tackling the issue from the roots up.

Japanese monkeys are apparently having sexual intercourse with deer

Nature is really messed up sometimes.

Adolescent female Japanese macaque on the back of a male sika deer. Courtesy of Noëlle Gunst

Researchers from the University of Lethbridge in Canada first spotted the behavior earlier this year, but it was a single anecdotal episode. It wasn’t clear why or even exactly what was happening.

“Even the sexual nature of this interaction was not clearly demonstrated,” said Noëlle Gunst.

So she and her colleagues did what you’d expect from scientists: they went back to look for more evidence. They looked at different types of sexual relationships, particularly between adolescent female monkeys and male deer.

“We observed multiple occurrences of free-ranging adolescent female Japanese macaques (Macaca fuscata) performing mounts and sexual solicitations toward sika deer (Cervus nippon) at Minoo, central Japan,” researchers write in the study.

Japanese macaques and sika deer have complex relationships. The macaques sometimes ride deer just like humans ride horses. The deer seem to tolerate it in exchange for grooming and leftover food. But this particular relationship is quite different.

Researchers liken it to homosexual monkey-monkey interactions, where female macaques mount each other. The females also mount the deer, using the same type of movement and the same vocalizations — so the deed appears sexual, at least for the monkeys. The deer, on the other hand, don’t seem as involved.

Some deer shook the macaques off. But others, especially adult male deer, let them do their thing. Some don’t even stop eating while the monkeys are humping them. Still, the acts were persistent and went way beyond mere thrusting or humping. The “monkey-to-deer solicitations … were persistent and conspicuous,” the researchers write. All in all, researchers documented 13 successful pairings and 258 separate mounts. So… what does it all mean?

Interspecies sexual relationships are not unheard of in the animal world, though generally, they’re between closely related species — nothing like this. The purpose of the act can’t possibly be reproductive, so the macaques are doing it for a different reason. Researchers have a few ideas.

The first is that this is a way for adolescent monkeys to start “learning sex” and/or explore their own sexuality. It could also just be a way for them to obtain sexual stimulation with no strings attached — something I’m sure many of us can empathize with. Younger female macaques have also been reported to have intercourse with each other, presumably for the same reasons. Another possibility is that they just don’t have any sexual partners available. Adolescent females are routinely rejected and are not considered desirable among the population.

Lastly, it could also be a non-sexual display. It might be a cultural phenomenon, a social fad. Time will tell, researchers say. They plan on carrying out more observations to detail the nature and purpose of this unusual behavior.

Journal Reference: Noëlle Gunst, Paul L. Vasey, Jean-Baptiste Leca. Deer Mates: A Quantitative Study of Heterospecific Sexual Behaviors Performed by Japanese Macaques Toward Sika Deer.

How bringing cougars to cities could actually save lives

Allowing cougars to re-populate back to their historic range could save hundreds of human lives and prevent tens of thousand of injuries, a new study reports. Counter-intuitive as this may seem, the numbers actually add up — while we may expect some property damage from the predators, they’d actually help us out in the end by keeping the US’s deer population in check.

Deer are most active between 6 and 9 p.m. and generally travel in herds – if you see one, there is a strong possibility others are nearby.
Image credits State Farm/Flickr

If I asked you to pick the animals with the highest human death toll between deers and cougars, which would you pick? The cougars, undoubtedly. And you’d be wrong. Sure, a cougar is fiercer than a deer, it has both teeth and claws and isn’t shy about using them while a deer is uh…a nuisance? But by sheer weight of numbers (and an inability to act when confronted with headlights) white-tailed deer in the US cause more than a million car collisions, resulting in more than 200 deaths, every year.

By the early 1900s, we pushed cougars away from our cities because they were dangerous, but a new study suggests this exact trait is why we should bring them back. Laura R. Prugh, a wildlife scientist at the University of Washington, Sophie L. Gilbert, a wildlife ecologist at the University of Idaho and several colleagues argue that allowing eastern cougars to return to their historic range could prevent 155 human deaths, 21,400 human injuries, and save $2.3 billion over the course of 30 years.

The team bases their estimations on studies they performed in 19 states including South Carolina, Maine, Wisconsin, Ohio, and Missouri. Delaware, Rhode Island, Maryland and Illinois were historically part of the eastern cougar’s territory, however, they lack the required open forestland to support a viable cougar population today, the team reported. They also said that if left to their own devices, it’s entirely possible that the cougars will re-populate these areas on their own: over the past few decades, they’re been sighted in parts of the Midwest and more recently in the East. Dr. Prugh advocates for this kind of natural repopulation, which would face less resistance than a human-engineered one, she believes.

Pictured: statistically less dangerous to you than a deer.
Image credits Wikimedia user Dcoetzee

They looked at the number of individuals to see how deer populations grow in each area, how many car crashes involve deer and how they increase as the deer population grows. They looked at cougars’ hunting behavior, and settled for an average of 259 deer kills per individual per average lifespan of 6 years, and an 850 square miles area of forested land needed to sustain a wild population of the felines.

They then tested several mathematical models to calculate the cougars’ effect on the deer population. The first question they needed to consider was if cougars would prey on the deer that are too starved, old, or sick to survive and don’t actually cause accidents. Dr. Prugh calculated for a “conservative” 75% of deer kills as animals that would’ve died anyway.  They also considered that as adult deer decrease in number, more fawns survive — so killing deer doesn’t immediately shrink the population.

But it’s not all roses. The catch is that we’re dealing with dangerous, deadly predators here, which are perfectly capable of killing humans. Their population would stabilize at considerable numbers in some states — about 1000 in New York and Wisconsin each, around 350 in Missouri and between 8-15 in New Jersey, the team estimates. They also expect to see livestock loss of around US$2.35 million per year in the areas, and some pet loss, though the team wasn’t able to estimate this — since there is little data on what happens to pets after they are lost.

The scientists also estimated that we could expect less than one victim per year, for a total of under 30 lives lost, far less than the number of lives saved. But they admit that the emotional response to predators is one element they can’t factor in — no matter how many people are saved in the end, death by deer is very different to death by cougar.

“The idea of being killed in a car crash with a deer just doesn’t scare people the way the idea of a cougar leaping on your back in the woods does,” Dr. Prugh said.

But she hopes that if cougars do return to the Eastern states, an understanding that they could bring tangible benefits will make people “a little more accepting, even if they are still scared.”

The full paper titled ” Socioeconomic benefits of large carnivore recolonization through reduced wildlife-vehicle collisions” has been published online in the journal Conservation Letters.

New reserach suggests mammals are tunned to the crying calls of infants, even when these don't come from members of their species. Photo: Flickr Commons

The primal call: mammals may respond to baby cries even when they’re from another species

New reserach suggests mammals are tunned to the crying calls of infants, even when these don't come from members of their species. Photo: Flickr Commons

New reserach suggests mammals are tuned to the crying calls of infants, even when these don’t come from members of their species. Photo: Flickr Commons

Crying is a baby’s principal means of communicating its negative emotions, yet no matter how annoying and painful it may be to hear those high pitched screams, humans are naturally drawn to this call. Well, it seems our brains are hard-wired to respond strongly to the sound, making us more attentive and priming our bodies to help whenever we hear it. A new study by biologists at the University of Winnipeg, Canada suggests that this isn’t a solely human trait. Their findings suggest there’s a common element among the cries of most, if not all mammalian species that draws adults to investigate as a primal instinct, ignoring any risks in between.

The call

Susan Lingle, a biologist at the University of Winnipeg, and colleagues recorded the calls made by infants from a variety of mammal species when separated from their mother or otherwise threatened. These were then played our in the Canadian prairies from hidden speakers to wild mule deer (Odocoileus hemionus). The researchers noticed that mother deer quickly moved towards the source of the sound when the cry of an infant deer was played, but same held true whether the cries came from infant fur seals, dogs, cats or humans. All these species call at roughly the same high pitch. Even the ultrasonic calls of infant bats attracted the mother deer, of course after being tuned to a lower frequency using software.

The findings suggest there’s a common acoustic element that some mammals are hard-wired to respond to and investigate, at the cost of taking risks. It may be that this common element was kept across species, even in those whose lineages separated more than 90 million years ago.

“These are calls that are generally made in a life-or-death situation,” Lingle says. “I think the advantage of securing survival for your offspring outweighs the potential for error.”

Findings appeared in the journal American Naturalist.