Monday, December 30, 2013
The federal government's proposal to discontinue protection for the gray wolf across the United States could have the unintended consequence of endangering other species, researchers say.
As written, scientists assert, the proposed rule would set a precedent allowing the U.S. Fish and Wildlife Service (FWS) to declare habitat unsuitable for an endangered animal because a threat exists on the land – the exact opposite of the service's mandate to impose regulations that reduce threats against imperiled species.
The FWS has "conflated threats with habitat suitability" by stating that U.S. land currently unoccupied by wolves – most of the country that historically served as wolf habitat – is now unsuitable because humans living in those regions won't tolerate the animals, the lead scientist said. This claim runs counter to existing research, which the service did not cite in its explanation of the rule.
"The Fish and Wildlife Service is supposed to detail what the threats are and if they're substantial enough, they're supposed to list a species and put in place policies to mitigate the threats," said Jeremy Bruskotter, associate professor in The Ohio State University's School of Environment and Natural Resources and lead author of the paper.
"Here, they're saying that they recognize the threat of human intolerance and instead of mitigating the threat, they're just going to say the land is unsuitable."
Were this rule to stand, he said, "Anytime the U.S. Fish and Wildlife Service finds that something is in the way of a species' recovery, they can just say the habitat is unsuitable for the species and disregard the threat altogether."
FWS proposed removing the gray wolf (Canis lupus) from the list of threatened and endangered species in June. The rule covers most of the continental United States where wolves historically existed, before being exterminated by people in the late 19th and early 20th centuries. Public comments closed Dec. 17, and will be analyzed and considered before the service issues a final rule.
The critique is published online in the journal Conservation Letters.
Congress passed the Endangered Species Act in 1973. The act expanded on previous legislation by providing for the protection of any species in danger of or threatened with extinction throughout all or a significant portion of its range.
The act's language is critical to what follows: In determining whether a species has recovered, the law requires FWS to declare it is no longer endangered in all or a "significant portion of its range." The gray wolf has recovered in the northern Rockies and upper Great Lakes.
The proposed rule, however, discounts the other 85 percent of the wolf's historic range, which stretches across northern states from the west coast through New England and as far east as mid-Texas in the southern half of the country.
"So what the service is saying is that wolves are going to be called recovered in most of the United States despite the fact that very few wolves live outside these two recovered areas," Bruskotter said. "Wherever they are now, that's their range – which means taking the historic and geographic component out of the listing process."
He and colleagues suggest that this practice not only disregards the law, but "specifically creates incentive to destroy habitat in advance of a listing and do things that aren't good for endangered species."
The law also requires the service to consider the "best available science" in assessing whether threats have eased and a species is recovered. Instead of citing the dozens of studies that suggest human support for wolf restoration is high, the service simply ignored this research and claimed that these areas are unsuitable because of human intolerance. When federal protection is lifted, species management falls to the states.
"That process is not the best available science," Bruskotter said.
Bruskotter acknowledged that FWS is under enormous pressure from the opposing sides of a highly contentious fight about wolves: hunters and livestock producers on one side and wildlife advocates on the other. But that pressure doesn't relieve the service of its duty to act on behalf of endangered species as the law requires, he said.
"The law is supposed to help the protected species, not just describe the threats to that species. But to construct this delisting rule, they've had to interpret policy and science in every case in a way that either disregards threats to wolves, or treats them as insurmountable," he said. "They're doing the opposite of what the act requires."
Monday, October 28, 2013
Global warming and forest disturbances may have a silver lining for threatened species of grizzly bears in Alberta, Canada.
In a 10-year study that monitored 112 bears in Alberta's Rocky Mountain region, University of Alberta biologist Scott Nielsen and his colleagues found that warmer temperatures and easier access to food associated with forest disturbances helped the grizzlies to build more body fat, known to increase the chances of successful reproduction for mothers.
The resulting 'silver spoon effect' shows that bears born into these favourable conditions have a head-start in life, said Nielsen, an assistant professor in the U of A Department of Renewable Resources.
"Understanding variations in body size helps us understand what limits grizzly populations," Nielsen said. "We get clues about the environments that most suit grizzlies by examining basic health measures such as body size. A simple rule is, the fatter the bear, the better. Certain environments promote fatter bears.
The findings, published in BMC Ecology, may help influence forest harvest designs to enhance habitat for the Alberta grizzly, which is classed by the Alberta government as a threatened species. Currently there are only about 750 of the bears in the province, half of them adults.
In years when warmer temperatures and less late winter snow brought on earlier spring conditions, the body size of bears as adults was larger. Smaller bears were found in colder and less productive environments or years that were abnormally cool.
"We hypothesize that warmer temperatures in this ecosystem, especially during late winter and spring, may not be such a bad thing for grizzlies," Nielsen said, noting that historically the range for the bears once extended as far south as Mexico and persists today even in the deserts of Mongolia. "That suggests the species won't likely be limited by rising temperatures which would lengthen the growing season and the time needed to fatten prior to hibernation."
As well, bears that used disturbed forest habitats containing a wide variety of stand ages were healthier, Nielsen said.
"The diversity of stand ages in the landscape has a positive influence on body condition because bears are better able to access a wide range of food sources."
Thursday, October 24, 2013
It has long been believed that coyotes were incapable of taking down an adult moose, but researchers have recently discovered that eastern coyotes and coyote × wolf hybrids (canids) have preyed on adult moose in central Ontario. Their findings were published today in the Canadian Journal of Zoology.
Researchers Dr. John Benson, a PhD student in the Environmental and Life Sciences Graduate Program at Trent University when he conducted the research, and Dr. Brent Patterson, a research scientist with the Ontario Ministry of Natural Resources in Peterborough, documented instances where packs of eastern coyotes and coyote × wolf hybrids (canids) were found to have killed moose.
Their study involved live capture of eastern coyotes and eastern coyote × eastern wolf hybrids to deploy Global Positioning System (GPS) radio-collars and take blood samples for DNA analysis. The GPS collars delivered highly accurate locations of the study animals (via satellites or cell towers) so the researchers were able to visit these locations during winter to investigate their activities and document predation patterns. The DNA analysis allowed them to determine whether the animals were coyotes, wolves, or coyote × wolf hybrids.
In the study, four canid packs ranging in size from two to five animals were found to have killed moose. The researchers obtained two accurate ages from moose that were killed by coyotes and/or hybrids: One was very old (20 years) and one was young (20 months). It is believed that younger and older adult moose are probably more vulnerable due to inexperience and deteriorating body condition, respectively.
“Coyotes and coyote × wolf hybrids probably prey on moose opportunistically and only when circumstances are favorable. For instance, when snow is deep and a hard crust forms on top this impedes the ability of moose to travel and gives the lighter coyotes and hybrids an advantage because they can travel on top of the snow,” explained Dr. Benson.
“Additionally, we noticed that some of the moose killed by coyotes and hybrids were on steep slopes that may have slowed the moose and created unstable footing. We also found that some of the moose were killed in areas where medium-sized trees were moderately dense, which may have prevented moose from swinging around quickly to fend off predators attacking from the rear or side.”
“Killing of adult moose by eastern coyotes and coyote × wolf hybrids appears to be relatively rare and probably does not pose a threat to moose populations in central Ontario. However, from the perspective of a pack of coyotes or hybrids, killing even a single moose during a winter is very beneficial and goes a long way towards helping them meet their energetic demands. For instance, a pack of two eastern coyotes spent some or all of 18 days feeding on a moose that they killed.”
The authors do not believe the viability of moose populations in central Ontario is negatively affected by this predation, as recent studies have shown that populations in WMU49 and nearby Algonquin Provincial Park are increasing and that both adult and calf moose survival is relatively high.
This research was a collaborative project between the Ontario Ministry of Natural Resources and Trent University and was conducted in Wildlife Management Unit 49 (WMU49) in central Ontario -- the area between Huntsville, ON and Parry Sound, ON.
The article “Moose predation by eastern coyotes and coyote × wolf hybrids” by John F. Benson and Brent R. Patterson is published today in the Canadian Journal of Zoology.
Monday, July 29, 2013
A new study suggests that the return of wolves to Yellowstone National Park is beginning to bring back a key part of the diet of grizzly bears that has been missing for much of the past century – berries that help bears put on fat before going into hibernation.
It's one of the first reports to identify the interactions between these large, important predators, based on complex ecological processes. It was published today by scientists from Oregon State University and Washington State University in the Journal of Animal Ecology.
The researchers found that the level of berries consumed by Yellowstone grizzlies is significantly higher now that shrubs are starting to recover following the re-introduction of wolves, which have reduced over-browsing by elk herds. The berry bushes also produce flowers of value to pollinators like butterflies, insects and hummingbirds; food for other small and large mammals; and special benefits to birds.
The report said that berries may be sufficiently important to grizzly bear diet and health that they could be considered in legal disputes – as is white pine nut availability now - about whether or not to change the "threatened" status of grizzly bears under the Endangered Species Act.
"Wild fruit is typically an important part of grizzly bear diet, especially in late summer when they are trying to gain weight as rapidly as possible before winter hibernation," said William Ripple, a professor in the OSU Department of Forest Ecosystems and Society, and lead author on the article. "Berries are one part of a diverse food source that aids bear survival and reproduction, and at certain times of the year can be more than half their diet in many places in North America."
When wolves were removed from Yellowstone early in the 1900s, increased browsing by elk herds caused the demise of young aspen and willow trees – a favorite food – along with many berry-producing shrubs and tall, herbaceous plants. The recovery of those trees and other food sources since the re-introduction of wolves in the 1990s has had a profound impact on the Yellowstone ecosystem, researchers say, even though it's still in the very early stages.
IMAGE: This is a grizzly bear in Yellowstone National Park.
Click here for more information.
"Studies like this also point to the need for an ecologically effective number of wolves," said co-author Robert Beschta, an OSU professor emeritus. "As we learn more about the cascading effects they have on ecosystems, the issue may be more than having just enough individual wolves so they can survive as a species. In some situations, we may wish to consider the numbers necessary to help control overbrowsing, allow tree and shrub recovery, and restore ecosystem health."
As wolves help reduce elk numbers in Yellowstone and allow tree and shrub recovery, researchers said, this improves the diet and health of grizzly bears. In turn, a healthy grizzly bear population provides a second avenue of control on wild ungulates, especially on newborns in the spring time.
Yellowstone has a wide variety of nutritious berries – serviceberry, chokecherry, buffaloberry, twinberry, huckleberry and others – that are highly palatable to bears. These shrubs are also eaten by elk and thus likely declined as elk populations grew over time. With the return of wolves, the new study found the percentage of fruit in grizzly bear scat in recent years almost doubled during August.
Because the abundant elk have been an important food for Yellowstone grizzly bears for the past half-century, the increased supply of berries may help offset the reduced availability of elk in the bears' diet in recent years. More research is needed regarding the effects of wolves on plants and animals consumed by grizzly bears.
There is precedent for high levels of ungulate herbivory causing problems for grizzly bears, who are omnivores that eat both plants and animals. Before going extinct in the American Southwest by the early 1900s, grizzly bear diets shifted toward livestock depredation, the report noted, because of lack of plant-based food caused by livestock overgrazing. And, in the absence of wolves, black bears went extinct on Anticosti Island in Canada after over-browsing of berry shrubs by introduced while-tailed deer.
Increases in berry production in Yellowstone may also provide a buffer against other ecosystem shifts, the researchers noted – whitebark pine nut production, a favored bear food, may be facing pressure from climate change. Grizzly bear survival declined during years of low nut production.
Livestock grazing in grizzly bear habitat adjacent to the national park, and bison herbivory in the park, likely also contribute to high foraging pressure on shrubs and forbs, the report said. In addition to eliminating wolf-livestock conflicts, retiring livestock allotments in the grizzly bear recovery zone adjacent to Yellowstone could benefit bears through increases in plant foods.
Wednesday, May 8, 2013
New scientific results show that arctic foxes accumulate dangerous levels of mercury if they live in coastal habitats and feed on prey which lives in the ocean. Researchers from the Leibniz Institute for Zoo and Wildlife Research, Moscow State University and the University of Iceland just published their discovery in the science online journal PLOS ONE.
Mercury is usually transferred across the food chain, so the researchers checked which items were the main source of food and measured mercury levels in the main prey of Arctic foxes.
The scientists compared three fox populations in different environments. Foxes on the small Russian Commander Island of Mednyi fed almost exclusively on sea birds, with some foxes eating seal carcasses. In Iceland, foxes living on the coast ate sea birds whereas those living inland ate non-marine birds and rodents.
In all three environments different levels of mercury were present in their hair. Foxes living in coastal habitats such as Iceland and Mednyi Island exhibited high levels of mercury.
What does this mean for the foxes? Using museum skin samples from the Commander Islands, the researchers could show that the foxes suffered exposure to mercury for a long time. The researchers confirmed that the source of contamination was their food, as they measured high mercury levels in the prey of foxes such as seals and sea birds.
However, the inland Arctic fox populations of Iceland had low mercury levels. Thus, living inland and eating non-marine birds and rodents instead of eating prey that feeds from the sea protected the inland foxes from mercury exposure. This may have health and conservation implications. The Mednyi Island foxes are almost an opposite example to the inland Icelandic fox population. They live on a small island with no rodents or alternative food source to seals or sea birds. They suffered a tremendous population crash and while the population is currently stable, it is very small and juvenile foxes in particular show high mortality rates. Foxes of all ages exhibit low body weight and have poor coat condition.
"When going into this project we thought that an introduced pathogen would explain the poor condition of the foxes and their high mortality but after extensive screening, we did not find anything," says Alex Greenwood, principal investigator of the study. Instead, the researchers began to suspect that something else was at play. "If pathogens were not the cause, we thought perhaps pollutants could be involved. We thought of mercury because it has been reported in high concentration in other Arctic vertebrates also in remote areas and mercury intoxication is known to increase mortality in mammals. As mercury can have negative effects on overall health, particularly in young individuals, and as we knew that Mednyi foxes were exclusively feeding on potentially contaminated sources, we wanted to see whether contamination with mercury depended on feeding ecology and hence might have been the crucial factor for the population decline on Mednyi Island," comments Gabriele Treu, one of the lead authors of the study. As it turned out, the observed high mercury demonstrated a tight association with feeding ecology and geographical distribution of the foxes.
In terms of conservation and long term population health for the entire arctic food chain of carnivores, mercury pollution must be stopped.
Thursday, April 18, 2013
Bear hunters will tell you that a good way to attract a bear is to put out bait. And in 10 states, including Michigan and Wisconsin, that's perfectly legal. Hunting dogs are another useful technique in the bear-hunter's toolkit, and 17 states say that's just fine.
But who else likes bear bait? Gray wolves, that's who. And wolves that are feeling territorial about a bear bait stash can—and sometimes do—kill hunting dogs released at the bait site.
Like most interactions between wildlife and human beings, wolf attacks on hunting dogs illustrate a tangled trade-off: attracting bears for the hunters, attracting danger for their dogs.
Seeking possible ways to reduce potentially lethal encounters between wolves and bear hunting dogs, researchers at Michigan Technological University and the Michigan Department of Natural Resources compared bear hunting practices and regulations in Michigan and Wisconsin.
Joseph K. Bump, a Michigan Tech wildlife ecologist; Dean Beyer Jr. and Brian J. Roell from the Michigan DNR, and students Chelsea Murawski and Linda Kartano report their findings in the April 17, 2013 issue of the Public Library of Science (PLOS) journal PLOS ONE.
The researchers analyzed and compared a variety of factors in Michigan and Wisconsin, from regulations on bear baiting and compensation for hunting dog attacks to statistics such as the ratio of hunters to wolves and percentage of hunters using dogs to hunt bear.
They found that the neighboring states, with similar wolf and bear populations and similar numbers of bear-hunting permits issued per wolf, report dramatically different numbers of wolf attacks on hunting dogs. Wisconsin's relative risk of attack is two to seven times higher than Michigan's.
Bear baiting begins earlier in Wisconsin and lasts longer, the scientists note. "The longer you bait, the more opportunity you provide for wolves to discover and potentially defend bear-bait sites," says Bump. "Most hunters release their dogs at bait sites, and the longer the bait has been around, the more likely hunting dogs are to encounter territorial wolves who have found and are possibly defending the bait. So it appears that baiting is an important factor."
Wisconsin also compensates dog owners $2,500 per hunting dog killed by wolves. In fact, the Wisconsin DNR data show that compensation for wolf attacks on hounds costs the state more than it has spent for wolf attacks on any other category of domesticated animal, including calves, missing calves or cattle.
Michigan does not compensate dog owners for wolf attacks.
"Compensation can have multiple effects," Bump points out. " It is a reporting incentive, but it also creates an incentive for abuse. The net effect of compensation is far from clear, and it is an important factor to study further."
What can be done about wolves that prey on hunting dogs? One quick and obvious response appears to be to reduce the wolf population. In fact, the Wisconsin DNR has announced its intention to reduce the statewide population of wolves by half, from approximately 700 to approximately 350.
Bump and his co-authors recommend more conservation-friendly alternatives such as adjusting baiting regulations to start baiting later and allow it for a shorter time. "If a reduction in depredations is the goal, actions aside from (or in addition to) reducing wolf abundance might achieve that goal," they wrote in the PLOS ONE article.
"If stakeholders are serious about minimizing wolf depredations on bear-hunting dogs, then careful examination of the potentially exacerbating effects of bear baiting would appear to be a good idea," the wildlife ecologist suggests.
Friday, March 29, 2013
A new study from the Wildlife Conservation Society (WCS) and the Nevada Department of Wildlife ( NDOW) has pieced together the last 150 years of history for one of the state’s most interesting denizens: the black bear.
The study, which looked at everything from historic newspaper articles to more recent scientific studies, indicates that black bears in Nevada were once distributed throughout the state but subsequently vanished in the early 1900s. Today, the bear population is increasing and rapidly reoccupying its former range due in part to the conservation and management efforts of NDOW and WCS.__Compelled in part by dramatic increases in human/bear conflicts and a 17-fold increase in bear mortalities due to collisions with vehicles reported between the early 1990s and mid- 2000s, WCS and NDOW began a 15-year study of black bears in Nevada that included a review of the animal’s little-known history in the state.
Over the course of the study, black bears were captured both in the wild and at the urban interface in response to conflict complaints. The captured animals used in the study (adult males and females only) were evaluated for multiple physiological indicators including condition, sex, reproductive status, weight, and age, prior to being released. From the information gathered, the population size in the study area was estimated to be 262 bears (171 males, 91 females).
Confirmed sightings and points of capture from 1988 to present were mapped and presented in the report to illustrate current population demographics, and will be used to inform bear management in Nevada.
“It’s critical to understand the population dynamics in a given area in order to make informed decisions regarding management,” said WCS Conservation Scientist Jon Beckmann. “This includes decisions on everything from setting harvest limits to habitat management to conservation planning in areas where people will accept occupation by bears. We used this long-term study to determine if reported incidences were due to an increasing or expanding bear population, or people moving to where bears are located. The answer is both.”
The study area extended from the Carson Range of the Sierra Nevada eastward to the Virginia Range and Pine Nut Mountains, and from Reno south to Topaz Lake—an area collectively referred to as the Carson front. Because many captures were in response to conflicts, the urban interfaces of cities and towns of the Lake Tahoe Basin were included.
Nevada’s Black Bear History Unraveled
In looking to integrate information on the historical demographics of black bears into their study, the authors found that little published scientific research or data was available and that the species’ history in Nevada went largely ignored until 1987— when complaints arising from sightings and road collisions with vehicles began.
Historical records compiled by retired NDOW biologist Robert McQuivey that included old newspaper articles, pioneer journals dating as far back as 1849, and NDOW records that had long been unavailable, were reviewed and confirmed that black bears were present throughout the state until about 1931. At that point, the authors concluded that “the paucity of historical references after 1931 suggest extirpation of black bears from Nevada’s interior mountain ranges by this time.”
“The historical records paint a very different picture of Nevada’s black bear than what we see today. This new perspective is a good indication of what bear management in this state could involve should the population continue to expand,” said the study’s lead-author Carl Lackey of NDOW.
The authors believe that while over-hunting and conflicts with domestic livestock contributed to the bear’s local extinction in the Great Basin, landscape changes due to clear-cutting of forests throughout western and central Nevada during the mining booms of the late 1800s played an important role as well. But as fossil fuels replaced timber as a heat and energy source, forestry and grazing practices evolved, and reforestation and habitat regeneration occurred in parts of the their former range, the bears rebounded.__Using the information gathered in their review of historic documents, the scientists mapped the distribution of black bears within the interior of Nevada during the 1800s and early 1900s. They recommend that historical range maps for the species in North America be revised to include the information produced as part of the study.__The study, Bear Historical Ranges: Expansion of an Extirpated Bear Population, appears in the current online edition of the Journal of Wildlife Management. Co-authors include Carl W. Lackey of the Nevada Department of Wildlife, Jon P. Beckmann of the Wildlife Conservation Society, and James Sedinger of the University of Nevada, Reno.
Saturday, March 16, 2013
In the southern Rift Valley of Kenya, the Maasai people, their livestock and a range of carnivores, including striped hyenas, spotted hyenas, lions and bat-eared foxes, are coexisting fairly happily according to a team of coupled human and natural systems researchers.
“I wouldn’t call the results surprising,” said Meredith Evans Wagner, a visiting scholar from the University of Florida in the Center for Systems Integration and Sustainability (CSIS) at Michigan State University and part of the research team. “Other research has shown that people and carnivores can coexist, but there is a large body of thought that believes carnivores need their own protected space to survive.”
The paper “Occupancy patterns and niche partitioning within a diverse carnivore community exposed to anthropogenic pressures” was recently published in Biological Conservation. Other authors are Paul Schuette and Scott Creel, of Montana State University, and Aaron Wagner, postdoctoral researcher in the BEACON Center for the Study of Evolution in Action at Michigan State.
The paper’s findings echo results of a study published in PNAS in September 2012 by Jianguo “Jack” Liu and Neil Carter of CSIS: namely that tigers and people are sharing the same space in Chitwan National Park in Nepal, albeit at different times.
Wagner and her colleagues spent just over two years documenting the carnivores of the southern Rift Valley, using motion-detecting camera traps to captures images of the creatures and people using four different areas of land: a conservation area with no human settlements, a grazing area that also had no human settlements, a permanent settlement area, and a buffer zone between the grazing and conservation areas that included seasonal human settlements.
While most of the results were expected – the majority of carnivore photos were taken after dark, most of the larger predators, such as lions and spotted hyenas, tended to be found in the conservation area that didn’t include any human settlements – there were some intriguing results.
“We found that while there were more striped hyenas in the conservation area, there were also striped hyenas in the buffer zone, close to the human settlement area,” Wagner explained. “The hyenas weren’t avoiding that area; they were using the settlement area as a resource in addition to hunting.”
When the Maasai slaughtered an animal for food, they throw the scraps out their back doors, which are at the edge of the buffer zone, where the striped hyenas were happy to eat them.
“Carnivores aren’t a problem for this group of Maasai,” Wagner said. “They’ve made a conscious decision to not hunt carnivores. If one of their livestock is killed by a carnivore, people don’t go out and kill a carnivore in retaliation. It’s a little bit unusual in that way. But in our study, we found that carnivores killing livestock didn’t happen a lot.”
“Wildlife is clearly driven away from the permanent settlement areas," said Aaron Wagner. "But the seasonal human migration out of the buffer zone keeps that area viable for wildlife. Numbers drop when the cattle and people move in, but the striped hyenas seem to have habits that allow them to compensate. They do scavenge around bomas [Maasai settlements] when the pickings are good, but they hunt, too. Even with the people around, there are enough prey left, or enough trickling in from the conservation area, that they have plenty to hunt. More often than not, when following a striped hyena that’s foraging (or playing at a den) at 3 a.m., there’s no indication that people are so close.”
Thursday, January 17, 2013
Dogs and wolves are genetically so similar, it’s been difficult for biologists to understand why wolves remain fiercely wild, while dogs can gladly become “man’s best friend.” Now, doctoral research by evolutionary biologist Kathryn Lord at the University of Massachusetts Amherst suggests the different behaviors are related to the animals’ earliest sensory experiences and the critical period of socialization. Details appear in the current issue of Ethology.
Until now, little was known about sensory development in wolf pups, and assumptions were usually extrapolated from what is known for dogs, Lord explains. This would be reasonable, except scientists already know there are significant differences in early development between wolf and dog pups, chief among them timing of the ability to walk, she adds.
To address this knowledge gap, she studied responses of seven wolf pups and 43 dogs to both familiar and new smells, sounds and visual stimuli, tested them weekly, and found they did develop their senses at the same time. But her study also revealed new information about how the two subspecies of Canis lupus experience their environment during a four-week developmental window called the critical period of socialization, and the new facts may significantly change understanding of wolf and dog development.
When the socialization window is open, wolf and dog pups begin walking and exploring without fear and will retain familiarity throughout their lives with those things they contact. Domestic dogs can be introduced to humans, horses and even cats at this stage and be comfortable with them forever. But as the period progresses, fear increases and after the window closes, new sights, sounds and smells will elicit a fear response.
Through observations, Lord confirmed that both wolf pups and dogs develop the sense of smell at age two weeks, hearing at four weeks and vision by age six weeks on average. However, these two subspecies enter the critical period of socialization at different ages. Dogs begin the period at four weeks, while wolves begin at two weeks. Therefore, how each subspecies experiences the world during that all-important month is extremely different, and likely leads to different developmental paths, she says.
Lord reports for the first time that wolf pups are still blind and deaf when they begin to walk and explore their environment at age two weeks. “No one knew this about wolves, that when they begin exploring they’re blind and deaf and rely primarily on smell at this stage, so this is very exciting,” she notes.
She adds, “When wolf pups first start to hear, they are frightened of the new sounds initially, and when they first start to see they are also initially afraid of new visual stimuli. As each sense engages, wolf pups experience a new round of sensory shocks that dog puppies do not.”
Meanwhile, dog pups only begin to explore and walk after all three senses, smell, hearing and sight, are functioning. Overall, “It’s quite startling how different dogs and wolves are from each other at that early age, given how close they are genetically. A litter of dog puppies at two weeks are just basically little puddles, unable to get up or walk around. But wolf pups are exploring actively, walking strongly with good coordination and starting to be able to climb up little steps and hills.”
These significant, development-related differences in dog and wolf pups’ experiences put them on distinctly different trajectories in relation to the ability to form interspecies social attachments, notably with humans, Lord says. This new information has implications for managing wild and captive wolf populations, she says.
Her experiments analyzed the behavior of three groups of young animals: 11 wolves from three litters and 43 dogs total. Of the dogs, 33 border collies and German shepherds were raised by their mothers and a control group of 10 German shepherd pups were hand-raised, meaning a human was introduced soon after birth.
At the gene level, she adds, “the difference may not be in the gene itself, but in when the gene is turned on. The data help to explain why, if you want to socialize a dog with a human or a horse, all you need is 90 minutes to introduce them between the ages of four and eight weeks. After that, a dog will not be afraid of humans or whatever else you introduced. Of course, to build a real relationship takes more time. But with a wolf pup, achieving even close to the same fear reduction requires 24-hour contact starting before age three weeks, and even then you won’t get the same attachment or lack of fear.”