When do black bears have cubs?

As part of a new to study, researchers at North Carolina State University and the NC Wildlife Resources Commission documented that female black bears (american bear) living within the mountain city limits of Asheville, North Carolina, were taller than expected shortly after their first birthday. These young black bears averaged nearly 100 pounds, almost twice as much as bears living in rural forests.

Surprisingly, some of the city’s young bears also had their first litter of cubs earlier than expected, when they were 2 years old.

The differences between urban bears and rural bears are important for understanding the ecology of black bears living around dense populations, where bears are exposed to vehicle mortality and legal or illegal hunting activities, the researchers said. .

The study was carried out as part of the North Carolina Urban / Suburban Bear Study, initiated by researchers in the state of North Carolina. Chris DePerno, professor of fisheries, wildlife and conservation biology at the State of North Carolina, and Nick gould, postdoctoral researcher at NC State. The work, which was carried out with support from the Wildlife Commission, aims to help us understand bear movements, reproduction, survival and causes of mortality. The goals are to help wildlife managers make science-based management decisions and to help educate the general public about life with black bears.

The Abstract spoke to Gould and DePerno to learn more about their work.

The abstract: When do black bears have cubs?

Gould: Throughout their range, which spans the North American continent, there have been anecdotal cases of black bears breeding in the first year they have separated from their mother. Typically, black bears are born in winter dens from late December to early February. Usually they breed for the first time in summer at 3½ years old, then give birth for the first time around 4 years old.

We have found that some of these Asheville bears breed earlier than expected at 1.5 years and give birth for the first time at 2 years.

AT: What is unique about the way black bears reproduce?

Gould: The black bear is a unique species in that it exhibits delayed establishment. They reproduce during the summer months, but the blastocyst, which is a fertilized egg at a certain stage of development, does not implant in the uterine wall until the fall. This gives bears a chance to feed in the summer when there are summer berries, called soft poles, and in the fall when there are acorns and nuts, called hard poles, which are the main ones. food sources for most black bear populations. The general idea is that if these bears gain enough weight, they are healthy enough to complete and reproduce, and if they do not gain enough weight, for example when food is scarce, they can reabsorb the blastocyst. They save these energy reserves for themselves if there is not enough to carry the pregnancy and give birth.

AT: How long do cubs stay with their mom?

Gould: Black bears give birth to cubs that depend entirely on mom. As the cubs grow, mom will begin to leave the den for short periods of time, but she will not leave the den completely until the cubs have grown up and ready to follow. So, Mom makes short forays to make sure the cubs can move up and down trees, and when the cubs are ready and able to follow Mom, that’s when the family group will leave the den.

Cubs usually stay with mom for about a year and a half. So the moms will give birth in the den and the cubs will stay with the mom for a full year. The cubs will go to den with mom the following winter (as one-year-olds), if she den. If there are food sources available or even warmer temperatures, we have had family groups with yearlings that stay active all winter, with little periods of dormancy. After about a year and a half, during the summer months of June, July, and August, these one-year-old black bears will disperse and leave mom’s parental care.

AT: How big are black bears?

Gould: Throughout our study, we captured and released a few large adult bears. We captured an adult male bear weighing 572 pounds in east Asheville. We captured another 527 pound adult male bear on the Biltmore Estate just behind the mansion. The coastal bear population in North Carolina includes the world record for the largest black bear on record. It weighed 880 pounds and was legally harvested, or hunted, in 1998 in Craven County, North Carolina.

At the start of the North Carolina Urban / Suburban Bear Study, we captured family groups consisting of one-year-olds and a sow, or mother bear. At first we were surprised because we realized that these young bears were quite big. Some of the yearling male bears we captured and released weighed over 200 pounds, and some of the year old bears weighed over 120 pounds. We didn’t expect these young bears to be this big, ranging in age from 1 to 1.5 years old. A healthy rural bear typically weighs between 40 and 75 pounds. This led us to examine whether these young females in particular were able to reproduce at 1 year and a half and then maintain gestation to give birth to cubs that would recruit into the population.

As part of our study, we determined that the young female bears in the Asheville area were twice as heavy as the rural bears involved in the study. At the three wooded rural sites (one in North Carolina and two in Virginia), the average weight of yearling bears was about 23 kilograms, or about 50 pounds. The urban bears in the study were twice as heavy; they weighed an average of 45 kilograms, or about 100 pounds.

AT: Why is this important?

Gould: By bringing all of this data together, we hope that we can help the NC Wildlife Resources Commission to further develop management decisions for black bears, but also the citizens and residents of Asheville can become more educated on how to live. responsibly around bears. We relate what we learned in this first phase of the Urban Bear Study with Bearwise, a public education campaign to educate people about living safely and responsibly with bears.

DePerno: We designed a very comprehensive study to answer many questions that the Commission des ressources fauniques was asking. We get information on calving, movements, dispersal, survival, causes of death, home range, size and age at breeding, which is what this most recent document covers. To truly manage a population of wildlife, you need to understand the life cycle of the species you are working with. We hope to be able to link research and management, which is necessary to help the Commission des ressources fauniques in its management decisions.