Increase in bear infanticide linked to hunting

Brown bear, Ursus arctos
Alaska Brown Bear, Hallo Bay, Katmai National Park, Alaska. Credit: Wikipedia

(Phys.org) —Studies conducted by multinational government and academic institutes have shown that bear hunting can indirectly increase cub mortality by 81 per cent.

The 21-year study focused on the movements of 180 female Scandinavian brown bears (Ursus arctos) over 13,000 km2 of rolling, forest landscape in south-central Sweden. The research was conducted primarily to investigate the of large, long-lived mammals.

Bear hunting harvests in the area were monitored and the female bears were tagged with radio transmitter implants from 1990 to 2011. During the study, varying degrees of 'hunting pressure' were observed. Bear-hunting season lasts from late August or early September until October 15th or when the quota for a designated area has been reached. Only solitary bears, both male and female, are hunted. Family groups, including solitary cubs and yearlings, are protected from hunting. Female brown bears provide long periods of maternal care (between 1.5 and 4.5 years). The long periods of care reduce the availability of reproductive females.

Unlike their North American counterparts, Scandinavian brown bears have an increased propensity towards sexually selected infanticide (SSI). In cases of limited mating possibilities, it may be advantageous for a member of a sex (usually male) to eliminate the offspring of another member of the same sex to prompt a member of the opposite sex into a reproductive cycle. A female may become receptive only two to four days after losing her young during the .

As expected, the bear population declined during times of high hunting pressure and grew under low hunting pressure . The analysis of the data indicated that the 2 percent decline in fecundity rates (reproductive rates of a population) was greater than expected, estimated after a period of high hunting pressure. Cub survival is important to population growth, with cub mortality reaching 81 percent over the course of the study. The cub loss is mostly attributed to SSI during mating season (mid-May to mid-July). The data showed that without SSI , and with other factors for survival being equal, cub survival would be 81percent higher. This illustrates that other factors besides hunting are responsible for the overall local and that male behaviour appears to have an important effect on population dynamics.

The high hunting pressure resulted in 57 percent of males harvested in 2006–2011, compared with 52 percent in 1990–2005 (low hunting pressure). With more males bears killed, there was a higher likelihood of other male bears encountering cubs and females with cubs that are not related to the male, and thus SSI occurrence increased, causing the larger decrease in bear population.

Other indirect causes for the bear population decline due to hunting are also influenced by the male bear population. In order to counter SSI, female (with cubs) during the mating season avoid good habitats in favour of those in close proximity to humans. This has detrimental effect on the diet of the bear and could subsequently influence female reproductive output, lowering the fecundity.

The study hopes these new findings will be used when establishing hunting quotas and management policies.


Explore further

Bulgaria to ban bear-hunting again

More information: Gosselin J, Zedrosser A,Swenson JE, Pelletier F. 2015 The relative importance of direct and indirect effects of hunting mortality on the population dynamics of brown bears. Proc. R. Soc. B 282: 20141840. dx.doi.org/10.1098/rspb.2014.1840

(c) 2014 Phys.org

Citation: Increase in bear infanticide linked to hunting (2014, November 14) retrieved 19 August 2019 from https://phys.org/news/2014-11-infanticide-linked.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
39 shares

Feedback to editors

User comments

Nov 14, 2014
Most interesting considering there is considerably less bear hunting now than in the past.

Nov 14, 2014
What is it with the incomplete folk who get their kicks by killing?

Nov 14, 2014
What is it with the incomplete folk who get their kicks by killing?
@gkam
easy big guy
it is not just about killing or being incomplete

some people get their groceries this way... so it is a matter of being able to eat or not more-so than getting kicks

for some folk, the primary method of meat is hunting, and it is especially important to get Bear meat for the winter because it has fat, and that is vital to survival to people who live wild in remote areas with no other means of groceries or support

just think about that, eh?

Nov 15, 2014
That might be true for some, and there's no problem with that. But what gkam was talking about were trophy hunters, who kill for "sport".
@sinister
that is something that i can completely agree with... as i despise "sport" hunters
IMHO - i feel (with the obvious exception of humans) that if you kill it, you should eat it

i was trying to clarify that not all hunters are really bad people

i thought the "psychopath" reference was to all hunters
so apologies if it was not

Nov 17, 2014
gkam, is what sinister said accurate? If so I must apologize for the 1 above. Like captain the use of the word psychopath is what led me to think you were attacking all hunters. its a topic im very passionate about and ive seen many anithunters make posts that looked similar to yours so I assumed yours was too. im sorry about that.
captain
that is something that i can completely agree with... as i despise "sport" hunters
IMHO - i feel that if you kill it, you should eat it

agreed, well besides that those type of people are worthy of being called "hunters" imo. killing for the sake of killing and killing to feed or defend yourself are on completely different levels. they are killers, not hunters.




Please sign in to add a comment. Registration is free, and takes less than a minute. Read more