Because female bears give birth to cubs that are very tiny and helpless, the den where a female has her cub is a critical part of the species’ reproductive biology, as fans of giant panda webcams are well aware. Determining where wild bears give birth, and why in some locations but not others, can be valuable research in support of bear conservation.
One challenge for people planning habitat conservation for Andean or spectacled bears is that we have very little solid information on when and where they give birth. Through our collaboration with the Spectacled Bear Conservation Society (SBC), we’ve been fortunate enough to learn the location of several birth dens in the dry forest of northwestern Peru.
The only other birth den known for this species was found by the Andean Bear Conservation Project in the cloud forest of Intag, Ecuador. Finding birth dens is a challenge, but although knowing where dens are and what they look like is useful, there are many other things that information doesn’t tell us. For example, without additional work, we can’t know whether females are using the only den sites available to them or whether they’re picking dens with particular characteristics.
In the dry forest of northwestern Peru, it’s pretty easy to conclude that female Andean bears must give birth in caves, because no trees in that habitat are big enough to have hollows that a female bear could use as a den. However, it’s a lot harder to determine whether females are selecting as dens those caves with small entrances, or large “bedrooms,” or good viewpoints, or steep slopes, etc.
Although we can get some information from satellite imagery, such as the distance from den sites to areas used by humans, the only way to get a lot of other information is to go into the field and measure caves used by females as dens and compare those measurements to data from caves NOT used by females as dens.
Whimsical “bear” Ambassador Mi Ton Teiow, representing the IUCN’s Bear Specialist Group, and I have visited the northern United States where American black bears spend months in their dens (see Black Bears: A Conservation Success). With SBC’s field team, we’ve now begun collecting information on dens and denning habitat of female Andean bears, which spend much less time in their dens. I hope that after a few more weeks of data collection over hill and under rock, we’ll begin to understand what influences den selection by female Andean bears, allowing better planning for this bear’s conservation.
Russ Van Horn is a scientist with the San Diego Zoo Institute for Conservation Research. Read his previous post, The Fox Stole Our Bread from under the Sapote Tree.