One of the AGFC’s Most Valuable Tools
By Clay Newcomb
This article describes a den study that the author went on and the value of the biological data gathered. Big Brenda, the 300 lb sow, had two chocolate colored cubs that aided the biologist conclusion that reproduction is back up the Ozarks.
As we neared the den site, Myron Means, the AGFC’s bear coordinator, told us the big sow bear named Brenda was likely awake and that our approach would need to be as quiet as possible. It was mid February, the sun was shining and temperature was near 50 degrees. Unbeknownst to many, black bears don’t actually hibernate. Their body temperature remains relatively constant through their winter slumber and they often awake, and even leave the den on warm winter days to forage.
As we approached the den, which was located on the north face of steep oak hickory ridge, AGFC biologist Kevin Hisey went ahead of us and ducked his head in a 2 foot wide dark hole in a jumble of mossy Ozark limestone. When he arose from the darkness, in a nodding whisper he said, “She’s in there, she’s wide awake, and she is big. ” Mryon waved me over and said, “Take a look at her. ” To which I replied, “You sure she won’t mind that flash light in her eyes? ” To be honest, I was slightly reluctant to put my head in a hole with a fully awake, non tranquilized sow bear with cubs. However, reluctance was quickly replaced with a slow ascent as I lowered my head straight down into the darkness. As I clicked on my flashlight, my gaze was intercepted by the dark beady eyes of big Brenda. At a mere 6 feet from my face, there she lay with two chocolate cubs suckling underneath her 300 lb frame.
The AGFC annually conducts over 60 den studies, spread over all the regions of Arkansas that hold bear. These studies are based around radio collared females that have been captured and are tracked yearly by the AGFC. These studies are designed to collect biological data of the reproduction efforts of the sow bears in the state. The cubs are counted, aged, sexed, weighed and measured in this study. This data is some of the most important data gathered about bear in Arkansas. From these studies biologist can determine the overall heath of the black bear population in Arkansas. If sows in a particular region have a low number of cubs, or none at all, conclusions about why, and long term effects of the low reproduction are made. In the same way, if the sows have an above average number of cubs and opposite conclusions are drawn, the recommendations for the coming hunting seasons will be affected.
Typically, regional mast production, both hard and soft, greatly affect bear reproduction. Myron said, “The easter freeze of 2007 killed all the summer and fall mast, and we still are seeing the effects of it in 2010. ” This statement can be explained by a phenomena called ‘Delayed Implantation’. This biologically master minded breeding strategy is when the fertilized egg doesn’t attach to the uterine wall until the females body tells her that she has the excess fat reserves to nurture cubs through the winter. Bears breed in May, June and early July but the egg is stored until November when the a nutritional assessment is complete. If the female is in poor health because of a poor mast crop, she will not give birth or perhaps give birth to a below average number of cubs. If she is in excellent health, she may give birth to an above average number of cubs. Bears in the Ozarks have an average of 2 cubs per litter while Ouachita sows average of 3 cubs per litter - there is no clear cut explanation for this, but likely habitat is the issue. Bears have a 60 gestation period and give birth in the winter den in early to mid January. New born bears are hairless, quite underdeveloped and weigh under 1 pound.
The above scenario is not where we are at in Arkansas, but the AGFC is keeping a close watch on reproduction and hunter harvest. In the fall of 2009, 530 bears were harvested in Arkansas. This beat our record of harvest of 400 bears in 2008 by 130 animals! This accompanied by two years of poor reproduction, particularly in the Ozarks, gives the AGFC reason to keep a close watch. The AGFC would like to see approximately 10% of the bear population harvested annually. They estimate that the growth rate of our population is 10%, so by harvesting this number we can keep the population stable. In the regions of Arkansas where bears are - primarily the Ozarks, Ouachitas and in the lower White River drainage, the AGFC’s goal is to keep the population stable. In some regions in the Gulf Coastal Plain of southern Arkansas, particularly Felsenthal National Wildlife Refuge, recent reintroduction efforts have been underway in attempt to establish a population. At the current time, approximately 50 animals have been captured in from the White River region and relocated to Felsenthal.
On this den study in the Ozarks, Brenda the sow had two healthy chocolate colored cubs. The cubs were approximately 7 weeks old and weighed just over 4 pounds. Myron stated, that from this study and the other studies they have conducted in the winter of 2010, that bear reproduction was back up to historical averages - except in extreme northern Arkansas. In these regions the ice storm of January 2009 hit the mast crop hard and made reproduction in these areas low. In conclusion, these den studies are some of the most important studies that the AGFC does. The biological data gather aids them making hunting regulations for the coming season and getting an overall feel of the heath of the bear population in Arkansas.
See all the photos from this trip in our photo gallery under Den Study 2010.