Natural History and Ecology

Transcription

1 Natural History and Ecology The Florida Black Bear 3 Species of Bear in North America David Tucker Subspecies of Ursus americanus The American Black Bear The Florida Black Bear Brown/Grizzly Bear The Louisiana Black Bear Polar Bear U. a. floridanus U. a. americanus Black Bear U. a. luteolus Southeastern Subspecies Ranges Florida All Florida bears are black Males average 300 lbs, females 180 lbs Florida bears are no smaller than northern bears U. a. americanus U. a. floridanus U. a. luteolus 1

2 are plantigrade: walk on surface of entire foot Hardwood hammocks Habitat Use Cypress swamps and forested wetlands (prefer for rest and feeding) Pine flatwoods Sand pine scrub Diet of Black Diet Okefenokee-Osceola study: ,160 bear scats Sweet gallberry, saw palmetto and grapes (soft mast) accounted for majority of summer diet. Black gum, palmetto fruit and acorns (hard mast) dominant in fall diets. Osceola bears exploited corn from deer feeders, but showed preference for natural foods when abundant. Variation in seasonal abundance of food, especially black gum, affects reproduction, movements and denning. 1995: black gum shortage: 1 of 15 radio-collared females had cubs 1996: black gum abundant: 21 of 22 females produced cubs Annual home range size for Okefenokee females: 56 sq. kilometers (22 square miles) Between 1998 and 1999, fall home range size increased from 14.5 sq. km to 78 sq km for females in Okefenokee. Black gum production was high in 1998 but low in But abundant palmetto crop in uplands in Annual home range size for Osceola females: 30 sq. kilometers (11.5 square miles) Corn feeders: enabled Osceola bears to meet nutritional needs in much smaller areas. 2

3 Most fetal development occurs during last 6-8 weeks. Reproduction Sexually mature 3-4 yrs Mating occurs in the summer Seasonally constant estrus: remain in estrus until bred Cubs weigh only grams at birth, extremely small % of female body weight. Delayed implantation: blastocysts float free in uterus and do not implant until Nov-Dec. Cubs born in winter dens: late January early February Stay with mom through summer and fall and may den with mother during the next winter. Induced ovulators Long-period of dependency: bred every other year. Mean litter size = 2 Dens Usually bird nest style Occasionally in burrow or stump Cubs are fully furred and weigh a kg or more at 40 days of age Cub survival study ( ): Ocala National Forest 38 radio-collared cubs 3

4 Cub survival data for north-central Florida Survival probability of cubs to 9 months of age: 46% Maternal experience: at 25 weeks after collaring 79% of cubs of first-reproducing females had died 42% of cubs of multiparous females had died Litter size, cub weight and sex of cubs did not appear to affect survival in this study. Timing and Causes of Cub Mortality Most vulnerable age: months: 68% of mortality occurred during this age interval. Cannibalism: most important mortality factor Resident male bears were the predators 3 of 7 attacks on a family occurred at natal dens 2 instances: females killed as well Malnutrition: orphaned cubs Human/Bear Interactions Direct Impacts: Human Impacts Mortality roadkill and illegal kill Habitat loss Indirect Impacts: Habitat fragmentation and isolation Behavioral changes Avoidance of areas heavily used by humans Attraction and habituation Historic Black Bear Range Current Black Bear Range 4

5 Florida Bear Range Florida s Growing Human Population Human Population 18 million residents 80 million visitors yr Future Projections 20 million residents by the year 2020 Continued development Florida s Growing Human Population Bear-Related Calls Received by FWC Development Urban sprawl into historically remote areas New residents who are unfamiliar with Florida s native wildlife Human-Bear Interactions in Florida (N = 8,371) Threatened/Attack Animal (2%) Misc./Unknown (2%) In Building (2%) Threatened Human (1%) Beeyard (3%) In er (4%) Killed Animal (5%) The Ecology of the Florida black bear (Ursus americanus floridanus) at the urban-wildland interface of Ocala National Forest Data at the interface were virtually nonexistent May serve as population sinks Injured / Sick (5%) In Area / Yard (40%) are able to coexist if tolerated Carcass (7%) Property or Crop Damage (8%) In Garbage (21%) 5

6 Morphological data Methods in the Lynne and Paisley areas are captured using culvert traps and Aldrich spring activated leg-snares in the forest are monitored as controls Immobilized with Telazol Gardens Field work Bird ers Diel monitoring Mortality is documented Fecundity is determined Compost Piles HUMAN FOOD SOURCES Bear movements and activities are monitored using portable equipment and aerial telemetry Weight and measurements are taken Pre-molar is extracted for age determination Hair sample/ blood are collected for genetic data Upper lip is tattooed for permanent identification Both ears are inserted with plastic identification tags VHF radio collars are fitted Fruit Trees Garbage Livestock CAUSE Back Yard Grills BEAR CONFLICTS! Food Pantries Pet Food Freezers Pet Food and Other Items Unprotected Garbage 6

7 Back Yard Bird ers Property Damage by Photo by Milt Fox Photo by Milt Fox in Town Habituation and Loss of Fear Management Options that consistently feed from human food sources will associate people with food and lose their natural fear of humans. Nuisance problems quickly follow. This pattern is difficult to break and property damage often results. Management action may become necessary. Photo by Milt Fox Relocating nuisance black bears Technical Assistance Trap and relocate return home no remote areas left moving problem to new area Euthanasia may become necessary to protect human safety 41 bears (33 males, 8 females) translocated to Ocala Nat Forest 19 bears (17 males, 2 females) engaged in a nuisance event at least once post-release and 14 engaged in nuisance events more than once. 13 bears returned to their original capture site (home), and bears moved < 64 km (40 miles) from original capture site were more likely to go home. 7

8 13 bears stayed in ONF The Key to Avoiding Conflicts 15 bears left ONF but did not go home (4 traveled widely: km or miles) Survival estimates for translocated bears no different than those of resident bears in ONF. Is Making Human Food Sources Unavailable to Problems did not go away for homeowners 19 had another conflict within a year 7 had another conflict within a month Focus on community education and outreach and other nonlethal management techniques to reduce bear-human conflicts. Bear Resistant Garbage Containers Electric Fencing Bear Roadkill Locations