Reproductive Ecology and Cub Survival of Florida Black Bears

Abstract: We investigated reproductive ecology and cub survival of Florida black bears (Ursus americanus floridanus) in Ocala National Forest and the adjacent residential area of Lynne, Florida, USA, 1999-2003. We documented production of 81 cubs from 39 litters. Average litter size was 2.08 ± 0.11 (SE) cubs. The mean age of first reproduction was 3.25 ± 0.27 years. Excluding females that reproduced in consecutive years due to litter loss, interlitter interval was 2.11 ± 0.11 years. The mean annual fecundity rate was 0.57 ± 0.06. We used expandable radiocollars to monitor the fate of 41 bear cubs. The probability of cubs surviving to 9 months of age was 0.46 ± 0.09 and did not differ between cohorts or study locations. The most important causes of cub mortality included infanticide and mortality caused directly or indirectly by collisions with vehicles. Our results indicate that reproductive rates of female black bears in the Ocala study area are comparable to those reported for other black bear populations from eastern United States, but cub survival rates are lower than those reported for most black bear populations. Management of Florida black bears should emphasize strategies to reduce the mortality of cubs.     

Ultrastructural Changes and Electrolyte Leakage from Ozone Fumigated Epiphytic Lichens

The ultrastructure of lichens and leakage of electrolytes fromthem were studied to assess the effects of ozone on four epiphytes.Bryoriacapillaris(Ach.) Brodo & Hawksw.,Bryoria fuscescens(Gyelnik)Brodo & Hawksw.,Hypogymnia physodes(L.) Nyl. andUsnea hirta(L.)Wigg. were fumigated with control (<10), 40, 150 and 300ppb ozone in controlled growth chambers for 2 and 4 week periods.The ultrastructural results suggest a direct effect of O₃oncarbon assimilation and storage in these lichens. Both the highconcentrations of ozone (150 ppb and 300 ppb) and longer exposuretime significantly increased starch volume and electron opacityof the pyrenoid matrix in chloroplasts ofU. hirtaandB. capillaris.Furthermore, inU. hirta, cytoplasmic lipid droplets and thenumber of pyrenoglobuli in pyrenoids were significantly increasedat higher ozone concentrations.B. fuscescensshowed little responseto ozone at the ultrastructural level. In bothBryoriaspeciesthe potassium leakage, and inB. fuscescensthe conductivity ofleachate, decreased during 4 weeks fumigation with high concentrations(150 and 300 ppb) of ozone. In most lichens, the total concentrationof K⁺was either unchanged or increased at 150 ppb O₃, suggestingthat no leaching due to membrane damage occurred, but K⁺uptakeby the lichens tended to increase at the concentrations of O₃used.Copyright1997 Annals of Botany Company Epiphytic lichens; Bryoria capillaris; Bryoria fuscescens; Hypogymnia physodes; Usnea hirta; electrolyte leakage; conductivity; potassium; ozone; ultrastructure