Conservation Implications of Patterns of Horn Regeneration in Dehorned White Rhinos

The demand for rhino horn has led to drastic declines in numbers of rhinos in Asia and Africa. Although all trade in rhino products has been illegal since the mid-1970s, a lucrative illegal market flourishes and poaching continues. Horn removal from African rhinos has been conducted in Zimbabwe, Namibia, and Swaziland to deter poaching. Regeneration of horns following dehorning has created the potential for a sustainable harvest of rhino horn through dehorning programs. Establishment of a regulated legal market for rhino horn has been suggested to help fund rhino conservation programs in African countries. However, evaluation of an economic harvest of rhino horn from dehorning programs has been limited because few data on rates and form of horn regeneration exist. Because rate of horn regeneration will determine the interval at which rhino horns could be harvested profitably, we measured horn regrowth for two white rhino (Ceratotherium simum) populations studied in Zimbabwe between 1991–1995. Measurements of horn sizes were collected before and after dehorning, and mass to volume relationships were calculated. Von Bertalanffy growth curves were used to model horn size and rates of horn regrowth relative to age. Adult males had larger horn bases (p < 0.001) and faster rates of horn regrowth than adult females. Regenerated horn mass for adult males (>1.3 kg/yr) was almost twice the mass of adult females. Based on an economic model for profit maximization, intervals for dehorning range from 1.16 to 1.51 years and vary with both sex and age. We suggest managers use these values as minimum dehorning intervals to balance profits with longer-term management goals. Rates of horn regeneration are likely to be less important than law enforcement in determining the efficacy of dehorning as a deterrent to rhino poaching.     

Health effects of polybrominated dibenzo-p-dioxins (PBDDs) and dibenzofurans (PBDFs)

This article reviews the state of the science regarding the health effects of polybrominated dibenzo-p-dioxins (PBDDs) and dibenzofurans (PBDFs). While thousands of articles have been published on the health effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin and related polychlorinated dibenzodioxins (PCDDs) and dibenzofurans (PCDFs), little is know about the brominated and mixed chloro/bromo homologs. Available literature suggests that brominated compounds have similar toxicity profiles to their chlorinated homologs. However, further research investigating health effects will only be useful if exposure scenarios truly exist. Current exposure data is extremely limited, posing a major data gap in assessing potential risk of these chemicals. The rapid increase in the use of brominated flame retardants has raised the level of environmental concern regarding PBDDs/PBDFs as it is likely that human, as well as wildlife, exposure to brominated dioxins and furans will increase with their use.     

Recycling as a planned behavior: the moderating role of perceived behavioral control

Environment, Development and Sustainability - This study examines the effectiveness of a public service announcement (PSA) video designed based on the theory of planned behavior (TPB) in motivating...     

At-sea activity patterns of breeding and nonbreeding white-chinned petrels <Emphasis Type="Italic">Procellaria aequinoctialis</Emphasis> from South Georgia

Despite the recent burgeoning in predator tracking studies, few report on seabird activity patterns, despite the potential to provide important insights into foraging ecology and distribution. In the first year-round study for any small petrel, we examined the activity patterns of the white-chinned petrel Procellaria aequinoctialis based on data from combination geolocator-immersion loggers deployed on adults at South Georgia. The petrels were highly nocturnal, flying for greater proportions of darkness than any large procellarid studied so far, except the light-mantled albatross Phoebetria palpebrata. Flight bout durations were short compared with other species, suggesting a dominant foraging mode of small-scale searching within large prey patches. When migrating, birds reduced the proportion of time on the water and increased flight bout duration. Activity patterns changed seasonally: birds flew least during the nonbreeding period, and most frequently during chick-rearing in order to meet higher energy demands associated with provisioning offspring. The degree of their response to moonlight was also stage dependent (greatest in nonbreeding, and weakest in incubating birds), a trait potentially shared by other nocturnal petrels which will have repercussions for feeding success and prey selection. For the white-chinned petrel, which is commonly caught in longline fisheries, these results can be used to identify periods when birds are most susceptible to bycatch, and therefore when use of mitigation and checking for compliance is critical.