Trends in Wildlife Management and the Appropriateness of Australian University Training

Abstract: That the greatest challenges in conservation are often not technical but rather economic or sociological has been expressed for at least the last 20 years. This raises the question of whether the training offered to tomorrow's conservation practitioners prepares them sufficiently to deal with the human dimensions of conservation. We analyzed 747 papers from seven wildlife management and conservation biology journals to determine the trends in this area of conservation management between 1985 and 1995. We found that over that time the emphasis stayed on single-species issues with a science focus, but there was a marked shift toward conservation biology issues, management-oriented research, and discussion of economic and social factors relevant to management. We also examined the handbooks of 11 Australian universities to analyze the content of 439 compulsory subjects in 12 degrees that we judged could produce wildlife managers. More than 68% of subjects were from a basic science or technology discipline, 16% from resource management, and only 13% from economics, humanities, communications, or planning. Thus, many of the skills required by contemporary wildlife managers must be learned in postgraduate training or on the job. Much of the undergraduate training syllabus, in Australia at least, does not reflect trends in the practice of wildlife management today and will not provide tomorrow's managers with the range of disciplinary understanding required. We were able, however, to identify three types of undergraduate training—ecological system managers, environmental managers, and human system managers—and we found that the curricula in human-system management contained increased emphasis on socioeconomic issues relevant to management.     

Competitor assessment by scent matching: an experimental test

Summary If males assess potential opponents by comparing their odour with that of scent marks in the vicinity (the so called scent matching hypothesis) they should be more reluctant to fight when these odours are the same. Under these circumstances the potential opponent is thus identified as a resource holder (a male monopolising a territory or group of females) that would escalate encounters to defend its resources. We tested this prediction by comparing the fighting behaviour of male house mice, Mus domesticus, when on a scent-marked substrate that matched the odour of an opponent with their behaviour on a substrate that did not match. As predicted, the delay before the first fight was longer and the rate of subsequent fighting lower when the scents matched. This result is consistent with the interpretation that resource holders scent mark to provide opponents with a means of competitor assessment and that they thus reduce the costs of resource defence. Offprint requests to: L.M. Gosling     

Spacing of leks in relation to female home ranges,habitat requirements and male attractiveness in the great snipe (Gallinago media)

Summary In an attempt to examine three main hypotheses on the evolution of leks, data on female home ranges, distance between leks and male site fidelity in the great snipe (Gallinago media) were obtained. In a 30 × 40 km area in central Sweden, the locations of 12 leks were identified. Six were within the study area (7 × 11 km) in which probably all leks were known. In the study area, nearest neighbor distances between leks were longer than the predicted drawing area (diameter of female home ranges plus the detection range of leks). Furthermore, in only 1 of 13 radio-tracked females did the estimated home range enclose many leks. These data do not fit the prediction from the hotspot hypothesis on the dispersion of leks, namely, that the distance between leks should be less than the drawing area and hence an average female home range should enclose more than one lek. The observed distance between leks was about the same as predicted by the female preference hypothesis. This hypothesis also predicts females visit mainly one lek; however, we found they sometimes visit two and nest close to a third. We propose that males may first settle according to hotspot rules, but females will resettle according to preferences for certain males and/or larger leks. In this way some hotspot leks are abandoned, and the distance between leks is increased as males become more tightly clumped. However, when all males and females have settled, the leks still existing would be on hotspots. In the female preference hypothesis, males are assumed to aggregate on leks because females prefer clustered males as they can be more easily compared than if they are dispersed. Alternatively, in the attractiveness hypothesis, it is suggested that females prefer certain males, and hence unattractive males surround the attractive are forced to join leks in order to come close to females. Our data on male site fidelity support the attractiveness hypothesis because successful and dominant males return to the same lek and territory, both within and between years, whereas unsuccessful males move to other leks. Attractiveness of certain males may explain why according to hotspot rules in this species males are more clumped than expected. Offprint requests to: J. Höglund     

Zooplankton abundance and grazing at Davies Reef,Great Barrier Reef,Australia

Zooplankton abundance and grazing on autotrophic and heterotrophic particulate matter were measured along a transect across Davis Reef (18°5S; 147°39E) and in the back-reef lagoon over tidal and diel cycles during austral winter (August 1984). Zooplankton entering the reef from the surrounding shelf waters decreased in abundance over the reef flat, presumably because of predation. Within the reef lagoon, maximum daytime densities of pelagic copepods occurred during high water, suggesting an external input. At night, water-column zooplankton biomass increased by a factor of 2 to 3 due to the emergence of demersal reef zooplankton. Zooplankton grazing rates on heterotrophic particulate matter (bacteria + detritus and Protozoa) compared to phytoplankton were higher on the reef flat than on the fore-reef or lagoon. Within the lagoon, zooplankton grazing rates on heterotrophic material were maximum during high water, coincident with maximum tidal concentrations of particulate organic carbon. The combined demersal and pelagic zooplankton community were often able to crop 30% of the daily primary production by >2µm phytoplankton. However, >50% of phytoplankton biomass was in cells <2µm, presumably unavailable to these zooplankton. Our particulate production and ingestion measurements, together with zooplankton carbon demand extrapolated from respiration estimates, suggest that the zooplankton community of Davies Reef derives much of its nutrition from detritus.Joint contribution from the University of Maryland, Center for Environmental and Estuarine Studies (No. 2015), and the Microbial Ecology on a Coral Reef Workshop (MECOR No. 19)     

Influence of salinity on embryonic development and the distribution ofSepia officinalis in the Delta Area (South Western part of The Netherlands)

The effect of salinity on embryonic development ofSepia officinalis (cuttlefish) in the Delta Area (South Western part of The Netherlands) was investigated in 1988/1989, and compared with data concerning the distribution ofS. officinalis in the three main parts of this area: Oosterschelde, Westerschelde and Grevelingen. Embryos hatched in water collected at Yerseke (Oosterschelde), Vlissingen (Western part of the Westerschelde) and Bommenede (Grevelingen), i.e., at salinity values above 28.1, but not in water sampled at Hoedekenskerke and Hansweert (Middle and Eastern part of the Westerschelde; salinities below 22.0). Under laboratory conditions, using diluted Oosterschelde water, the highest hatching percentages ofS. officinalis were found at salinities above 29.8. Some embryos hatched at a salinity value of 26.5 but no hatching occurred at salinities below 23.9. In embryos exposed to salinity changes during late embryonic development, the developmental rate decreased at salinity values of 28.7 or less. Below 22.4 embryos with morphological malformations were found. It can be concluded that salinity is an important factor limiting the distribution ofS. officinalis in most parts of the Delta Area, with the exception of the Western part of the Westerschelde and the Grevelingen.Contribution no. 489 of the Library of the Delta Institute for Hydrobiological Research     

Diets of piscivorous fishes in a tropical Australian estuary,with special reference to predation on penaeid prawns

The diets of fish from the tropical Embley Estuary in the eastern Gulf of Carpentaria, Australia, were analysed with particular reference to piscivory and predation on juveniles of commercially important penaeid prawns from October 1986 until July 1988. Of the 77 species caught, 52 were piscivorous, and of these 37 ate penaeid prawns. The most numerous piscivores wereScomberoides commersonianus, Arius proximus, Lates calcarifer, Polydactylus sheridani andRhizoprionodon acutus, the first four of which accounted for over 90% of all prawns eaten. Twenty species are commercially important species of prawns. The proportions of penaeids in the diets varied seasonally, according to the density of penaeids in the estuary. The proportion was highest during the pre-wet period (November) and lowest during the dry period (July–August). Predation on prawns was highest in the lower and middle reaches of the river. Estimates of the rates of predation on the two most common juvenile commercial prawns,Penaeus merguiensis andP. semisulcatus, are presented and discussed.     

Aluminum neurotoxicity in mammals

Although aluminum comprises a large percentage of the Earth's crust, it is excluded from body tissues, and especially from the central nervous system. When aluminum is experimentally introduced to the central nervous system, several neurotoxic effects are observed:i.e. neurofibrillary changes, behavioral and cognitive deficits and enzymatic and neurotransmitter changes, as well as certain types of epileptic seizures.The localization of relatively high levels of aluminum in Alzheimer disease, Guamanian amyotrophic lateral sclerosis and Parkinsonism-dementia has led to the implication of aluminum as a pathogenic factor in these diseases. Recent studies have shown that microtubule-associated proteins are part of the paired helical filaments which make up the intraneuronal neurofibrillary tangle. Other studies have identified the protein making the vascular and neuritic (senile) plaque amyloid and located the gene responsible for this protein to chromosome 21.Our electron microprobe analysis studies have not found the levels of aluminum or silicon in either the neurofibrillary tangles or amyloid cores reported elsewhere, nor have the levels of aluminum been elevated in approximately one half of the tangles and plaque cores examined to date.     

Costs and benefits of home range shifts among vervet monkeys (Cercopithecus aethiops) in Amboseli National Park,Kenya

Summary A decline in the density of trees and the deterioration of the habitat of vervet monkeys (Cercopithecus aethiops) in Amboseli National Park, Kenya, have been accompanied by movement of vervet groups into unfamiliar areas. These home range shifts were documented over a period of 26 months. The largest group moved into the home ranges of neighboring groups and acquired more trees, a resource that had become more limited. The groups whose home ranges were encroached upon did not share their home ranges with the intruders, but instead moved into areas that were unoccupied and had a lower density of trees. The largest group was thus more successful than smaller groups in competition for limited resources. For all but one group, movement into new areas was directly associated with the disappearances of female and immature monkeys. Most of the disappearances were attributable to predation. These results suggest that the cost of predation in unfamiliar areas may contribute to the evolution of philopatry in vervets. However, under unstable conditions, resource competition forces these animals to disperse (in groups) despite the high risk of predation. Offprint requests to: L.A. Isbell