Incorporating behavior-based indices of connectivity into spatially explicit population models

Measuring connectivity in fragmented landscapes remains a central problem in ecology. Connectivity metrics range from descriptors of landscape structure to direct observations of a species’ ability to move to and colonize a forest patch. We constructed individual-based spatially explicit population models for a guild of forest rodents in Indiana to test the ability of structural and actual, or behavioral, measures of connectivity to predict patch and landscape occupancy and abundance. Model accuracy was assessed using comparisons with data from trapping studies. Predicted abundances within patches correlated with empirical data for five out of six species, but predicted patterns of patch occupancy corresponded with observations for only one species. Discrepancies may be due to inaccurate parameter values or the absence from the models of ecological processes such as conspecific attraction and competition. Nonetheless, the models demonstrated the utility of patch immigration as a measure of connectivity in explaining population abundance in fragmented landscapes. We discuss potential methods of collecting these behavior-based data. </jats:p

Acorn germination is not enhanced near cache sites relative to random locations

Acorns produced by oak (genus Quercus L.) trees are eaten by numerous wildlife species, many of which may also contribute to oak regeneration by dispersing acorns to favorable microhabitats. According to the directed dispersal hypothesis, seed dispersal agents may preferentially move seeds to locations that favor seedling establishment. As a case study of the directed dispersal hypothesis, we tested the hypothesis that vertebrate scatterhoarders preferentially cache acorns in locations where conditions favor germination. We planted acorns within 0.3 m of known cache sites (cache plots) and at paired random plots that were located at equal distances from the acorn source. We then monitored germination, seedling emergence, and growth over the first year. Acorns near actual cache sites germinated at lower rates than acorns in random sites, the opposite of what would be predicted by the directed dispersal hypothesis, but insufficient seedling survival prevented statistical analysis of survival and growth. These results do not support the directed dispersal hypothesis with regard to the microhabitat at cache plots, and do not address the effects of seed burial or the potential for longer term positive effects on survival of germinated seedlings. </jats:p

Core area and centre of activity of maned wolves, Chrysocyon brachyurus (Illiger) (Mammalia, Canidae), submitted to supplemental feeding

Based on the finding of remains (tracks, scats, and hairs), an analysis was made of the core area and centre of activity of maned wolves, Chrysocyon brachyurus (Illiger, 1815), living in a private natural reserve in which ecotourism activities are developed and these animals are daily fed bovine meat. A total of 465 samples of remains were recorded. Using the fixed kernel method, the area encompassing all samples recorded was estimated at 25.7 km², yet 50% of all samples were found in an area of only 1.5 km², representing 5.8% of the total area covered. For estimating the core area of the animals, the frequency of occurrence of the samples was determined by superimposing a 50 x 50 m cell grid over a map of the area encompassing all recorded occurrences. Based on the cells containing more than six occurrences, the animals' core area was 0.99 km², which included the place where the animals are fed. The centre of activity was located only 0.50 km from this place. The high negative correlation (r = -0.93, p < 0.05) between the densities of the recorded occurrences and the distances from these to the sanctuary indicates that the core area and centre of activity are conditioned by artificial feeding.<br>A área central e o centro de atividade de lobos-guará, Chrysocyon brachyurus (Illiger, 1815), foram determinados através de seus vestígios (fezes, pegadas e pêlos) em uma reserva natural particular, onde esses animais estão sujeitos à alimentação artificial e sofrem influência de atividades turísticas. No total, foram registrados 465 vestígios, sendo que 65,8% corresponderam à estação seca. Através do método Kernel fixo, a área compreendida por todos os vestígios foi de 25,7 km², sendo que 50% encontravam-se em uma área de apenas 1,5 km², o que representou 5,8% do total da área amostrada. A área central de atividade dos animais foi obtida pelo cálculo da freqüência dos registros dos vestígios através da sobreposição de uma quadrícula subdividida em células de 50 x 50 m sobre a área que abrangia todos os registros. Considerando as células com mais de seis registros a área central de atividade atribuída aos animais foi de 0,99 km², o que abrangeu a sede da reserva onde os animais são alimentados. O centro de atividade localizou-se somente a 0,50 km da sede. A alta correlação negativa (r = -0,93, p < 0,05) obtida entre as densidades dos registros e suas distâncias até a sede da reserva indicaram que o centro de atividade e o tamanho da área de maior intensidade de uso são condicionados pela alimentação artificial