The incidence of abnormalities in the fire-bellied toad, Bombina orientalis, in relation to nearby human activity

Declines in amphibian populations are occurring worldwide, and have been attributed to many factors, including an­thropogenic environmental changes. One of the ramifications of such declines is abnormalities in many amphibian spe­cies. A strong association has been detected between human activities and abnormalities in amphibian populations, but studies on this association are largely focused on lentic species. In this study, it was analyzed whether the degree of local human activity was associated with the rate of abnormalities in Bombina orientalis which inhabited lotic environments. We found that the proportions of abnormalities in wild populations of B. orientalis increased, when i) the closest human land use was located within 100 m from the frogs’ habitat, and ii) the proportion of human land use within a 300-m radius was high. Our findings suggest that human activity has a negative impact on the fitness of nearby amphibian populations, and that wild populations very close to human-induced disturbance are affected

Prey with hidden colour defences benefit from their similarity to aposematic signals

Some camouflaged animals hide colour signals and display them only transiently. These hidden colour signals are often conspicuous and are used as a secondary defence to warn or startle predators (deimatic displays) and/or to confuse them (flash displays). The hidden signals used in these displays frequently resemble typical aposematic signals, so it is possible that prey with hidden signals have evolved to employ colour patterns of a form that predators have previously learned to associate with unprofitability. Here, we tested this hypothesis by conducting two experiments that examined the effect of predator avoidance learning on the efficacy of deimatic and flash displays. We found that the survival benefits of both deimatic and flash displays were substantially higher against predators that had previously learned to associate the hidden colours with unprofitability than against naive predators. These findings help explain the phenological patterns we found in 1568 macro-lepidopteran species on three continents: species with hidden signals tend to occur later in the season than species without hidden signals