The conditional benefits of cannibalism for wood frog tadpoles (lithobates sylvaticus)

Wood frog tadpoles have an incredible ability to rapidly adapt to changing conditions, and when population densities become high tadpoles often become cannibalistic. Cannibalism potentially represents an ideal diet by composition, and should be beneficial to the growth and development of cannibalistic individuals. To test the relative efficacy of cannibalism to growth and development we conducted multiple feeding experiments. Results indicate that cannibalism represents a better alternative to starvation and provides some benefit to development and survival of tadpoles over low quality diets. However, cannibalism can be detrimental to tadpole growth and/or develop­ment relative to diets of similar protein content. Additionally, tadpoles raised individually appear to initially avoid consuming the cannibalistic diet, and may continue to do so until they face the risk of starvation. Conversely, when tadpoles were raised in groups providing them with compe­tition, they immediately fed upon the cannibal diet. Our results suggest that competition, rather than dietary quality is likely the driving force behind cannibalistic behaviour unless tadpoles oth­erwise face the risk of starvation

Turnover of passerine birds on islands in the Aegean Sea (Greece)

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73442/1/j.1365-2699.2007.01695.x.pd

Postflood movements and population connectivity in gambusia (Gambusia holbrooki)

A population of the exotic pest fish Gambusia holbrooki inhabiting a drainage channel was sampled regularly to record responses to flooding and subsequent population reestablishment. The flood reduced numbers in the channel to near-zero levels. After remaining very low for 2 months, densities increased steadily through juvenile recruitment and the concentration of fish in drying pools. Tagging revealed that in general, movements between pools separated by only a few metres were relatively limited. There was evidence for habitat segregation and population subdivision, as fish from different pools varied markedly in terms of mean population density, movement behaviour, sex and size composition and juvenile recruitment. The most favoured pool was relatively deep, well lit and had the greatest habitat diversity. Gambusia control measures are likely to be most effective if timed to coincide with floods (which reduce local population densities) and/or droughts (which concentrate fish and allow targeting of source populations)