Does one result trump all others? A response to Magurran, Irving and Henderson

Magurran, Irving and Henderson (1997) have reported that a population of European minnows, Phoxinus phoxinus, did not show an obvious behavioural fright reaction when they were presented with conspecific skin extract in a wild situation. Fish from the same population show a strong response when tested in aquaria. From these data the authors conclude that the fright reaction may be contingent on such factors as assessed risk and hunger. From this reasonable hypothesis they progress to the assertion that the Schreckstoff of ostariophysan fishes should not be considered an alarm pheromone. Much of their paper is devoted to arguments supporting their hypothesis that Schreckstoff cannot operate as an alarm pheromone. I argue that it is appropriate and adaptive to respond to alarm signals in a contingent manner, and attempt to answer the various arguments regarding the validity of terming Schreckstoff an alarm pheromone

Alligators in the big city: spatial ecology of American alligators (Alligator mississippiensis) at multiple scales across an urban landscape

Urbanization impacts wildlife, yet research has been limited to few taxa. American alligators (Alligatormississippiensis) are apex predators that have received minimal attention within urban areas. We investigated potential effects of urban land use on alligators through surveys of relative alligator abundance in nine tributaries of the lower St. Johns River within Jacksonville, FL. We then explored the potential effects of urban development on alligator spatial distribution and habitat selection at coarse and fine scales. At the coarse scale, we found no correlation between percent developed land and alligator abundance across tributaries; instead, salinity was the primary driver. However, at the fine scale alligators preferred habitats with more open water and vegetated shorelines and avoided anthropogenic structure. Surprisingly, only one of 93 sighted individuals was an adult. Hunting and nuisance alligator data suggests that adults are relatively rare in Jacksonville because they have been targeted for removal. Thus, smaller alligators still occupy urban habitats because they are not targeted and face no competition from adults. Increasing urbanization and human activity may further degrade alligator habitats and limit the distribution of breeding adults, potentially leading to local population declines