Evolutionary lag of predator avoidance by island seabirds, and what happens when naturally occurring colonists become 'invasive'

摘要

‘Lunar phobia’ and avoidance of otherwise bright nights is a characteristic behaviour of Leach’s Storm-petrel Oceanodroma leucorhoa, a small seabird that visits its breeding colonies only at night. This nocturnality and light avoidance, shared by almost all storm-petrels (Hydrobatidae, c. 22 extant species), is generally agreed to be an anti-predator strategy for evading attacks by gulls (Laridae) and other avian predators that have poor night vision (e.g. Watanuki 1986, Warsham 1990). Storm-petrels’ reduced activity on bright nights is thus potentially a classic example of a behavioural adaptation (i.e. a derived character that evolved in response to a speci?c selective agent; Harvey & Pagel 1991) that arose long ago in an ancestral petrel. However, within the storm-petrels generally, nocturnality and light avoidance are not absolutely ?xed as one species, Wedge-rumped Storm-petrel Oceanodroma tethys, long isolated on the remote Galapagos Islands that have never had avian predators present, exhibits entirely diurnal colony attendance. Relaxed selection can clearly lead to the loss of anti-predator behaviour by storm-petrels when it is not needed, but do extreme levels of predation lead to enhanced wariness?