—Data on Snowy Owl ( Nyctea scandiaca) reproduction on Wrangel Island were collected for six seasons fr om a total of 423 nests. Nest densities ranged fr om 0.15 to 0.40 nests/km 2. Mean clutch size for all 6 years was 6.5 (fr om 5.3 to 8.4) being significantly higher during low lemming season (7.17) (N = 29) than for peak lemming season (6.0, p < 0.001). Clutch size corr elated with weather co...

Habitat use has important consequences for avian reproductive success and survival. In coastal areas with recreational activity, human disturbance may limit use of otherwise suitable habitat. Snowy plovers Charadrius nivosus have a patchy breeding distribution along the coastal areas on the Florida Panhandle, USA. Our goal was to determine the relative effects of seasonal human disturbance and ...

In order to better understand the nature of disturbances to wintering snowy plovers, I observed snowy plovers and activities that might disturb them at a beach near Devereux Slough in Santa Barbara, California, USA. Disturbance (activity that caused plovers to move or fly) to wintering populations of threatened western snowy plovers was 16 times higher at a public beach than at protected beache...

A problem confronting Snowy Owls (Nyctea scandiaca) in their southern incursions is the shortage of food. This difficulty is raised by the presence of other raptors that feed on small mammals. This note shows how little food is found by migrant Snowy Owls and indicates a complex temporary ecological solution. At Tatoosh Island, Washington (48”24’ N, 124” 44’ W) on 25 November 1973, we observed ...

Matrix model analysis of a coastal northern California subpopulation of the western snowy plover (Charadrius alexandrinus nivosus) Abstract Shorebirds are increasingly threatened by introduced predators, invasive grasses, and human disturbance. Matrix models can be used to predict population growth and assess management options. The Pacific coast population of the western snowy plover, Charadri...

Habitat selection during the breeding season has important consequences for reproductive success and, in seasonal and heterogeneous environments, most likely occurs on several temporal and spatial scales. I examined several possible topographical, substrate and vegetation, as well as anthropological effects on snowy plover (Charadrius alexandrinus) habitat selection across pre-breeding and bree...

To study the susceptibility of wading birds to eastern equine encephalitis (EEE) virus and to determine their potential as reservoir or amplifying hosts, fledgling glossy ibises (Plegadis falcinellus) and snowy egrets (Egretta thula) were captured in New Jersey (USA) and shipped to Colorado (USA) where they were experimentally inoculated with EEE virus. All 16 snowy egrets and 14 (93%) of 15 of...

The wind’s effectiveness was compared in different points of a watershed using a quantity called The Wind Shelter Index.The wind’s effectiveness was compared in different points of a watershed using a quantity called The Wind Shelter Index. It is necessary to choose a distance called the effective distance in the process of this index determination. The criterion already used for this purpose w...