John W. Chardine

Changes in Canadian seabird populations and ecology since 1970 in relation to changes in oceanography and food webs.

Systematic monitoring of seabird populations in Canada has been ongoing since the 1920s and the monitoring of diets and other biological indicators of ecosystem change started in the 1970s. Long-te...

Dispersal and distribution of the tick Ixodes uriae within and among seabird host populations: the need for a population genetic approach.

The aim of this study was to characterize the spatial distribution of the tick Ixodes uriae within and among populations of its seabird hosts and to consider the potential insight that could be gained by a population genetic approach to the issue of dispersal of this tick. Analyses of data collected around the Avalon Peninsula, Newfoundland, indicated that both the prevalence and mean abundance of ticks varied significantly among sample locations. Whereas ticks were found on all 4 host species examined (Rissa tridactyla, Uria aalge, Alca torda, Fratercula arctica), infestation prevalence and mean abundance differed among the species. On R. tridactyla, ticks were significantly aggregated at the among-nest scale and nestling infestation was spatially autocorrelated. Conversely, ticks were not aggregated among chicks within nests. These results enabled us to make a priori predictions regarding tick dispersal and host specificity and suggest there may be spatial structure of Ixodes uriae populations at both macro- and microgeographic scales. Investigating the population genetic structure of ticks within and among populations of hosts with different breeding biologies should provide direct insight into the metapopulation dynamics of such a spatially structured system.

The Morphometrics of Migrant Semipalmated Sandpipers in the Bay of Fundy: Evidence for Declines in the Eastern Breeding Population

Abstract. Over 16 field seasons, between 1981 and 2006, nearly 20,000 migrant Semipalmated Sandpipers were captured, weighed, and their bills and wings measured during the fall stopover in the Bay of Fundy. Annual mean bill and wing lengths declined over the course of the study. As eastern Semipalmated Sandpipers have longer bills and wings than those from the west, we interpret the decline to be the result of a reduced proportion of eastern birds in our samples. Semipalmated Sandpiper populations are in decline in North America, and our data suggest that the decline may be more severe in the eastern part of their breeding range. Body mass and size-adjusted mass at the migratory stopover study site have not declined during the study, suggesting that feeding conditions have not deteriorated there. Possibly, differing conditions experienced on the breeding grounds or overwintering areas may explain why eastern populations of Semipalmated Sandpipers may be declining more severely than those from the west.

Origin of Canadian Razorbills (Alca torda) Wintering in the Outer Bay of Fundy Confirmed by Radio-Tracking

Abstract. In the 1990s, flocks of tens of thousands of Razorbills (Alca torda), greatly outnumbering the local breeding population and, so of unknown origin were observed wintering off the island of Grand Manan, Bay of Fundy, Canada. To determine their origin, 39 radio transmitters were deployed on Razorbills at major breeding centers at Corossol Island (n = 10), Québec, the Gannet Islands, Newfoundland and Labrador (n = 15), and a colony near the overwintering area at Machias Seal Island (n = 14) in 2007. From January–March 2008, flights around Grand Manan detected 19 transmitter-fitted birds - twelve from Machias Seal Island, five from Corossol Island and two from the Gannet Islands. The findings confirm that Razorbills making up the wintering flocks off Grand Manan are not only local birds but also birds from major centers of the North American breeding distribution. Therefore, North American Razorbills from all breeding areas are vulnerable to mismanagement of the Bay of Fundy ecosystem, already degraded by over-exploitation and threatened by pollution from a variety of energy developments.