Among‐colony synchrony in the survival of Common GuillemotsUria aalgereflects shared wintering areas

Abstract

Spatiotemporal variation in survival may be an important driver of multi-population dynamics in many wild animal species, yet few scientific studies have addressed this issue, primarily due to a lack of sufficiently comprehensive and detailed datasets. Synchrony in survival rates among different, often distant, subpopulations appears to be common, caused by spatially correlated environmental conditions or by movement of animals from different sites such that their ranges overlap. Many seabird populations are effectively isolated during the breeding season because colonies are widely separated, but over the winter, birds disperse widely and there may be much mixing between different populations. The non-breeding season is also the period of main mortality for seabirds. Using mark-recapture and ring-recovery data, we tested for spatial, temporal and age-related correlations in survival of Common Guillemots Uria aalge among three widely separated Scottish colonies that have varying overlap in their overwintering distributions. Survival was highly correlated over time for colonies ⁄ age-classes sharing wintering areas and, except in 2004, was essentially uncorrelated for those with separate wintering areas. These results strongly suggest that one or more aspects of the winter environment are responsible for spatiotemporal variation in survival of British Guillemots, and provide insight into the factors driving large-scale population dynamics of the species.

Skipped breeding in common guillemots in a changing climate: restraint or constraint?

“…Nonetheless, skipping was more frequent in years where SST in their wintering area in the southern/western North Sea were high the preceding winter and also the one before i.e., ca.15 months prior to the breeding season. Ringing recoveries and tracking studies indicate that guillemots from the Isle of May disperse widely throughout the North Sea during the winter months, with the core of the winter distribution centering on the southern and western North Sea (Reynolds et al, 2011;Harris et al, in press). North Sea temperatures have increased gradually over the past several decades in line with rising global air temperatures, but the rates of warming observed in the southern North Sea (most of which is <50 m deep) are among the highest documented anywhere in the world (Rayner et al, 2003;Heath et al, 2012).…”

“…While they could adjust investment in the single egg or chick in response to changes in the environment (e.g., Erikstad et al, 1997), not breeding in the first place may be less costly in terms of future fitness. Common guillemots from our study colony spend the winter months in the shallow southern North Sea (Reynolds et al, 2011), an area that has experienced extreme local warming rates over the past 30 years (Rayner et al, 2003). Previous studies of common guillemots have established links between demographic rates or phenology and marine climate experienced both locally around the breeding colony and further afield in the wintering area (e.g., Frederiksen et al, 2004a;Sandvik et al, 2005;Votier et al, 2008;Reed et al, 2009).…”

“…Guillemots disperse widely outside of the breeding season and ringing recoveries and data from geolocators indicate that in December and January adult guillemots from the Isle of May are concentrated in the southern North Sea (Reynolds et al, 2011;Harris et al, in press), although birds are also known to attend the breeding colony intermittently throughout the non-breeding season Wanless, 1989, 1990). Weather or oceanographic conditions experienced in the winter range may therefore have a direct or indirect effect on annual breeding propensity via cues or constraints.…”

Confusion Reigns? A Review of Marine Megafauna Interactions with Tidal- Stream Environments

“…However, it is unclear what the exact cause of this decline might be . A decline in 0-group size-at-date is presumably due to changes in hatch or spawning dates, or changes in growth rate (Frederiksen et al 2011). However, there is no evidence of trends in hatch dates on the Scottish east coast (Heath et al 2012a), so the proximate cause for the decline in 0-group size-at-date must be a change in growth rates.…”

“…Indeed, reduced overwinter survival rates for breeding Atlantic puffins on the Isle of May in 2006-2007 and 2007-2008, combined with an increase in immature mortality , was sufficient to explain a 30% reduction in breeding population between . Synchrony in guillemot survival rates from different colonies around Britain, that share overwintering areas, provides further evidence that climate could be the key determinant of mortality (Reynolds et al 2011). …”