Winter Severity Affects Migration and Contaminant Accumulation in Northern Great Lakes Herring Gulls

Abstract

Herring Gull band returns were analyzed from 1962 to 1995. Winter severity was found to affect the winter distribution of Herring Gulls banded as flightless chicks on colonies in northern Lake Huron and northern Lake Michigan. The effects of winter severity were most pronounced in adults, followed by immatures. Little response was observed in juveniles. In adults, the proportion of band returns from southerly locations increased in response to increased winter severity. In general, concentrations of organochlorine contaminants in Herring Gull eggs collected annually from northern Great Lakes colonies increased with winter severity. However, the significance of the relationship between winter severity and organochlorine concentration was compound and colony specific. This probably reflected intercolony differences in winter migration patterns with concomitant differences in contaminant exposure during the overwintering period. With increased winter severity, gulls migrated to more contaminated southerly Great Lakes locations. After spending the winter in these areas the birds returned to their breeding colonies, transferring contaminants to their eggs. The degree to which Herring Gull eggs laid on colonies located in the northern Great Lakes reflect local contaminant bioavailability will be affected by winter severity and overwinter migration patterns.

Dramatic Changes in the Temporal Trends of Polybrominated Diphenyl Ethers (PBDEs) in Herring Gull Eggs From the Laurentian Great Lakes: 1982–2006

“…The highest concentration of BDE-209 measured in 2006 was 20 ng/g ww from Gull Island, Lake Michigan and was comparable to the second highest level measured from Toronto Harbour, Lake Ontario, a highly industrialized/ urbanized region. As discussed earlier, gulls from the northern Great Lakes are known to undertake postbreeding migrations and overwinter close to urban centers (e.g., Milwaukee and Chicago) in southern Lake Michigan (38), which may account for the higher BDE-209 levels in Gull Island and Agawa Rocks egg pools. This may also be the case for gulls from the Chantry Island colony, which are known to winter in more southeasterly locations such as eastern Lake Erie and Toronto Harbour, Lake Ontario (38).…”

“…As discussed earlier, gulls from the northern Great Lakes are known to undertake postbreeding migrations and overwinter close to urban centers (e.g., Milwaukee and Chicago) in southern Lake Michigan (38), which may account for the higher BDE-209 levels in Gull Island and Agawa Rocks egg pools. This may also be the case for gulls from the Chantry Island colony, which are known to winter in more southeasterly locations such as eastern Lake Erie and Toronto Harbour, Lake Ontario (38). (Table 1 and Supporting Information Table S1).…”

Spatial Patterns and Rankings of Contaminant Concentrations in Herring Gull Eggs from 15 Sites in the Great Lakes and Connecting Channels, 1998–2002

“…This was especially true for gulls from sites in Lake Superior, the North Channel of Lake Huron, and northern Lake Michigan. Hebert (1998) also noted that the influence of severe winters would be more noticeable when examining results from studies with infrequent sampling frequencies. Our method of using five years of annual collections in this study (1998)(1999)(2000)(2001)(2002) provides some amelioration for any extremely severe winters and gives a good indication of an average response.…”

“…At both sites, the 5-year average HDD for 1998-2002 (2800 and 3757 HDD, respectively) was lower than during any of the previous four 5-year periods (2980-3317 HHD and 3935-4255 HHD, respectively). Based on Hebert (1998), contaminant levels in eggs collected in warm years from northern colonies would be expected to more accurately represent local contaminant bioavailability. Therefore, the cautionary note expressed by Hebert (ibid) may be of only minimal concern in ranking the 15 sites during the period 1998-2002.…”

“…In a detailed study which showed that in severe winters Herring Gulls from the upper (northern) Great Lakes moved to and/or spent more time in the lower Great Lakes, Hebert (1998) cautioned that contaminant concentrations in these gulls may be influenced by the time spent feeding in the usually more contaminated lower lakes. This has implications for a ranking study such as this one.…”