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Bond A.L.,University of Saskatchewan | Bond A.L.,Environment Canada | Bond A.L.,Center for Conservation Science | Hobson K.A.,Environment Canada | Branfireun B.A.,University of Western Ontario
Proceedings of the Royal Society B: Biological Sciences | Year: 2015

Mercury (Hg) is increasing in marine food webs, especially at high latitudes. The bioaccumulation and biomagnification of methyl mercury (MeHg) has serious effects on wildlife, and is most evident in apex predators. The MeHg body burden in birds is the balance of ingestion and excretion, and MeHg in feathers is an effective indicator of overall MeHg burden. Ivory gulls (Pagophila eburnea), which consume ice-associated prey and scavenge marine mammal carcasses, have the highest egg Hg concentrations of any Arctic bird, and the species has declined by more than 80% since the 1980s in Canada. We used feathers from museum specimens from the Canadian Arctic and western Greenland to assess whether exposure to MeHg by ivory gulls increased from 1877 to 2007. Based on constant feather stable-isotope (d13C, d15N) values, there was no significant change in ivory gulls’ diet over this period, but feather MeHg concentrations increased 45× (from 0.09 to 4.11 mg g-1 in adults). This dramatic change in the absence of a dietary shift is clear evidence of the impact of anthropogenic Hg on this high-latitude threatened species. Bioavailable Hg is expected to increase in the Arctic, raising concern for continued population declines in high-latitude species that are far from sources of environmental contaminants. © 2015 The Author(s) Published by the Royal Society. All rights reserved. Source

Inger R.,University of Exeter | Gregory R.,Center for Conservation Science | Duffy J.P.,University of Exeter | Stott I.,University of Exeter | And 3 more authors.
Ecology Letters | Year: 2015

Biodiversity is undergoing unprecedented global decline. Efforts to slow this rate have focused foremost on rarer species, which are at most risk of extinction. Less interest has been paid to more common species, despite their greater importance in terms of ecosystem function and service provision. How rates of decline are partitioned between common and less abundant species remains unclear. Using a 30-year data set of 144 bird species, we examined Europe-wide trends in avian abundance and biomass. Overall, avian abundance and biomass are both declining with most of this decline being attributed to more common species, while less abundant species showed an overall increase in both abundance and biomass. If overall avian declines are mainly due to reductions in a small number of common species, conservation efforts targeted at rarer species must be better matched with efforts to increase overall bird numbers, if ecological impacts of birds are to be maintained. © 2014 John Wiley & Sons Ltd/CNRS. Source

Bond A.L.,University of Saskatchewan | Bond A.L.,Center for Conservation Science
Waterbirds | Year: 2016

The diets of gulls (Laridae) can have consequences for reproductive success, chick growth, and survival, yet there have been no quantitative assessments in eastern Newfoundland since the early 1970s. The diet of Herring Gulls (Larus argentatus) was examined through regurgitated prey items and pellets on Gull Island, Witless Bay, Newfoundland and Labrador, Canada, in 2012, and compared with similar data from 1970-1971. There was a significant shift in Herring Gull diet composition from blue mussels (Mytilus edulis) and capelin (Mallotus villosus) in the 1970s to garbage and Common Murre (Uria aalge) eggs in 2012. Delays in capelin spawning and the large increase in breeding Common Murres on Gull Island are likely factors influencing Herring Gull diet. Garbage, which includes human food scraps as well as plastic debris, now constitutes the single largest diet item for Herring Gulls, corresponding with a global increase in plastic pollution. The consistently low contribution of fisheries discards suggests that changes in fishing practices and availability of discards are only one possible factor in the Herring Gull decline in Witless Bay. Source

Bond A.L.,Environment Canada | Bond A.L.,Center for Conservation Science | Wilhelm S.I.,Environment Canada | Robertson G.J.,Environment Canada | Avery-Gomm S.,Environment Canada
Waterbirds | Year: 2016

Environmental conditions in eastern Newfoundland have changed considerably since the 1970s, as both bottom-up oceanographic and anthropogenic influences on seabird populations have fluctuated considerably. The diet, reproductive success, and presumably survival of gulls are intrinsically linked to these processes, and breeding populations have declined considerably through the 1980s and 1990s. To assess the populations of breeding large gulls in the Witless Bay Ecological Reserve in eastern Newfoundland and Labrador, Canada, nests were surveyed and clutch size determined for Herring Gulls (Larus argentatus) and Great Black-backed Gulls (L. marinus) breeding on Great, Gull, and Pee Pee Islands in 2011-2012. The total number of breeding gulls of these two species combined decreased by 41% on Gull Island, 78% on Great Island and 51% on Pee Pee Island since 2000. However, the declines differed among habitat type, with modest declines on puffin slopes (-15% to -52%) and the steepest declines in meadows (-70% to -88%), suggesting that large-scale causative factors are not solely responsible for changes in population size. Clutch size did not differ from that in 2000. Differential recruitment among highly philopatric gulls stemming from bottom-up diet-related variation in breeding success may be responsible for different changes in populations among different habitats. Source

Hiley J.R.,University of York | Bradbury R.B.,Center for Conservation Science | Thomas C.D.,University of York
Diversity and Distributions | Year: 2014

Aim: Protected wildlife habitats provide valuable stepping stones for species that shift their distributions in response to climatic and other environmental changes, but they might also aid the spread of invasive alien species. Here, we quantify the use of protected areas (PAs) by both introduced and natural wetland colonists in the UK to analyse patterns of colonization and examine the propensity of invaders to use PAs. Location: United Kingdom. Methods: We calculate PA associations for six species of wetland birds deliberately introduced to the UK and compare these with eight others that have recently colonized the UK naturally. We assess PA associations at three different stages of establishment - first breeding in each county, early establishment of a population (4-6 years after initial breeding) and subsequent consolidation (14-16 after initial breeding) - and analyse changes in PA association over time. Results: Introduced wetland bird species were less associated with PAs than natural colonists at each stage of establishment. During the later stages of colonization, the PA association of introduced species tended to increase. In contrast, natural colonists usually colonized PAs first, and their established populations subsequently spread into non-PA sites. Main conclusions: The United Kingdom PA network did not facilitate the invasion of introduced species during the initial stages of their colonization, but was vulnerable to colonization as populations established. This is in contrast to natural colonists, which are more reliant on PAs during initial colonization but become less dependent as they establish. During a period of rapid environmental change, PAs have facilitated expansions of natural colonists, without acting as the prime sites for invasion by introduced species. © 2014 John Wiley & Sons Ltd. Source

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