Wildlife and Landscape Science News

Wildlife Populations

> Saskatchewan Piping Plovers: Wrap-up of Seven-Year Field Study

The 2008-2009 fiscal year marks the seventh and final year of fieldwork for Cheri Gratto-Trevor’s study on survival, movements, productivity, and wintering of Saskatchewan piping plovers. This study will improve survival estimates for this endangered species and better inform recovery efforts.

Data suggest that piping plover survival rates appear to be greater than previously published figures. Since these birds live a relatively long time, small changes in survival rate can have a large impact on population models. This means previous models, using lower survival rates, may have overestimated how many chicks need to be produced per pair each year. However, further analyses are necessary to determine exactly what fledging rates are necessary to maintain or increase populations.

Conditions were poor for the birds throughout Saskatchewan in 2008. Big Quill Lake, a very large alkali wetland, was still massively flooded, Lake Diefenbaker, a large reservoir, flooded for the fourth year in a row, and Missouri Coteau areas were dry for much of the summer. Environment Canada scientists carried out most of the 2008 summer fieldwork, identifying uniquely colour-marked birds for survival analyses.

In order to detect birds missed on the breeding grounds, work was also carried out at wintering sites. Scientists searched for marked birds in November 2008 in southern Texas, where most Saskatchewan birds winter. From December 2008 to March 2009 marked birds were identified along the Gulf of Mexico from Florida to southern Texas. Altogether, 119 uniquely marked birds from this study were reported during the winter of 2008-2009, of which 61 per cent had not been seen last summer.

Contact: Dr. Cheri Gratto-Trevor (306) 975-6128

> Boreal Caribou Critical Habitat Science Review

The boreal population of the woodland caribou (also called boreal caribou) was assessed by COSEWIC as Threatened in May 2002. In accordance with the Species at Risk Act (SARA), the Minister of the Environment must prepare a recovery strategy that includes an identification of critical habitat to the extent possible. As part of the effort to identify critical habitat for this Threatened species Environment Canada published the Scientific Review for the Identification of Critical Habitat for Woodland Caribou, Boreal Population (Rangifer tarandus caribou) in Canada on the Species at Risk Public Registry.

Critical habitat identification for the boreal caribou is a multi-layered process that takes into account information at both small and large geographic scales as well as over different time periods. The Scientific Review provides a foundation for understanding whether local populations of boreal caribou are self-sustaining, and outlines an approach for critical habitat identification. However, the Scientific Review does not provide enough guidance to enable the identification of critical habitat under SARA. In particular, further information is being considered to understand the amount, type, and spatial distribution of disturbance that can occur within a local population range while maintaining a self-sustaining population.

The results of the Scientific Review, further scientific work, and knowledge of boreal caribou held by Aboriginal peoples, provincial and territorial governments, and other interested or affected parties, will be considered in order to inform the national recovery strategy for boreal caribou, including the identification of critical habitat.

The proposed national recovery strategy for boreal caribou will be posted on the Species at Risk Public Registry in the summer of 2011 for a 60-day public comment period.

Contact: Stephen Virc (613) 998-6692

Health Effects of Toxics

> Framework for Monitoring Mercury in Atlantic Coastal Ecosystems

Scientists have developed a mercury monitoring program for temperate estuarine and marine ecosystems on the Atlantic Coast of North America. Based on a similar U.S. monitoring plan, this framework is transferable to arctic and tropical marine ecosystems and can help inform decisions on coordinated management, policy, and legislative regulations.

Science-based decision making requires quantitative measurement of mercury in the environment. In order to comprehensively track this volatile element, the framework considers multiple indicators in order to characterize changes in mercury loads in the environment and bioaccumulation in marine food webs. The framework includes monitoring air, sediment, water and a matrix of biotic indicators including invertebrates, fish, birds and mammals.

Although domestic mercury emissions have been reduced by 90 per cent since the 1970s, almost 120 tonnes of mercury are deposited into Canada annually through global atmospheric movements.

Mercury is a risk particularly when it enters aquatic environments, where it converts to its most toxic form (methylmercury) and enters the food web. Humans and wildlife are exposed to methylmercury by eating foods from freshwater and marine environments. This comprehensive approach would enable detection of spatiotemporal trends in mercury, support assessment of toxicity risk for species and food webs, and sustain protection of human and ecological health.

Evers, D., R.P. Mason, N.C. Kamman, C.Y. Chen, A.L. Bogomolni, D.L. Taylor, C.R. Hammerschmidt, S.H. Jones, N.M. Burgess, K. Munney and K.C. Parsons. 2009. Integrated mercury monitoring program for temperate estuarine and marine ecosystems on the North American Atlantic coast . EcoHealth 5 (4): 426-441.

Contact: Neil Burgess (709) 772-4143

> Publications on Environmental Lead

Proceedings of the conference "Ingestion of Lead from Spent Ammunition: Implications for Wildlife and Humans" (Boise State University; 12-15 May 2008) are now available online from The Peregrine Fund, including a keynote paper by Tony Scheuhammer entitled "Historical Perspective on the Hazards of Environmental Lead from Ammunition and Fishing Weights in Canada." 

Scheuhammer’s paper examines research and monitoring efforts, and the subsequent regulations and control measures Canada has taken to reduce lead from spent ammunition in the environment and highlights scientific evidence to identify where current regulations could be improved to reduce even more environmental lead deposition.

Canada prohibited the use of lead shot in 1999, for migratory game bird hunting, but exempted upland game species like American Woodcock, Mourning Doves and Band-tailed Pigeons based on a lack of data for elevated lead accumulation in these species. Since then, several studies have demonstrated that the ingestion of lead shot in upland game birds can be comparable to levels in waterfowl prior to lead shot restrictions. In addition, human consumers of wild game, as well as predators and scavengers, including Golden Eagles, Red-tailed Hawk and Great Horned Owls are at increased risk of poisoning from ingesting upland game birds with embedded lead.

Current non-toxic shot regulations have been very successful; a high compliance has led to a decrease in lead levels by 50 to 90 per cent in Canadian waterfowl. If similar regulations were applied to upland game species, lead accumulation in the environment and in wildlife would be further reduced, Scheuhammer says.

Secondly, the paper discusses regulatory actions taken by other governments to reduce the use of lead sinkers and jigs in fishing gear and Environment Canada’s consideration of broader controls on these products.

Contact: Dr. Tony Scheuhammer (613) 998-6695

> Studies to Determine Pesticide Impact on Endangered Burrowing Owl

The food supply of the endangered burrowing owl in Canada is unlikely to be affected by doramectin, an endectocide widely used to treat pests affecting cattle, even though the compound can reduce the numbers of dung-breeding insects, according to two studies. The studies were triggered by concerns that endectocides may adversely affect dung-breeding insect populations, a source of food for the endangered birds.

Endectocides are used to treat various internal and external parasites in some livestock. After the animal has been treated, the body metabolizes the substance and some of the biological activity can remain in the dung of the treated animal for up to six months. Most animals are treated twice a year, and their dung can be poisonous to insects year round.

The first study monitored insect emergence from cattle dung treated with a recommended topical dose of doramectin. The numbers of insects were reduced for up to 16 weeks, a finding that validated initial concerns. In the second study, regurgitated pellets were analyzed from 206 burrowing owl nests; dung beetles comprised an estimated one-tenth of one per cent of total prey biomass. Burrowing owl reliance on dung beetles is sufficiently low that use of doramectin on cattle is unlikely to appreciably affect the food supply of this species.

Floate, K.D., P. Bouchard, G.L. Holroyd, R.G. Poulin and T.I. Wellicome. 2008. Does doramectin use on cattle indirectly affect the endangered Burrowing Owl? Rangeland Ecology & Management 61 (5): 543-553.

Contact: Geoffrey Holroyd (780) 951-8689

> Seabirds: Non-polybrominated Diphenyl Ether Flame Retardants in the Eggs of Great Lakes Herring Gulls

According to a recent study, the appearance of non-polybrominated diphenyl (PBDE) brominated flame retardants (BFRs) in female herring gulls and their eggs over the past 25 years indicate that there has been a continual presence, exposure and bioaccumulation of several BFRs of emerging environmental importance in the Great Lakes.

Several non-PBDE BFRs were found in herring gull eggs collected from seven colonies across the Great Lakes but were found to vary in their levels. While some contaminants are becoming more prevalent over time, others are present at low levels. Of note was decabromodiphenylethane (DBDPE), which was not detected in any egg pools collected prior to 1996, but was present starting in 2004 and for some colonial sites at concentrations of several hundreds of parts per billion.

The production and use of PDBE BFR alternatives have been on the rise, although their assessment in environmental samples is largely understudied the study noted.

The study used the specimen bank at the National Wildlife Research Centre in Ottawa which houses over 65,000 biological samples and half a million sub-samples so that scientists can investigate environmental trends and conduct retrospective analysis as new environmental concerns, like non-PBDE BFRs, arise. The availability of the specimen bank helped scientists first discover the presence of PBDEs and dioxins in the Great Lakes.

Gauthier, L.T. (former MSc student), D. Potter, C.E. Hébert and R.J. Letcher. 2008. Temporal trends and spatial distribution of non-polybrominated diphenyl ether flame retardants in the eggs of colonial populations of Great Lakes herring gulls. Environ. Sci. Technol. 43 (2): 312-317.

Contact: Dr. Robert Letcher (613) 998-6696

> Arctic Warming and Impact on Sea Ice and Diet Change on Contaminant Dynamics in Polar Bears

Polar bears from western Hudson Bay in the Canadian sub-Arctic are experiencing a shift in diet related to sea ice break-up date, one effect of Arctic warming, that is contributing to an increase, or change, in the levels of some persistent and bioaccumulative contaminants from this subpopulation, according to a collaborative study between Environment Canada and the Department of Environment, Government of Nunavut.

This study reports the first known evidence that earlier sea ice break-up over the past 18 years is a contributing factor to a diet shift that can result in a greater exposure to PCBs, organochlorine pesticides and PBDE flame retardants.

To identify the sources of these contaminants to polar bears, the team measured fatty acids and carbon isotopes as dietary tracers. Over time, where the sea ice broke up at an earlier date, the dietary tracers showed that polar bears ate more open-water species such as harbour and harp seals instead of ice-associated species such as bearded seals. Harbour and harp seals accumulate higher contaminant levels than bearded seals because they eat higher on the food chain, with a diet richer in fish.

This paper is the central topic of a news item in the journal Environmental Health Perspectives that discusses the study’s implications on the traditional subsistence diet of hunters.

McKinney, M.A. (PhD student), E. Peacock and R.J. Letcher. 2009. Sea ice-associated diet change increases the levels of chlorinated and brominated contaminants in polar bears. Environ. Sci. Technol. 43 (12): 4334-4339.

Contact: Dr. Robert Letcher (613) 998-6696