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Importance to Seabirds

Seabirds
Rhinoceros Auklet
Cassin's Auklet
Tufted Puffin
Common Murre

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Climate Change
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Scott Islands Research Station

Research

The wildlife and plants of the Scott Islands were first studied and recorded by the BC Provincial Museum (now the Royal British Columbia Museum) in the 1950s. In the 1970s, biologists with the Canadian Wildlife Service (CWS) began integrated studies of Triangle Island's seabirds. The research consisted of pioneering studies into seabird breeding biology on the island. In the 1980s, several CWS biologists undertook the enormously difficult task of determining the size of the seabird populations on Triangle Island. This research established a critical baseline of breeding seabird information.

In 1994, CWS launched a seabird research and monitoring program on Triangle Island that continues today. This research is coordinated through the Centre for Wildlife Ecology at Simon Fraser University in cooperation with the Canadian Wildlife Service. The main objective of the research program is to provide the information necessary to enable the CWS to achieve its long-term conservation objectives for marine birds. To facilitate this work, biologists established a small research station on the shore of Triangle Island. The research has focused on addressing the three main threats for breeding seabirds in the Scott Islands: the lack of formal protection for critical marine habitat, climate change, and seabird by-catch and oiling.

Lack of formal protection

The primary objective of the proposed Scott Islands Marine Wildlife (MWA) Area is to protect the key marine habitat, including foraging habitat, for the huge number of seabirds that inhabit the islands. First, researchers needed to determine the foraging ranges, and locations, of seabirds that breed on the Scott Islands. To answer these questions, researchers fitted Cassin's auklets with radio transmitters during the chick-rearing period between 1999 and 2001. By flying transects in fixed-wing aircraft, they were able to locate the radioed birds at sea. In 1999 and 2000, Cassin's auklets were detected 50-75 kilometres southwest of Triangle Island, foraging for copepods off the continental shelf break and over deep water. In 2001, they foraged a similar distance, and over deep water, but to the north and west of the island. In 2002, researchers used the same techniques to locate foraging areas of rhinoceros auklets breeding on Triangle Island. Rhinoceros auklets foraged up to 80 kilometres north of Triangle, in waters just over 100 metres deep. They were probably foraging for sandlance or Pacific saury. Thanks to this research and previous work done on pelagic seabird distributions, biologists were able to determine biologically relevant boundaries for the proposed MWA.

Climate Change

Climate change is a potentially major threat to the seabird populations. It can alter the abundance and distribution of the food supply. Researchers have found that varying ocean temperatures can dramatically affect marine ecosystems. On the BC coast, the 1990s was the warmest decade of the century. It reported some of the highest surface temperatures on record.

Rhinoceros auklet

Since 1994, when the research program on Triangle Island began, biologists have been attempting to assess the effects of ocean climate variability on seabirds. They began by monitoring the survival and breeding success of adult seabirds. They also examined and analyzed the variations in adult body condition, and variations in nestling diets and growth. They have determined seabird breeding success on Triangle Island by compiling estimates of successfully hatched eggs and fledged chicks. During 1994-2003, researchers found that the warmer weather dramatically affected seabird breeding success. It corresponded to poor reproductive success for Cassin's auklets, rhinoceros auklets, and tufted puffins. The birds were affected in all stages of breeding. In years when the ocean was warm, females were less likely to lay eggs. Those that did were less likely to hatch their eggs, fewer of the chicks survived to leave the nest, and the few chicks that did fledge were very light (which could impede their survival at sea).

The research showed that warmer weather reduced the abundance and availability of key seabird food sources. In particular, there were fewer copepods for Cassin's auklets, and fewer Pacific sandlance for common murres, tufted puffins, and rhinoceros auklets. In 1999, a cold ocean regime moved in. Cassin's auklet breeding success has improved since then. On Triangle Island, the numbers of adult and young Cassin's auklets has increased. More extensive study is required to determine whether these trends reflect normal population fluctuations, or whether the declines in the late 1990s were unique.

Gillnets

Seabird oiling and bycatch

Recent analyses indicate that oiling and by-catch are responsible for much of the mortality of common murres in BC waters. Scientists have become concerned about the population-level effects of this mortality on murres in the region. In neighbouring Washington State, common murres have been declining for a decade. High rates of by-catch may be contributing to this decline. Historically, over 95% of BC murres have bred in the vicinity of Triangle Island. In 2002, researchers began a demographic study of common murres at Triangle Island. The objective was to determine if the local population is declining, and whether oiling and by-catch are significant factors. Scientists monitored the annual variation in adult survival, breeding success, and chick diets and growth. In summer 2003, they resurveyed all common murre breeding sites around Triangle Island, and compared the results to those of a similar survey performed over a decade earlier.

The research found that numbers of common murres declined by between 24% and 30% over that time. Yet breeding conditions and success appear favourable for murres on Triangle Island. Biologists suspect that population declines may be driven by factors operating outside the breeding season and away from the island. They intend to continue monitoring common murres at Triangle Island, and hope to carry out a complete survey of all historical murre colonies in the area.

Currently, researchers in BC are also developing spatio-temporal "risk of oiling" models based on seabird distributions and shipping information (courtesy of G. McGowan of the Marine Communications and Traffic Services of Vancouver), as well as trajectory models to predict where seabird carcasses would go if they were oiled in BC waters. These models should help scientists improve their understanding of the possible impacts of oiling on local seabird populations. As well, the models can be used as a tool to interpret beach bird surveys that are used throughout the world to monitor seabird mortality associated with chronic ship-source oil pollution.