We were back in Gwaii Haanas June 27- July 1 for a second round of oystercatcher surveys. We were again fortunate to have very favourable weather (with the exception of one rainy morning!) which allowed the survey to proceed very smoothly. We again made the Bischof Islands our base and spent the following days revisiting shorelines in the surrounding area. Eggs had hatched at many of the territories that we had visited previously, adding the challenge of searching for well camouflaged chicks amongst the rocks. The task of locating the chicks was made easier if prey remains were present. Limpet, mussel and chiton shells get left behind as parents feed their young, and are a good clue to use when looking for chicks. Prey remains were collected during the survey and categorized back in camp in order to look at chicks diets...Limpets are still the most popular item by far, followed by mussels, chitons and small abalone. We in fact observed an oystercatcher pry loose an abalone only to have it snatched by an opportunistic gull that was sitting nearby...keeping the chicks fed might not always be as easy as it looks!
Ancient Murrelet funnels have been taken down and packed up for the season. They are installed each year just before chicks beg in hatching and taken down soon after the breeding season finishes...removal this season was delayed somewhat by our Black Oystercatcher survey in Gwaii Haanas.
Most cavity nesting birds have fledged from the wildlife trees. There have been several new discoveries in the past week: Two Chest- nut-backed Chickadee nests and two Red-breasted Sap sucker nests. These new discoveries bring the season’s nest total up to 11 sapsuckers, 4 Brown Creepers, 3 Chestnut-backed Chickadees, and 1 Hairy Woodpecker...a productive year for cavity nesting birds! We are particularly surprised at the abundance of Brown Creepers this season. Creeper nests have only been found in nine years since 1990, and 1998 (2 nests located) was the only other year where more than one nest was found.
The last pair of murrelet chicks came down the funnels on the night of June 2. Over the course of the season, a total of 164 chicks were caught at North Cove (funnels 1-4), and 121 at Cabin Cove (funnels 5-8), for an overall total of 285. There have been no chick captures in North Cove for the past 3 years, yet chick numbers have continued to decline in this part of the colony. On a brighter note, there was a rebound in chick numbers at Cabin Cove this season: The total for funnels 5&6 was 86, an increase from the 66 captured in 2009 when a raccoon was active on the island through the breeding season. Preliminary analysis of this year's data is encouraging in that it appears that our research activities are not implicated in the declining numbers in the colony, however predation in the colony by introduced raccoons remains a major threat. A cull of raccoons on the adjacent shoreline of Louise Island in March apparently kept raccoons off of Limestone Island this season, and continuing this program on a yearly basis will be essential in reversing the decline of this colony.
The Ancient Murrelet chicks are still coming down the funnels with a total of 241 chicks as of May 27th. The peak occurred the night of May 21st with 15 chicks in North Cove and 18 in Cabin Cove. A great Southeaster blew in the following night and the numbers dropped substantially – only one chick in Cabin Cove on the 23rd and 24th. Since the storm passed more chicks have been departing nightly under much more favourable conditions. Many Fork-tailed Storm Petrels have been heard cackling late into the night and have be seen flying at the edge of the forest. Cassin’s auklets have also been heard calling near Lookout Point and along the coast north of camp. The breeding population of both these species has been steadily increasing on the island over the past few years.