Nesting habitat and diet studies of sandhill cranes (Grus canadensis) from the central and north coast of British Columbia

• Main Author: Roessingh, Krista
• Other Authors: Smith, Daniel J., Jelinski, Dennis E.
• Format: Thesis
• Language: English
• Published: 2012
• Subjects: envir; geo; Crowberry; Empetrum nigrum
• Online Access: http://hdl.handle.net/1828/4168

Graduate The purpose of this study was to document the occurrence, habitat, and diet of sandhill cranes that breed in coastal British Columbia, a population believed to belong to the subspecies rowani. Specific objectives were to: 1) locate cranes and their nests in selected coastal areas of the central and north coasts (5138’N, 12805’W - 5400’N, 13037’W) and foster observer expertise in conducting aerial crane surveys; 2) describe sandhill crane nest habitat using a range of stand- and site-level characteristics; and, 3) identify diet content of breeding cranes from faecal samples. Helicopter surveys were conducted within 1.5 km of the coastline during May 2007 and 2008. Twenty nest sites were visited in 2008 to collect data on nest habitat characteristics. Satellite imagery was used to measure stand-level and landscape features for 29 nests. Faecal samples were collected at 6 nest and roost sites. During the 2008 survey, 104 cranes and 19 nests were counted over a 430 km2 area (average survey effort = 2.0 km2/min.). Crane nests were located in bog habitat, while cranes frequented bogs, shorelines, and marshes. Nests were in bog pools under 0.5 ha in size with the exception of one that occured in a 1.2 ha beaver-dammed pond (median = 0.10 ha, inter-quartile range (IQR) = 0.037 – 0.17 ha, n = 29), and had median water depth of 56 cm around nest islets (IQR = 49 – 77 cm, n = 21). Bog pools were in forest or woodland bog openings with median distance from the pool edge to the nearest treeline of 46 m (IQR – 24 – 160 m, n = 25) and median forest buffer width of 150 m (IQR = 93 – 260 m, n = 25). Forested habitat may serve as a corridor for cranes with pre-fledged young connecting bog nest and roost sites with shoreline foraging areas. Median distance from nest to shoreline was 400 m (IQR = 200 – 500 m, n = 28). Food items characteristic of faecal samples (n = 138) included mussel (Mytilus edulis), periwinkle (Littorina littorea) and limpet shells, insects, sedge (Carex spp.) and crowberry (Empetrum nigrum), ...