Red-breasted Merganser - Kouchibouguac

Red-breasted mergansers (Mergus serrator) are colonial birds found on Tern Islands, a set of three small barrier islands separated by water at high tide located within Kouchibouguac National Park. These piscivorous sea ducks are indicators for the state of the breeding islands and associated marine or estuarine ecosystems, since nest distribution and productivity is closely related to habitat conditions such as the presence of marram grass (Ammophila breviligulata) in addition to sometimes sea lyme grass (Leymus mollis) or common yarrow (Achillea millefolium); while the occurrence of the species is also linked to the scope and abundance of fish resources. The purpose of the red-breasted merganser monitoring program is to determine the annual number of nesting attempts and to measure nest success, as these are important parameters that contribute to breeding population dynamics. The methods for this measure involve an annual census in mid-August where nests (i.e., a bowl with at least one egg) are located by systematically searching the vegetated regions on Tern Islands immediately following the completion of the breeding season. Nests are marked with an unpainted wooden stake placed 1 m north of the nest and location coordinates are obtained with a global positioning system. The number of successful, abandoned, or predated nests is recorded along with clutch size and nest stage assessed from egg temperatures.