Two nests in thirty years: what a single Haida Gwaii murrelet find fixes

A nest is the unit of evidence this file has always been shortest of. Two confirmed on Haida Gwaii in total, the newest found this summer after a gap of more than 30 years ^[1], works out to about one confirmation per 15 years across the known record ^[1]. Everything else on the terrestrial side is inference. Crews pick candidate trees by looking for large moss-covered branches, open flight paths through the canopy and platforms the birds are known to prefer ^[8], which is a description of trees birds have already been found in, used to predict trees nobody has checked.

The reason inference had to carry that weight is arithmetic. Murrelets leave the ocean in spring and fly inland, sometimes more than 80 kilometres, to lay one egg on a mossy branch high in an old forest ^[5]. Draw a half-circle of that radius behind a single stretch of coast where birds were caught and you are looking at roughly 10,000 square kilometres of forest ^[2]. The commuting flights are timed for the dim light of dawn and dusk ^[6], and unlike almost every other seabird there is no colony on a cliff or rock to find instead ^[13].

GPS changes the denominator rather than the difficulty. Tags are taped to the back feathers of birds netted at night from an inflatable and drop off at the moult ^[9]; most of the positions they return are at sea, and the rare inland fix is what converts a region into a stand worth walking ^[10]. After that it is still legwork: viewing points marked by day, a hike back in the dark, an hour of waiting before first light for an adult to slip off the nest and head for the water ^[11].

The marine half of the design is why one tree matters beyond itself. Fecal and water samples, read against ocean measurements, identify what the birds eat and which marine habitat they use ^[3], and the same birds haul fish inland daily to a single chick ^[12]. Old-growth loss in British Columbia and changing ocean conditions are both named pressures on a species listed as threatened under the Species at Risk Act ^[7][4]. A bird tracked at both ends is where those two pressures can be weighed against each other instead of argued separately. That the research is run in partnership with the Council of the Haida Nation and Environment and Climate Change Canada ^[2] means the nest location arrives as something the Haida Nation helped produce, not a result mailed in afterwards.

One number is missing, and it is the one that would let anyone judge the method. The published account breaks off before saying how many tags went out this season ^[14], so nests found per bird tagged, the only figure that tells you whether this is repeatable or a good night, is not yet on the table.