Numbers and movements of yellow rails along the St. Lawrence River, Quebec

Abstract

From 1993-1996, we surveyed, banded, and radio-tracked Yellow Rails (Coturnicops noveboracensis) along the St. Lawrence River, in southern Quebec. We conducted night surveys at Ile aux Grues (IAG), and banded 130 individuals at several localities. We recaptured individuals 82 times, 7 of which were returns (same site, different years), 5 were displacements (same year, different sites), and 1 was a recovery (different site and year). Up to 20 calling males were surveyed at IAG during a given night, and each year the number of rails heard calling increased from mid-June until the first days of August, and then decreased through late August until calling was no longer heard. We argue the increase in rails heard on IAG in July and early August occurred because birds moved to the island, whereas the decrease in rails heard in late August occurred because birds stopped calling and began molting; indeed, all displacements were from rails recaptured at IAG and three rails were recaptured at IAG during their complete prebasic molt. Some Yellow Rails may move from other areas along the St. Lawrence River to IAG in order to molt, probably because IAG harbors the largest high-marshes along the river and is free from terrestrial predators. Although they may not be indicative of a genuine molt migration, our results are suggestive of a molt migration similar in some ways to that known to occur in waterfowl and coots.