Effects of Time of Day and Season on Winter Bird Counts

Abstract

We examined the effects of time of day and season on counts of wintering birds in a central Pennsylvania forest. Black-capped Chickadees (Parus atricapillus), Tufted Titmice (Parus bicolor), and White-breasted Nuthatches (Sitta carolinensis) were detected more often in the morning (07:00-10:59) than at other times, whereas White-throated Sparrows (Zonotrichia albicollis) were noted more often at midday (11:00-13:59). Numbers of contacts of all species combined were relatively similar between morning and midday but were much lower in the afternoon (_ 14:00). Black-capped Chickadees, Tufted Titmice, White-breasted Nuthatches, Golde -crowned Kinglets (Regulus satrapa), and White-throated Sparrows were observed more often in early winter (before 19 January) than later in the season. We conclude that winter bird counts can be conducted in both morning and midday hours with little or no qualitative loss of data. In addition, counts should be made in early winter to minimize the effects of food shortages later in winter that may influence avian mortality and movements to feeders.