Update on the Status and Breeding Phenology of the Timberline Sparrow (Spizella breweri taverneri) in Alaska

In July 2020 we located 10 singing Timberline Sparrows [Spizella (breweri) taverneri] in the region of Gold Hill, Nutzotin Mountains, east-central Alaska. All birds were on southeast-facing slopes in the ecotone between subalpine scrub and alpine tundra, to which habitat breeding Timberline Sparrows seem narrowly confined. The population’s estimated density of 0.77 birds/km2 was similar to that at the time of its discovery in 1994. We located the first active nest of the Timberline Sparrow reported for Alaska, ~0.3 m above the ground in a shrubby resin birch (Betula glandulosa). An observation of young fledged on 11 or 12 July 2020 implies egg laying in the third week of June, later than the beginning of the breeding season of Spizella (breweri) breweri.

Snow Meltout Dates and Breeding Density in Brewer's Sparrows (Spizella Breweri)

We have conducted a breeding bird monitoring program in GTNP since the early 1990s, utilizing fixed-area census sites of around 5 ha in size. The sites are located throughout the park in all habitat types and elevations, and number 30 in all. Some have been censused each year in June, at the height of the breeding season, others have been censused repeatedly but more sporadically, and others less frequently. the power of these census data to interpret variation in bird species, composition and breeding densities, species to species, site to site and especially year to year, clearly increases with the longevity of the data set. With the data from some sites now covering 18 successive years (1991-2008), it is possible to attempt some interpretation of the bird species variables. One such is reported here. The influence of snow meltout date on breeding density of a common species of the sagebrush flats, Brewer's Sparrow Spizella breweri.