Archive for the ‘General’ Category

Winter Solstice Song Project 2009

Sunday, December 27th, 2009

Over the past two months I’ve been conducting my own version of Donald Kroodsma’s Solstice experiment. I’m not making any claims for the scientific rigor of this very informal experiment, but the results are interesting, and they do conform roughly to Kroodsma’s results.

Winter Solstice Song Project 2009
The X-axis represents the date and the Y-axis represents the number of song-type vocalizations heard.

    Methods

In early Nov. 2009 I established a route of 1.13 miles through Estabrook Park, Milwaukee, WI. This route takes an hour to walk at a relaxed pace. I attempted to start each session as close to dawn as possible and to complete the route in as close as 1 hour as possible. While walking the route I noted all song type vocalizations heard. Each bird making a song type vocalization counted as 1. I did not count additional songs coming from the same individual.

    Results

Nov 7, 2009: 0630-0730. Estabrook Park, WI., 52 degrees, clear skies.
0 song type vocalizations

Nov 14, 2009: 0640-0740. Estabrook Park, WI,. 44 degrees, cloudy.
0 song type vocalizations

Nov 21, 2009: 0650-0750. Estabrook Park, WI,. 45 degrees, cloudy.
1 singing House Finch

Nov 27, 2009: 0710-0810. Estabrook Park, WI,. 45 degrees, cloudy.
0 song type vocalizations

Dec 6, 2009: 0700-0800. Estabrook Park, WI,. 30 degrees, cloudy.
0 song type vocalizations

Dec 13, 2009: 0715-0815. Estabrook Park, WI,. 33 degrees, cloudy.
2 song type vocalizations: house finch, european starling

Dec 20, 2009: 0715-0815. Estabrook Park, WI,. 22 degrees, cloudy.
10 song type vocalizations:
1 house finch
1 robin
1 crow rattle
4 BCCH (2 countersinging)
3 WBNU (2 countersinging)

Dec 21, 2009: 0715-0815. Estabrook Park, WI,. 22 degrees, cloudy.
9 song type vocalizations:
4 BBCH
1 WBNU
2 House Finch
1 Robin
1 DEJU

Dec 24, 2009: 720-820, Estabrook Park, WI,. 32 degrees, cloudy and windy.
2 Song type vocalizations: 1 WBNU, 1 EUST

Dec 26, 2009: 720-820, Estabrook Park, WI,. 26 degrees, light snow, windy.
5 song type vocalizations:
3 BCCH (2 countersinging)
1 WBNU
1 crow rattle

Dec 27, 2009: 720-820, Estabrook Park, WI,. 22 degrees, cloudy.
7 song type vocalizations:
4 BCCH (2 countersinging)
1 WBNU
1 American Robin
1 EUST

    Discussion

I remain skeptical about the significance of the actual winter solstice to birds and its effect on their singing behavior. However, I do think that this experiment demonstrates that the beginning of the singing season falls at approximately the same time as the winter solstice for several common bird species of the eastern North American temperate forests. The species in question are the White-breasted Nuthatch and the Black-capped Chickadee. For the 6 sessions between Nov 7 and Dec 13, no White-breasted Nuthatches or Black-capped Chickadees were heard singing (they were seen or heard calling in all of these sessions, but not singing). After that date, the White-breasted Nuthatch was heard singing on all 5 sessions and the Black-capped Chickadee on 4 of the 5. This change in the singing behavior of these two species accounts for a considerable amount of the increased singing activity evident in the results.