Portal de Periódicos da CAPES

Correction of Data Reported on Atlapetes brunnei-nucha

1954; Oxford University Press; Volume: 56; Issue: 4 Linguagem: Inglês

10.2307/1365117

1938-5129

Kenneth C. Parkes,

Avian ecology and behavior

the bird came earlier until I realized that it now came before my own supper hour instead of after it., Only at mid-winter did I become aware of a behavioral pattern and begin a record of its movements.With the aid of an electric torch it was discovered that the bird did not fly over the house but went to roost up under the wide eaves on a cross beam and that it was a female Sparrow Hawk (F&o sparverius) on its postbreeding grounds.From then on, as nearly as my own schedule would permit, daily observations were made;noting the time of the bird' s arrival and checking it against the daily published record of the sun' s movement.From January 6 to February 20, 1933, twenty-six arrivals were noted (see table 1).The average number of minutes between arrival and sunset was 12.7.The minimum was 4 and the maximum was 21.On the one overcast day it was 19 minutes and on the one rainy day, the hawk sat out on a light-pole for 12 minutes in a steady rain until time to go to bed under the protecting eaves.I learned that the bird had a regular air-way of approach.From the southeast it flew across a depression and up to a light-pole northeast of the house-always the same pole and always the same path through the air.There it would sit motionless until it flew directly to its roosting place.This practically unvaried pattern made my timing record much easier and more accurate.On two mornings the times of departure were recorded.They were 17 and 15 minutes before sunrise-only a little greater than the average evening period of lag.Here was an individual with a remarkably regular schedule that seemingly was unaffected by overcast skies and which rarely varied notably from the average to produce the two extremes of the record.The cause of these variations is still an unsolved question.Was the regular delay period on overcast or even rainy days the result of a habit induced originally by sensitivity to light?What caused the very short periods of only 4 and 6 minutes?These were on closely approximated days in the record.Was there perhaps a physiological factor at work?On February 21 the hawk departed and was not seen again.