Summary of reproductive parameters in 3 Acorn Woodpecker populations.

  Hastings Reservation, California Water Canyon, New Mexico Research Ranch, Arizona
Clutch size
Single female groups only 4.37
All groups 4.98
Percent of groups not attempting a nest 18.9 26.2 37.1
Percent of groups with second nests 9.8 8.8 0.0
Fall nests
Percent of groups 4.8 0.0 0.0
Percent of years 34.4 0.0 0.0
Annual reproductive success (all nests)
Young/group/year 2.53 1.67 1.06
Young/bird/year 0.61 0.58 0.49
Young/breeding attempt 2.42
Annual reproductive success (successful nests only)
Young/group/year 3.63
Young/bird/year 0.87
Young/breeding attempt 3.17
Percent of groups that successfully rear
1 brood 60.1
2 broods 10.1  
3 broods 0.1
≥ 1 brood 70.3 60.1 48.5
Sample size (no. of group years) 1784 164 33