Ecological Archives E092-065-A1

Walter D. Koenig, Leslie Ries, V. Beth K. Olsen, and Andrew M. Liebhold. 2011. Avian predators are less abundant during periodical cicada emergences, but why? Ecology 92:784–790.

Appendix A. Results of the analyses for individual species.

TABLE A1. Stop-level analysis comparing the number and proportion of sites within Brood X where birds declined between year –1 and year 0 divided between stops where cicadas were heard vs. those where they were not.

  Cicadas heard$ No cicadas heard$  
Species N surveys
declining
Total surveys
conducted
% surveys
declining
N surveys
declining
Total surveys
conducted
% surveys
declining
P #
Red-headed Woodpecker 4 4 100.0 3 4 75.0 1.00
Red-bellied Woodpecker 19 31 61.3 14 31 45.2 0.31
Blue Jay 19 33 57.6 22 33 66.7 0.61
American Crow 34 45 75.6 34 45 75.6 1.00
Tufted Titmouse 29 47 61.7 28 47 59.6 1.00
White-breasted Nuthatch 7 11 63.6 6 11 54.5 1.00
Brown-headed Cowbird 12 25 48.0 12 25 48.0 1.00
Common Grackle 17 35 48.6 20 35 57.1 0.63
Northern Cardinal 24 49 49.0 24 49 49.0 1.00
House Sparrow 14 22 63.6 11 221 50.0 0.54
Brown Thrasher 7 12 58.3 5 12 41.7 0.68
$ Includes only surveys where at least one individual was counted in year –1 at both stops where cicadas were heard and those where they were not; no such sites were available for American Kestrels.
# Comparisons by Fisher exact tests.

TABLE A2. Route-level analysis comparing the number and proportion of surveys where birds declined between year –1 and year 0 in surveys within the range of Brood X where cicadas were and were not heard calling.  

  Calling cicadas heard$ No calling cicadas heard$  
Species N surveys
declining
Total surveys
conducted
% surveys
declining
N surveys
declining
Total surveys
conducted
% surveys
declining
P #
American Kestrel 17 24 70.8 6 18 33.3 0.03
Red-headed Woodpecker 7 12 58.3 8 14 57.1 1.00
Red-bellied Woodpecker 17 33 51.5 10 22 45.5 0.78
Blue Jay 16 33 48.5 13 28 46.4 1.00
American Crow 22 33 66.7 16 28 57.1 0.60
Tufted Titmouse 16 33 48.5 17 28 60.7 0.44
White-breasted Nuthatch 15 27 55.6 7 20 35.0 0.24
Brown-headed Cowbird 14 33 42.4 14 28 50.0 0.61
Common Grackle 18 33 54.5 17 28 60.7 0.80
Northern Cardinal 20 33 60.6 14 28 50.0 0.45
House Sparrow 16 33 48.5 16 27 59.3 0.45
Brown Thrasher 12 31 38.7 12 24 50.0 0.43
$ Includes only surveys where at least one individual was counted in year -1.
# Comparisons by Fisher exact tests.

TABLE A3. Range-level analysis comparing the number and proportion of surveys where birds declined between year –1 and year 0 within the range of Brood X and those outside of but within 50 km of Brood X.

  Within range of Brood X$ Outside range of Brood X$  
Species N surveys
declining
Total surveys
conducted
% surveys
declining
N surveys
declining
Total surveys
conducted
% surveys
declining
P #
American Kestrel 36 53 67.9 20 37 54.1 0.19
Red-headed Woodpecker 18 32 56.2 18 28 64.3 0.60
Red-bellied Woodpecker 46 83 55.4 35 72 48.6 0.42
Blue Jay 46 92 50.0 45 96 46.9 0.77
American Crow 61 90 67.8 47 97 48.5 0.008
Tufted Titmouse 56 90 62.2 44 87 50.6 0.13
White-breasted Nuthatch 34 64 53.1 26 58 44.8 0.37
Brown-headed Cowbird 40 91 44.0 36 88 40.9 0.76
Common Grackle 49 92 53.3 48 96 50.0 0.67
Northern Cardinal 49 92 53.3 52 98 53.1 1.00
House Sparrow 55 90 61.1 47 88 53.4 0.36
Brown Thrasher 39 79 49.4 38 76 50.0 1.00
$ Includes only surveys where at least one individual was counted in year -1.
# Comparisons by Fisher exact tests.

TABLE A4. Season-level analyses comparing the number and proportion of BBS routes where birds declined between year –1 and year 0 vs. the number and proportion of CBC sites conducted during the prior winter where birds declined. (Note: the BBS data are identical to the “within range of Brood X” half of TABLE A3)

  BBS routes$ CBC sites$

 

Species N surveys
declining
Total surveys
conducted
% surveys
declining
N surveys
declining
Total surveys
conducted
% surveys
declining
P #
American Kestrel 36 53 67.9 35 71 49.3 0.04
Red-headed Woodpecker 18 32 56.2 24 42 57.1 1.00
Red-bellied Woodpecker 46 83 55.4 34 71 47.9 0.42
Blue Jay 46 92 50.0 30 71 42.3 0.35
American Crow 61 90 67.8 37 71 52.1 0.05
Tufted Titmouse 56 90 62.2 46 71 64.8 0.75
White-breasted Nuthatch 34 64 53.1 41 71 57.7 0.61
Brown-headed Cowbird 40 91 44.0 34 52 65.4 0.02
Common Grackle 49 92 53.3 35 50 70.0 0.07
Northern Cardinal 49 92 53.3 50 71 70.4 0.04
House Sparrow 55 90 61.1 42 71 59.2 0.87
Brown Thrasher 39 79 49.4 14 18 77.8 0.04
$ Includes only surveys where at least one individual was counted in year -1.
# Comparisons by Fisher exact tests.

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