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Table 1 Statistical output (F-values with P-values in parentheses) from general linear mixed models, with individual as a random effect, describing six foraging parameters for thick-billed murres and black-legged kittiwakes as a function of year, time of day (circularly-transformed) and windspeed

From: Windscapes shape seabird instantaneous energy costs but adult behavior buffers impact on offspring

Parameter N Year Crosswind Tailwind Time
Murres
Outbound wing beat frequency 10 2.63 (0.11) 0.221 (0.66) 13.5 1 (0.0004) 0.05 (0.89)
Flight speed 35 23.2 (<0.0001) 3.58 (0.06) 171.1 (<0.0001) 0.08 (0.78)
Energy delivery rate between 0600 h and 1000 h EST 82 2.61 (0.11) 6.48 (0.01) 2  
Time flying per day 210 2.96 (0.02) 0.06 (0.81)2  
Residual of daily energy expenditure on body mass 49 1.53 (0.22) 2.21 (0.14)2  
Residual of chick growth rate on age3 720 4.23 (0.04) 0.39 (0.93)2  
Kittiwakes
Wing beat frequency 10   0.11 (0.87) 4.67 (0.04) 0.25 (0.61)
Flight speed 10   1.58 (0.22) 178.9 (<0.0001) 0.01 (0.98)
Feeding rate between 900 h and 1300 h AKDT 96   4.41 (0.04) 2  
Time flying per day 30   0.45 (0.51)2  
Residual of daily energy expenditure on body mass 37   0.01 (0.92)2  
Residual of chick growth rate on age3 126 0.49 (0.46) 3.94 (0.05)2  
  1. 1Actual direction of flight was unknown, so we assumed 101 ± 10° for outbound direction (average from birds equipped with GPS).
  2. 2Average wind speed, rather than crosswind and tailwind components, used as independent variable. To account for the confounding effect of date on wind, average windspeed for each day was calculated as residual from the average value for a given date across all 10 years.
  3. 3Hatch date (murre: F1,2876 = 10.9 P = 0.001; kittiwake: F1,686 = 2.25, P = 0.13) was also included as a covariate.
  4. Values in bold are statistically significant at the P < 0.05 level and values in italics are significant at P < 0.002.