BAYER: SEABIRDS NEAR OREGON ESTUARINE SALMON HATCHERY 



Table 3.— Percentage of daily maximum number of birds observed within 2 h of ac- 

 tual high tides, early low tides (i.e., time of low tide before 1500 PDT), and late low 

 tides (i.e., time of low tide after 1800 PDT). Censuses between 6 July and 17 September 

 1982 at regions A-D with 9-11 censuses/d (i.e., 13-14 h period). N = total censuses; 

 CV = coefficient of variation. 



'Heterogeneity, Kruskal-Wallis H c = 16.36, P< 0.01. 



heterogeneity, Kruskal-Wallis H c = 7.62, P< 0.10. 



heterogeneity, Kruskal-Wallis H c = 0.80, P > 0.10. 



"Heterogeneity, Kruskal-Wallis H c = 5.62, P > 0.10. 



5 Heterogeneity, Kruskal-Wallis H c = 1.87, P > 0.10. 



tern of more birds present the first day after a 

 release than later; this pattern, however, was sig- 

 nificant only in 1983 (Tables 4, 5). In contrast, only 

 "active" cormorants were more numerous the 

 second day after a release than on the first day; 

 however, the differences in cormorant numbers 

 among days were only significant in 1983 (Table 

 5). 



Numbers of pigeon guillemots and Caspian terns 

 did not show any indication of dependence on the 

 number of days postrelease. The differences in 

 pigeon guillemot numbers in the 1 June-30 August 

 period among 1,2, and 3-6 d postrelease was insig- 

 nificant (1982: F = 0.23, df = 2, 34; P > 0.10; 1983: 

 Kruskal-Wallis H c = 0.61, P > 0.10). Sample sizes 

 were too small to test differences for Caspian terns 

 in 1982, but in 1983 variation with 1, 2, and 3-6 d 

 postrelease was insignificant in either the 1 June- 14 

 July period (when there were few Caspian terns 

 (Kruskal-Wallis H c = 2.74, P > 0.10)) or the 15 

 July-30 August period (when they were abundant 

 (Kruskal-Wallis H c = 2.74, P > 0.10)). 



4000 



cr 



3 2000 



- 800 



o 



c 



400 1 



J I I 



T , T ,  T 



- 



13 14 15 16 17 18 19 20 21 22 

 JULY 1983 



Figure 3.— Number of brown pelicans, "active" cormorants, 

 "active" gulls, and common murres with relation to dates of salmon 

 smolt releases during 14-22 July 1983 censuses that were within 

 2 h of low tides before 1500 PDT. 



Table 4.— Numbers of common murres at regions A-C in 1982 and 1983 during the 1 June-31 July period when 

 murres were abundant and the 1-30 August period when murres were infrequent in 1983. N = number of cen- 

 suses (1 census/d within 2 h of low tides before 1500 PDT); MAX = maximum number of birds counted. 



1 Heterogeneity among days: Kruskal-Wallis H = 4.88, P > 0.10. 



21982 vs. 1983: Mann-Whitney U = 52, P > 0.10. 



3 1982 vs. 1983: student's f = 2.12, df = 12, P< 0.10. 



"1982 vs. 1983: not tested because of small sample sizes in 1982. 



M982 vs. 1983: Mann-Whitney U = 38, P < 0.02. 



6 Heterogeneity among days: Kruskal-Wallis H = 8.91, P < 0.05. 



283 



