Colony Development and Density-Dependent Processes in Breeding Grey Herons
Table 1
Mean values of the breeding duration, nestling feeding duration, number of fledglings per successful nest, and date starting breeding in each nest. The proportion of successful nests to fledge and the date of the first breeding in the colony are also shown.
Number of nests used
Breeding duration
Nestling feeding
Successful
Number of fledglings/
Date of the
Date of the beginning
Colony
Year
(days)
duration (days)
nests
successful nest
first breeding
of each nest breedingb
Mean
SD
N
Mean
SD
N
Percentage
N
Mean
SD
N
in the colonyb
Mean
SD
CV (%)
N
Renkoji
1996
10
Renkoji
1997
37
102.5
6.9
19
67.3
17.1
15
85.3
34
3.1
0.7
29
48
78.1
26.4
33.8
34
Renkoji
1998
43
106.7
14.7
24
58.6
16.3
24
92.1
38
2.5
0.9
35
62
74.9
18.1
24.1
33
Renkoji
1999
60
106.6
16.0
20
64.6
17.0
20
64.4
45
2.2
0.7
29
62
79.6
16.5
20.8
58
Renkoji
2000a
49
0
0
0.0
49
0
47
0
Tama Zoo
2000
14
Tama Zoo
2001
26
114.6
15.0
15
65.9
16.8
7
85.0
20
1.9
0.7
17
45
83.8
18.0
21.5
25
Tama Zoo
2002
122
99.1
16.2
56
57.3
12.1
43
70.7
92
2.1
0.9
65
49
75.5
22.1
29.3
78
Tama Zoo
2003
111
113.4
15.5
82
64.6
11.0
76
82.5
103
2.5
0.8
85
42
75.9
26.0
34.3
106
Tama Zoo
2004
136
111.1
19.2
79
60.6
17.6
77
79.5
122
2.4
0.9
97
26
72.1
29.2
40.6
135
Tama Zoo
2005
175
120.9
22.1
112
60.4
13.4
95
81.5
157
2.1
0.8
128
4
64.3
35.8
55.6
156
Tama Zoo
2006
201
123.8
21.1
102
61.7
14.5
89
62.6
182
2.0
0.8
114
12
68.6
27.4
39.9
195
Tama Zoo
2007
218
126.6
21.3
125
63.4
17.4
106
79.9
174
2.1
0.8
139
35
69.4
29.2
42.0
208
Tama Zoo
2008
178
114.3
16.9
102
59.3
11.6
96
75.8
149
2.0
0.8
113
27
67.4
21.2
31.4
166
Tama Zoo
2009
180
129.0
21.1
105
67.8
16.7
85
79.1
153
1.8
0.6
121
23
57.0
24.4
42.8
183
Tama Zoo
2010
171
125.9
21.3
117
53.6
17.4
113
77.7
157
1.9
0.6
122
31
67.9
20.9
30.8
155
Tama Zoo
2011
167
125.2
24.7
93
63.3
18.5
99
79.3
150
2.0
0.8
119
38
73.6
31.2
42.4
130
aAll nests were abandoned in this year; bdate is presented by days since the 1st of January in each year.
