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Variability in Nest Survival Rates and Implications to Nesting Studies

Tables


Table 1.  Basic nest information and hatch rates.
 

 

1976 1977
Mallard Blue-winged
Teal
Mallard Blue-winged
Teal
Number of nests 
      Destroyed 89 118 28 28
      Hatched 41  95 55 78
Exposure days 1,966 3,460 1,651 2,140
Hatch rates 
      Traditional Method    31.5    44.6    66.3    73.6
      Mayfield Method    20.7    30.7    55.9    63.9
      Product Method    17.3    29.5    43.2    51.1
      Intercept Method    7.7    20.0    13.5    22.2

 

Table 2.  A relationship of hatch rates and average nest age to sampling intensity from 1976 Mallard data.
Search
interval
in weeks
Number
of nests
found
Average age
at discovery
(days)
Hatch rates
Traditional Mayfield
1 130    8.9 31.5 20.7
2 97 11.6 37.8 23.6
3 80 13.8 41.6 24.2
4 68 15.5 45.8 25.4

 

Table 3.  Exposure, losses, and estimated daily mortality rate (m) for 1976 Blue-winged Teal nests according to age of nest and calendar period.
Calendar
period
Age of nest (days) Total
1-5 6-10 11-15 16-20 21-25 26-30 ≥31
        120-129
Exposure 17 13 2 0 0 0 0 32
Losses 0 0 0 0 0 0 0 0
m 0 0 0 0
        130-139
Exposure 41.314 96.736 107.929 27.202 2.328 0 0 275.509
Losses 1.883 2.569 5.381 2.436 0.115 0 0 12.384
m 0.0456 0.0266 0.0499 0.0896 0.0494 0.0449
        140-149
Exposure 40.888 191.551 282.710 212.401 84.222 15.104 2.000 828.876
Losses 2.201 7.198 9.444 6.046 3.295 0.104 0 28.288
m 0.0538 0.0376 0.0334 0.0285 0.0391 0.0069 0 0.0341
        150-159
Exposure 11.848 63.653 208.746 307.019 279.517 171.235 43.540 1,085.558
Losses 0.348 1.878 9.072 8.243 6.445 4.077 2.730 32.793
m 0.0294 0.0295 0.0435 0.0268 0.0231 0.0238 0.0627 0.0302
        160-169
Exposure 9.856 37.899 77.037 112.356 185.893 263.282 184.725 871.048
Losses 1.269 2.530 2.608 5.185 5.783 6.128 4.410 27.913
m 0.1288 0.0668 0.0339 0.0461 0.0311 0.0233 0.239 0.0320
        170-179
Exposure 0 12.054 33.727 33.844 57.980 81.498 77.090 296.193
Losses 0 1.663 1.320 1.610 1.729 2.922 1.924 11.168
m 0.1380 0.0391 0.0476 0.0298 0.359 0.0250 0.0377
        180-189
Exposure 0 2.443 1.908 14.599 23.413 35.009 32.575 109.950
Losses 0 0.538 0.462 0.385 1.125 1.750 1.185 5.445
m 0.2202 0.2421 0.0264 0.0481 0.0500 0.0364 0.0495
       Total
Exposure 120.906 417.336 714.057 707.421 633.353 566.128 339.933 3,499.134
Losses 5.701 16.376 28.287 23.905 18.492 14.981 10.249 117.991
m 0.0472 0.0392 0.0396 0.0338 0.0292 0.0265 0.0302 0.0337

 

Table 4.  Mean square error (MSE) resulting from fitting either models to each data set. A and D represent linear effects of age and date, respectively; A2 and D 2 the corresponding quadratic effects; A*D the interaction; and A1 and A2 linear effects of age for nests < and >11-15 days. Italicized terms indicate models that provided best fit to data on basis of MSE and significance of included terms.
  1976 1977
Model Blue-winged Teal Mallard Blue-winged Teal Mallard
A 0.01946 0.02100 0.00747 0.01054
A + A2 0.01982 0.02030 0.00641 0.00986
A1 + A2 0.01997 0.01961 0.00565 0.00975
A + D 0.01813 0.02067 0.00755 0.01034
A + D + A*D 0.01793 0.02100 0.00729 0.01044
A + A2 + D 0.01847 0.01987 0.00647 0.00965
A1 + A2 + D 0.01862 0.01909 0.00566 0.00958
A + A2 + D + D2 0.01871 0.02020 0.00659 0.00987

 

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