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How Much Habitat Management is Needed to Meet Mallard Production Objectives?

Tables

Table 1. Nest success estimates (%) used in mallard model simulations on Plots 601 and 701, representing North Dakota landscapes, 1987.
Habitat Plot 601 Plot 701
Barrena
0.0 0.0
Fenced habitatb
54.1 54.1
Croplandc
5.2 5.2
CRPd
20.0 20.0
Grasslanda
10.9 6.1
Grassland on WPAa
36.6 20.9
Haylandc
13.3 13.4
Odd areaa
9.7 5.4
Planted covera
17.1 9.7
Wetlande
18.2 18.2
Right-of-waye
6.7 6.7
Scrub and woodlanda
5.3 2.8
a Derived by the methods of and data used by Klett et al. (1988) with addition of new data for the period 1985-1989.
b From Cowardin et al. (1988).
c The model used step functions for time within these habitats. Tabulated estimates are model results based on these functions and were not adjusted for regional differences.
d Estimate based on Kantrud (1993) and unpublished data (R.E. Reynolds, U.S. Fish and Wildl. Serv., Bismarck, N.D.).
e Based on unpublished data (on file Northern Prarie Wildl. Research Cent.).

 

Table 2. Comparison of total recruits produced from a breeding population of 1,000 mallard pairs by stochastic and deterministic models from a 2-habitat plot containing CRP cover and grassland in North Dakota.
Managed (%) Total Recruits
Stochastica (SE) Deterministicb
0 842 (15.7) 876
10 1,220 (12.5) 1,271
20 1,258 (20.6) 1,323
30 1,282 (25.1) 1,344
40 1,276 (11.6) 1,355
50 1,280 (25.0) 1,362
60 1,291 (13.6) 1,367
70 1,300 (10.2) 1,370
80 1,318 (21.1) 1,373
90 1,246 (22.1) 1,375
100 1,306 (19.5) 1,376
a Standard error is for 8 executions of the model.
b Recruits from the deterministic model are higher because "alpha" = 1 in the deterministic model (Cowardin and Johnson 1979).

 

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