WSP03031

• File Number: 8543
• Description: Closed Basin Division
• State: CO
• Basin: Rio Grande
• Water Division: 3
• Date: 6/1/1981
• Title: Fish and Wildlife Plan - Closed Basin Division - San Luis Valley Project
• Water Supply Pro - Doc Type: Report/Study

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The National Wetland Inventory (filS 1979) revealed 43,122 acres of wetlands in
the Closed Basin project area. As shown in table 1, the project area produces
approximately 13,620 ducks annually at a density of .31 ducks/wetland acre.

A resident population of Canada geese breed in the San Luis Valley. Approximately
100 of those utilize the Closed Basin project area for nesting and produce 160
young (80 percent success, 4 yg./brood).

B. Other Water Bird Use

Other water bird data is very limited for the project area. The Bureau of
Reclamation conducted aerial surveys within the area to determine the general
seasonal use by wetland type. However, the collected data is not sufficient
to extrapolate production estimates. Use-day information for Alamosa and
Monte Vista NWR may be more appropriate in determining other water bird use of
the project area.

In general, the species have been classed into three types: raptors,
shorebirds, and marsh and water birds. Use by these species in the San Luis
Valley varies with each individual species. Some of the species such as
American avocets, Wilson's phalarope, killdeer, common snipe, rails, black-
crowned night herons, snowy egret, marsh hawk, Swainson's hawk, and short-eared
and great horned owls breed in the valley. The majority of the other species
are either fall and spring migrants or winter visitors. Most' of the breeding
species either leave during winter months or remain in reduced numbers.

The quality and quantity of the wetlands in the San Luis Valley probably have
the greatest effect on the breeding species that breed there. Wetland vigor and
abundance will determine how many of the species can find nesting places and how
many young they can produce. For mtgratory species and winter visitors, wetland
health plays an important role, but not as critical as for the breeding species.
Numbers of migrants are affected by the availability of suitable breeding
habitat, storms during migration periods, winter weather, and the available
winter habitat.

The following lists in tables 2, 3, and 4 ate by no means a complete species
list for wetlands in the San Luis Valley in 1979 and 1980. They are the most
conspicuous species and hence the most frequently seen. In addition to these
species, numerous songbirds also use wetlands and wetland edges.

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