WSP01978

• File Number: 8460.500
• Description: Platte River Recovery Plan
• Basin: South Platte
• Date: 9/1/1990
• Author: USFWS
• Title: Interior Population of the Least Tern - Recovery Plan
• Water Supply Pro - Doc Type: Publication

tern nesting areas should be developed.
213. Examine historic aerial DhotoEraDhv and hydrograDhic surveys
of river -systems to determine the Drevious extent of
Dotential habitat and ve~etational chanEes.
For many rivers periodic aerial photographs and hydrographic
surveys are available. It would be useful for predictive
purposes to measure the change, if any, in the quantity and
quality of sandbar habitat since photo and hydrographic
coverage began (Hamel et al. in press, Rodekohr and
Engelbrecht 1988, Sidle et al. 1989). Such an endeavor
would allow an accurate forecast of habitat trends.
22. Determine current miEration habitat reQuirements and status.
Because migration patterns of interior least terns are not
I understood, no information on habitat requirements or status is
available. Once stop-over sites, if they exist, are determined,
evaluation of habitat requirements should be undertaken.
221. Assess the characteristics. includinE Drev resources. of
miEration habitat.
If stopcover sites are identified, the habitats used should
be described and .variables characterizing those habitats
quantified. Quantification (time activity budgets) of how
interior least terns use the available habitats and their
length of stay at stop-over sites also should be determined.
222. Ouantifv and evaluate available miEration habitat.
Once migratory habitats are identified and characterized,
the availability of such habitats should be determined.
Initially, habitat availability in the vicinity of known
stop-over sites should be quantified and its quality
assessed. If migratory habitat in the vicinity of current
stop-over sites is limited, a large scale survey of
available habitat along suspected migratory corridors should
be made.
23. Determine current habitat reQuirements and status onwinterinE areas.
No data are available on interior least tern winter habitat
requirements. This task should be undertaken followed by a
determination of the extent to which wintering habitats are
traditionally used. Information on the role of winter habitat
abundance, distribution, and quality in interior least tern population
dynamics is totally lacking. Data relating winter habitat conditions
to population status are needed.
231. Assess the characteristics. includinE "rev resources. of
winter habitat.
As primary wintering areas are identified, characteristics
of the habitats used by interior least terns 'must be
quantified and variables affecting quality of those habitats
elucidated. Winter habitats should be assessed with regard
to interior least tern prey abundance and distribution,
roost site needs, and location of feeding and roosting
habitat. Habitat characteristics near occupied sites, but
not currently used by interior least terns, also should be
assessed. Quantitative data on interior least tern use of
winter habitats also are needed. Information on movements

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