Inventory 



Inventory should be conducted on streams where harlequin ducks have been observed but breeding 

 status is unknown and on streams which are potentially suitable harlequin duck habitat (see conservation 

 assessment), including those listed in Appendices B and D, Table 3. On streams where breeding status is 

 unknown, a minimum of 4 surveys, 3 of which are pair surveys, should be conducted over a period of 3 

 or more years prior to determining stream status. On streams which are potential habitat, but where no 

 ducks have been observed, at least 4 surveys should be conducted over 2 years, including at least 2 pair 

 surveys, prior to determing stream status. However, if a brood or nest is observed at any time during 

 surveys, the stream will be classified as a breeding stream. 



Survey Methodology 



Timing is critical for both inventory and monitoring surveys. Timing is probably the most 

 important factor in survey success. For this reason, most surveys must be conducted specifically for 

 harlequin ducks, rather than in combination with fish or other wildlife surveys. Survey are conducted 

 during two periods: spring pair surveys and summer brood surveys. 



Pair surveys 



In the northern Columbia Basin and Rocky Mountain Front subprovinces, spring pair surveys 

 should be conducted between 25 April and 25 May. In the Intermountain subprovince spring pair surveys 

 should be conducted between 5 May and 15 June. Although these are the periods when pairs are most 

 likely to be observed, even when conducted during this period, surveys underestimate the actual number 

 of pairs present by an average of 31 percent (Cassirer and Groves 1994). Because count accuracy can be 

 variable, at 2 surveys should be conducted during this period for monitoring purposes. The survey with 

 the highest number of ducks should be used for monitoring estimates. 



Brood surveys 



Brood surveys conducted for monitoring purposes should occur between 15 July and 5 August in 

 the northern Columbia Basin subprovince and between 1 August and 21 August in the Intermountain 

 subprovince. Although ducklings hatch several weeks prior to these dates in both subprovinces, because 

 of mortality rates typically occurring in young ducklings, surveys conducted during this period give a more 

 accurate estimate of ducklings fledged. Ducklings should be aged by plumage development (Fig. 1) during 

 brood surveys. Inventory surveys for presence only can be conducted as early as 1 July in the northern 

 Columbia Basin and as early as 15 July in the Intermountain subprovince. 



Inventory surveys should cover the entire stream from 2nd- or 3rd-order headwaters to the mouth. 

 Inventory of this area should be conducted during the spring, and again during the summer, (or until ducks 

 are observed, whichever is first) for at least 2 years before determining stream status. Therefore, inventory 

 should be an ongoing program, not simply associated with proposed management activities. 



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