Page "Lesser Scaup" Paragraph 28

The causes for this stark – though not threatening, as of yet – decline remain unknown.

There are indications that the breeding success is decreasing, but why this is so remains puzzling.

On one hand, pollution and habitat destruction, especially in the wintering regions, has certainly increased since the early-mid 20th century.

On the other hand, the narrow time frame in which Lesser Scaup breed and raise their young may be tied to some specific ecological conditions – such as abundance of key food items – which shifted winterwards due to global warming, without the ducks being able to adapt.

In this regard, it is alternatively or additionally possible that Great Scaup, which may be increasing in numbers, is putting the Lesser Scaup under increasingly severe competition.

There is also growing anecdotal evidence that the decision in the early 1980's to shift rearing operations of sport fish ( walleye and muskellunge ) from traditional man-made structures to existing shallow water basins in midwestern states ( Minnesota especially ) decimated the invertebrate populations formerly used by migrating hens for forage.

The migrating hens are thought to be arriving on the breeding grounds in such poor health that they are unable to nest or produce weak clutches.