Status and attempted reintroduction of burrowing owls in Minnesota, U.S.A.

Burrowing Owls (Athene cunicularia) have been recorded nesting in most of Minnesota's western counties. Considered common in the early 1920s, by the mid-1960s only 9-10 breeding pairs were known with estimates of no more than 20 pairs in the west-central part of the state. Ten breeding records exist for the period 1965-85. In 1984, Burrowing Owls were listed as Endangered by the State of Minnesota. In 1986, we began surveys and site management for nesting Burrowing Owls and experimented with a reintroduction program. From 1986-90, 13 nests were found at eight sites, with a mean reproductive success of 3.5 fledglings/pair. The maximum number of breeding pairs/yr was four. Nest burrows were found in alfalfa fields (37.5%), pastures (37.5%), roadside ditches (12.5%), and fencelines between row crop fields (12.5%). We released 105 wild, preflghted juveniles: nine in 1986, 18 in 1987, 21 in 1988, 27 in 1989, and 30 in 1990. Young owls were kept in hack pens with roofs and sides made from cotton mesh fish netting. Burrows inside each pen and in surrounding fields were available to the owls. Crippled adults were placed in each pen with the juveniles but were not released. We documented eight mortalities, all of which were fledglings recovered in the release area. No owls were found, or reported, after leaving their hack sites. No successful nestings occurred from 1992-98.