Avian Use of Rice Baited Trays Attached to Cages with Live Decoy Blackbirds in Central North Dakota
Abstract
The viability of a management program using DRC-1339 (3-chloro-4-methylanaline
hydrochloride) rice bait and live decoy blackbirds to reduce avian depredation on
sunflower was assessed. In fall 2007 and 2008, observations were conducted at
bait trays attached to decoy traps in central North Dakota. Study participants
randomly visited the bait sites for 1-h intervals throughout daylight hours to record
numbers, species, and ages (when possible) of blackbirds (targets) and nonblackbirds (non-targets) on the bait trays and nearby baited gravel roadsides.
Researchers observed the bait trays for 1011 hand recorded 3,888 birds,
representing 25 species, 12 families, and 3 unidentified birds. The red-winged
blackbird (Agelaius phoeniceus) (n=3,006) was the most common target species,
whereas clay-colored sparrows (Spizel/a pa/Iida) (n=12) and savannah sparrows
(Passercu/us sandwichensis) (n=12) were the most numerous non-target species
observed on trays. The sparrow family (Emberizidae) was the most prevalent of
non-target observations, with 50 individuals representing 8 species and 21
unidentified individual sparrows. Overall risk to non-target species appears
minimal, and use by blackbird species was minimal in comparison to the local
population. Baited roadsides were used infrequently by blackbirds. Based on this
research, use of DRC-1339 rice-baited trays with accompanying live decoys and
rice-baited roadsides are not cost-effective methods of reducing blackbird damage
to sunflower.