Theoretical concepts from foraging ecology were studied to identify elements of blackbird foraging strategies that may be manipulated to deter blackbirds feeding on rice. Seed-handling time was identified as one such vulnerable element. Consequently, we developed seed coatings for rice that increased handling time per seed, allowed a satisfactory germination rate, and persisted for several days postplanting. Test coats included hydrophilic binders with several starches, clays, plaster of paris and chemical grout in various combinations. Consistent repellency was achieved in feeding trials with captive red-winged blackbirds.

Bird damage to early-ripening Florida blueberries was estimated to be approximately 17% in 1988 (2 sites) and ranged from 17% to 75% in 1989 (3 sites) when a late winter freeze severely reduced expected yield. Monetary loss due to bird damage in 1989 may have exceeded $4500/ac at one site. In Florida, birds appear to have a significant impact on the early-season fresh market blueberry industry. The problem is likely to worsen as the planting of high-value, early-ripening varieties spreads to other parts of the state and ripening times overlap with wintering frugivorous birds.

In east Texas, bird damage to sprouting rice was reduced in two of seven study plots when rice seed was treated with the fungicide Kocide® SD at the maximum label rate (8 fluid oz/100 lb seed). Foraging rates of male redwinged blackbirds (Agelaius phoeniceus) in treated plots were lower P = 0.02) than were those in control plots. We suspect that the copper in Kocide SD produces physiological effects that suppress feeding activity that results in reduced losses in some cases. Because it is registered for use on rice and is relatively inexpensive, Kocide SD may be a useful component of some bird damage reduction strategies.

At 3 sites in Chambers County, Texas, the estimated sprout loss in 1-ac plots sown with clay-coated rice seed averaged 17.0% compared to 36.5% in adjacent 1-ac control plots. In one field, bird use of the control plot was 14 times that of the treated plot. Average feeding rates of red-winged blackbirds (Agelaius phoeniceus) were 1.5 seeds/min and 8.4 seeds/min in the treated and control plots, respectively. Roadside counts of territorial male redwings and evening flightline counts of birds going to roost indicated a depredating population consisting mainly of nonbreeding, roosting birds early in April with increasing proportions of breeding birds as the rice-planting season progressed. The results of this study are consistent with previous laboratory findings and with predictions from foraging theory. Further development and field testing of the seed coating will be required before the technique becomes generally available as a method for reducing bird damage to sprouted rice.

The effectiveness of eyespot balloons in discouraging boat-tailed grackle (Quiscalus major) use of a simulated orange grove was investigated in a series of 4-day trials. The mean distance to the trees of 6-bird experimental flocks was the same with a plain white balloon present as with no balloon. A white balloon with red and black eyespots kept birds at a greater distance from the trees throughout the trial. The presence of a black balloon with orange and yellow eyespots did not repel the birds from the grove. Observations of birds using the area within 1 m of the trees revealed no effect due to the eyespot balloons nor was the number of oranges pecked reduced in the presence of the eyespot balloons. These results were primarily due to a single bird that consistently ignored the white eyespot balloon during the 4-day trial, entered the grove, and avidly pecked the fruit. In combination with other crop protection devices, eyespot balloons may prove effective in deterring bird use of citrus trees.