The University of California, Davis, starling research program was broadened in 1976 to encompass agricultural pest birds in general. Under new direction there were a number of applied problems studied. The effects of feeding cattle only between 1600 hours and 0800 hours on cattle weight gain was studied with results indicating slower weight gains and lower meat quality when compared to cattle fed ad lib. Feed component selection by starlings (Sturnus vulgaris) was also studied finding that a starling selected diet contains a higher percentage of the high protein components than present in a commercially prepared dairy feed ration fed to them. References are given to papers on a damage assessment technique for grapes, a field test of methiocarb as an avian repellent to protect figs, and a field test using Avitrol treated seed to control house finches (Carpodacus mexicanus). An overview of continuing research activities and a status report on the bird damage specialist position is discussed.

A bait preference field study of the California ground squirrel (Spermophilus beecheyi beecheyi) was performed involving the comparison of the following untreated bait formulations fed ad lib: oat groats, Ramik Green, and ZP Rodent Ag Bait. The study was performed on rangeland at California Polytechnic State University, San Luis Obispo, California, from March 11, 1984, to September 15, 1984. Poor bait quality problems occurred in the early period of the study (March 11 to May 17), resulting in poor acceptance of both Ramik and Ag Bait. A descriptive analysis of this period is discussed. The statistical analysis of relative bait consumption (June 3 to September 15) determined a significant difference between the consumption of oat groats versus Ramik and Ag Bait; no significant difference between Ramik and Ag Bait; the acceptance of all three baits was good; and the use of any of the three would result in control of the ground squirrels. There was a strong correlation between overall bait consumption and the ground squirrels observed.

As the number of crops that are mechanically harvested increases, the reports of rodent problems associated with those crops increase also. This report examines the rodent problems in mechanically harvested tomatoes and reports on work done in studying the effects of various border crops on rodent populations. It also looks at possible rodent management options available to growers of mechanically harvested crops.

We examined the status of trapping to control bird damage based on a nation-wide questionnaire, literature, and on-site visits of trapping programs. We mailed 464 questionnaires to Agriculture Commissioners in California, Cooperative Extension Wildlife Specialists, USDA APHIS Wildlife Services personnel, state Department of Agriculture personnel, and members of the National Animal Damage Control Association. Two hundred fifty questionnaires (54%) were returned from 50 states, 1 territory, and 51 California counties. Fifty-four percent of the respondents indicated they either trap, monitor, or provide information on bird trapping. Regarding specific activities, 49% actively trapped while 43% provided information only. By affiliation, 90% of private respondents trapped, followed by 60% of federal respondents. Respondents listed 53 species of birds causing damage. Cited most often were rock doves (Columbo livia), European starlings (Sturnus vulgaris), blackbirds, Canada geese (Branta canadensis), American crows (Corvus brachyrhynchos), house finch (Carpodacus mexicanus), and house sparrows (Passer domesticus). Respondents listed 52 crops, 18 types of animal production facilities, and 16 non-crop sites that were subject to bird damage. Respondents listed 25 species that were trapped. Modified Australian crow traps, walk-in traps, and drive traps were used most frequently. Most respondents (80%) rated trapping as moderate to excellent for ducks, geese, rock doves, and house sparrows. Trapping for starlings was rated as moderate to excellent by 75% of private industry respondents (mostly non-agricultural damage), but 80% of California county returns (dealing mostly with agricultural damage) rated it as slight. Differences in control ratings for some species related to the type of damage site, geographic location, and organizational affiliation. Most (57%) respondents felt trapping was not important in overall bird control in any crop. California Agriculture Commissioners (>70%), however, indicated trapping was important for starling and house finch control, particularly in grapes. Most respondents (71%) felt trapping for bird control stayed at the same level or increased since 1990, and 82% thought it would stay the same or increase in the future. This sentiment was strongest among respondents from private industry (93% ). We identified literature on general trapping concepts, specific traps, trapping techniques, and operational trapping programs. We found no rigorous evaluations of trapping’s effectiveness or the factors influencing results. Three studies provided partial economic analyses, but most evaluations of trapping put emphasis on the numbers of birds caught rather than the amount of damage eliminated in relation to the cost of control. New trap designs or trapping strategies that may have application to current bird problems include the impact trap, the Modesto funnel trap, noose-covered wickets, glue-coated perches, decoy-crop trapping, trammel nets, and mist nets. We identified five California counties currently monitoring house finch trapping. From 1991 to 1995, an average of nearly 100,000 house finch have been trapped annually. Only Sonoma County currently traps with county personnel, taking an average of 1,000 starlings/year from 1991 to 1995. We conclude trapping for bird control: 1) is commonly used across the country by a broad segment of wildlife damage control practitioners; 2) is important for the control of selected species, such as starlings and house finch in California; 3) is important for bird control in certain crops such as grapes in California, and non-crop sites such as around buildings in urban areas; 4) will continue to be used at the same or increased levels in the future; 5) has not been rigorously evaluated from a cost-benefit standpoint; 6) can be improved with new trap designs and strategies; and 7) merits additional research.

Pistachio orchards were selected and evaluated for damage caused by either scrub jays (Aphelocoma coerulescens) or American crows (Corvus brachyrhynchos). The distribution of damage caused by each species was evaluated and quantified. The percentage of trees damaged by scrub jays ranged from 58% to 99% and tended to be distributed randomly throughout the orchard. In orchards with crow damage, the percentage of trees damaged ranged from 18% to 46% and damage tended to be aggregated. Data from orchards were used to evaluate the relative accuracy and precision of various sampling strategies. Randomly distributed bird damage could be sampled with relatively simple strategies such as walking diagonally across the orchard. Aggregated bird damage was most effectively sampled using stratified random sampling. If action thresholds are going to be used to determine when bird control programs should be initiated, an understanding of the distribution of bird damage in a crop must be understood so reasonable sampling techniques can be developed.

In 1984 studies were initiated to identify the bird species causing damage to pistachio nuts, quantify the losses, and explore possible methods for alleviating bird losses. The first year's field observations were made to identify and determine the level of activity of the various depredating bird species in the orchard. Field samples of nuts were collected to assess the levels of damage occurring in representative orchards. A mail survey of all commercial pistachio growers in California was conducted to determine which bird species growers believed were the cause of nut losses, the extent of damage they have experienced and what, if any, bird control methods they have used. The objective of the second year was to further evaluate production losses due to crows and scrub jays. During the damage season, evaluation of various types of baits for crows and scrub jays was made in several pistachio orchards. Finally, with most growers reporting the use of shooting to frighten and disperse the birds from the orchard, an initial effort to evaluate shooting as a control method was made.