You're using an outdated browser. Please upgrade to a modern browser for the best experience.
Please note this is a comparison between Version 1 by Pedro D. Gaspar and Version 2 by Peter Tang.
Weeds, pathogens, and animal pests are among the pests that pose a threat to the productivity of crops meant for human consumption. Bird-caused crop losses pose a serious and costly challenge for farmers.
- birds
- deterrents
- agriculture
- crops
1. Introduction
Pests, especially weeds, pathogens, and animal pests, pose a threat to the productivity of human-consumable crops. Bird-caused losses to fruit crops pose significant and expensive problems for farmers. Estimates on potential and actual losses caused by different bird species were discussed in a study carried out in Sweden between 2000 and 2015 [1]. During those years, there were 2194 complaints of crop damage, corresponding to a total loss of approximately 34,500 tons of various crops. The bird species that caused the most damage were, in order of the percentage of total losses from highest to lowest, the common crane (Grus grus) (33.7%), the barnacle goose (Branta leucopsis) (33.5%), the greylag goose (Anser anser) (26.6%), the bean goose (Anser fabalis fabalis) (2.6%), and the whooper swan (Cygnus cygnus) (2.2%). The remaining 1.4% of the total losses were caused by other birds.
Another study [2] aimed at finding out which bird species were directly related to crop damage. Visual damage was collected on 60 randomly selected plants: 12 at each cardinal point and 12 inland in New York State. It was focused on four different crops from 81 field locations: sweet cherry—23; blueberry—12; apple—24; and vine—22. Damages were estimated at 2.3% for apple fields, 3.6% for grapes, 22% for blueberries, and 26.8% for sweet cherries. In addition, surveys were also conducted on farmers with those crops via the Internet, mail, and telephone in New York, Michigan, Washington, Oregon, and California. New York farmers alone pointed out that, all together, they lose about $6.6 million per year and that 65.6% of them are taking measures to scare the birds away. Half of the farmers confirmed that birds are the biggest factor in crop loss.
A study conducted in Poland [3] concluded that, in the years 1974 and 1980, 22% and 16%, respectively, of cherry crops were destroyed by sturnids (Sturnidae). The same study also conducted another survey in four districts of Poland aimed at all crops. In Gdansk, 471 surveys were filled out, of which 27% stated with certainty that their fields were damaged by rooks (Corvus frugilegus), and 59% had suspicions that the damage that appeared on their crops was also caused by rooks. In Warsaw, 51% of 378 questionnaire respondents were certain that they had damage caused by rooks. In Kielee, 56% of 351 questionnaire respondents reported damage, and, in Wroclaw, 58% of 276 questionnaire respondents also confirmed damage caused by rooks. In that same survey, overall bird damage was also collected for four crops: wheat, oats, corn, and barley. In the four districts, corn losses ranged from 22% to 32%, wheat losses from 10% to 13%, barley losses from 3 to 18%, and oat losses from 8 to 15%.
2. Visual Deterrents
Table 1.
Summary of the studies using visual deterrents.
Author | Year | Bird Species | Bird Species | Area | Deterrent Technique | Success Rate | Negative Aspects | Conclusions |
|---|
5. Exclusion Deterrents
These are devices or materials used to serve as a physical barrier. If access to a certain area, for example, where there is food or shelter, is restricted, the birds will leave the area and move on. There are also apparent barriers (i.e., there is no actual barrier).
Physical barriers are normally made up of wire mesh, polyethylene, or other synthetic materials and serve to prevent birds from approaching a specific area. They also serve to prevent them from nesting in these areas. The metal mesh can also be interconnected with electrified wires so that when birds land there they receive a harmless shock [90][91][92][93,94,95].
A summary of the studies that have considered exclusion deterrents is provided in Table 4.
Table 4.
Summary of the studies using exclusion deterrents.
Author | Year | Bird Species | Area | Deterrent Technique | Success Rate | Negative | Aspects | Negative Aspects | Conclusions | |||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Conclusions |
.
Table 5.
Summary of the studies using habitat modification methods.
Table 6.
Summary of the studies using removal deterrents.
Author | Year | Bird Species | Area | Deterrent Technique | Success Rate | Negative Aspects | Conclusions |
|---|
Table 7.
Summary of the studies using other deterrent techniques.
6. Habitat Modification
Habitat modification is the removal or alteration of the natural characteristics of a site. It may include trees and shrubs, the removal of ponds, planting in areas without flora, planting crops that are not attractive to birds, such as tall grass, eliminating possible nesting areas, the use of exclusion methods barriers, and even chemical agents used in the birds’ natural foods.
A summary of the studies that have considered habitat modification methods is provided in Table 5
7. Removal Deterrents
This method consists of catching birds and releasing them away or eliminating them, either with traps, poison, or the use of lethal ammunition. It is a method that requires skills to be used, because it may use materials that can be lethal to humans as well. Using lethal methods would only work in the short term and only reduce the bird’s local population.
A summary of the studies that have considered removal deterrents is provided in Table 6.
These are methods that use auditory techniques to deter birds. Most auditory deterrents also have a visual component.
A summary of the studies that have considered auditory deterrents is provided in Table 2.
3. Auditory Deterrents
Table 2.
Summary of the studies using auditory deterrents.
4. Chemical Deterrents
Chemical aversion techniques have been used in a variety of contexts, from residential areas [75][76][77,78] and cities, to agriculture and airports [77][78][79][79,80,81]. Birds do not tend to get used to these types of techniques.
A summary of the studies that have considered chemical deterrents is provided in Table 3.
Table 3.
Summary of the studies using chemical deterrents.
Author | Year | Bird Species | Area | Deterrent Technique | Success Rate |
|---|
8. Other Deterrent Techniques
A summary of the studies that have considered other deterrent techniques is provided in Table 7.