Bird Deterrent Solutions for Crop Protection

Bird Deterrent Solutions for Crop Protection: Comparison

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

Visual deterrents present a visual stimulus to the birds that can trigger fear or curiosity. The dangerous feeling can be triggered by a real or simulated predator. In the case of real predators, this can lead to birds’ deaths. By contrast, there can be the use of something birds are not familiar with, such as scarecrows, dyes, lights, reflecting tape, optical gel, kites, balloons, or others. Some of these visual repellents can incorporate audio deterrents as well. A summary of the studies that have considered visual deterrents is provided in Table 1.

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.

	Author			Year		Area				Bird Species			Area		Deterrent Technique			Deterrent Technique		Success Rate				Success Rate		Negative Aspects			Conclusions
	Negative Aspects			Conclusions

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.

	Author			Year			Bird Species			Area			Deterrent Technique			Success Rate			Negative Aspects			Conclusions
^[4]	[6]		1990			Phalacrocoracidae			Aquaculture			Scarecrows/Sirens			Effective			N/A			The more realistic the facial and body shape, the more effective scarecrows are likely to be.		They can be more detectable if they are painted in bright colors.
^[
^[44]^[45]^[46]^[47]	[47,48,49,50]
^[75]^[76]		1939, 1968, 1986, 1989			[77,78]	N/A		⁹¹^]^[92]	[93	1988, 1990		,	N/A		94	Residential area		,	Chemical		95]	N/A			N/A
^[		Birds tend to not get used to it.
^90]^[
^[95]	[
^[		1978, 1981, 1981		98]	^118]	[121]	N/A			N/A			Exclusion				1976		N/A			N/A			N/A

	Anseriformes^[77]^[78]^[79]	[79,80,81]		1976, 1984, 1988			N/A		^[		Cities, agriculture, and airports		^93]	[96]		1936
^[100]	[103]1968			1968		N/A		Fisheries operations				Agelaius		N/A		Shotguns and Rifles				Corn fields		Tall Grass			Traps		Ineffective			N/A			Ineffective		Sometimes the birds die.			Long grass can attract rodents and birds of prey.			Agriculture		N/A		Prevents some birds from accessing food.		Due to the number of birds in the group, it is impossible to catch them all.
	Lure Area			N/A			N/A		N/A			Attracting and holding birds so that they will not go elsewhere.		^5]^[6]	[7,8]
^[17]	[18	^[101]		1995, 1997		]^[102	N/A
^[119]^]^[103		1989		N/A			Scarecrows/		Lights/Sound			N/A		^]	[104,105,^[106]	¹²⁰^]^[121		Chemical
^[96]	[99^]^[122]		[122,123,124,125]	1974, 1987, 1990		Aequornithes		N/A			N/A		]		1996				1975, 1974, 1978, 1981		N/A			N/A
	N/A		N/A		N/A		Agricultural fields			Shotguns and Rifles			Birds tend to not get used to it.
	Aquaculture ponds			Overhead Wires and Lines			N/A		Airport		Effective			N/A		“Poor grass”		N/A			Recommended as a method of deterring waterbirds from fishponds.
		N/A		Traps		Ineffective			Effective		Sometimes the birds die.					Magnetic Field, Microwaves		N/A			N/A		N/A			N/A		Bird numbers on poor grass were as low or lower than on long grass.				N/A		N/A			N/A		^[7]^[8]^[9]^[10]^[11]^[12]	[9,10,11,
^[14]^[4812,^]13,14]			[15,34]	1976, 1979, 1983, 1985, 1980, 1982			^[80]		1983, 1988		N/A			[	N/A		N/A			Airports		Scarecrows			Ineffective			Birds get used to it easily.			Short time application, needs to be used with other techniques.
82]	^[52]	[54]
^[97]		1997
	N/A					1981		Sturnidae			Laboratory		N/A		[100]		1996		Fish-rearing facilities		^[90]	[93]	Shotguns and Rifles
^[123		1978		N/A		Ineffective				Butorides virescens		^]	[126]	N/A		Sometimes the birds die.		Tactile repellents			Overhead Wires and Lines		May be effective					1997		Fish farm		Mowing at nighttime		N/A		Sturnus vulgaris			Traps		N/A		N/A			It may be possible to develop non-lethal, plant-based dermal repellent.
		Not Tested			N/A			N/A		Effective		N/A			Transportation costs		N/A		^[13
		Mowing late in the day or overnight can reduce the attractiveness of this activities.		The birds were released 40 km from the point where they were trapped, and never came back.
		Magnetic Field				Ineffective			N/A			Only been proven to disorient birds and not to disperse them.		^][22]^[14]^[15]	[5,
^[15,^49][16]		⁵⁰^]	[51,		[23]	^[94]	[97]	^[7]^[104]^[105]	[9,	1990, 1983, 1987		52	1998		N/A		]		N/A				1988, 1991			N/A			N/A				1990
^[98]	[101]107,108		Aequornithes		Tactile repellents				1997		Phalacrocoracidae, Ardeidae	]	N/A			1976, 1970, 1986		Fish farms		Scarecrows			N/A		Shotguns and Rifles		Larinae
^[124]^[125]			Airport		Airport			Live Ammunition		Ineffective			Birds get used to it easily.			Relocate every 2–3 days.
	Ineffective				Ineffective		Sometimes the birds die.			Birds habituate easily.			It was seen that in the short term it was effective
[127,128]		1971, 1973			N/A			N/A		Overhead Wires and Lines		May be effective				Effective		N/A		Killing some birds only had temporary effects.				N/A		Plant compounds that have been tested caused agitation and hyperactivity in the birds.		^[16]
	Microwaves			N/A				The effectiveness of overhead wires or lines varies widely among species and circumstances.			[
	Mowing at nighttime			Effective			N/A		N/A17]
		Mowing late in the day or overnight can reduce the attractiveness of this activities.			N/A		^[22]	[23]	^[22]	[23]		^[22]		1998		[23]	^[106]^[107]^[108
^[126]^]^[		1997			¹⁰⁹^]	[109,110,111,		[129 112]	1998		1998	]	Streptopelia orientalis		1968, 1970, 1976, 1991		N/AN/A		Flight Cage				Airport		N/A			N/A			Behavioral Repellents			N/A			Fruit trees
^[99]		N/A			N/A		Scarecrows		Can cause disorientation and erratic behavior.			N/A
[102]			1988			Laridae			Landfill		Effective			Pyrotechnics		Overhead Wires and Lines		N/A			Better than stuffed crows or kites.
		Effective				Changing water/feeding zones		Effective		Birds get used to it easily.				Surfactants				1985			N/A			N/A			Microwaves		Effective		N/A		High costs and difficult application in large areas.Only used in an initial approach.				It solves the problem of the presence of birds in a permanent way.		^[17
	N/A			By removing the water/food, the area is no longer attractive to birds.				N/A			N/A
	N/A			N/A			N/A		^]	[18]
^[24]	[25]	^[14]	^[22]^[81]^[82]		1989		[15,83,84]		[1976	Turdus merula, Anas platyrhynchos, Anser anser			4–6 acres sunflower fields			Scarecrows/		Propane cannon		23	N/A		Effective			1983, 1983, 1990		N/A		]	N/A			Ducks and geese spook more easily than blackbirds.
	N/A		Flares			May be effective			Fire hazard			In conjunction with other techniques, it can help to disperse the birds in a certain direction.			^[18]	[19]
^[51]^[52]^[53]	[53,54,55]	1974				1980, 1981, 1986		Charadriiformes			Fishponds			N/A		Scarecrows			Ineffective			Landfill sites			Pistols		N/A			Effective			N/A		Birds get used to it after two hours.
	Small area and short-term usage.		^[19]	[20]		1986			N/A
^[110]		1998		N/A			Behavioral Repellents		[	N/A		Effective			If the dose is too high, it can lead to the bird’s death.			Unaffected birds from the flock eventually escape due to the warning signal from the flock mate.
	Sanitary landfill		113		Foam			May be effective		]	Its effectiveness would be reduced in rainy or windy weather.			It could be used to cover small areas that are particularly attractive to birds.			^[14]^[81]^[82]^[83]^[84]^[85]	[15,83,84,85,86,87]		1983, 1983, 1990, 1970, 1973, 1970			Sturnidae, Turdus merula, Passeriformes, Laridae, Corvus Corax			Air bases		^[54]	[56]	Various crops				1991			Branta canadensis			Urban parks		Reflective Tape			Screamer shells		Effective	Very Effective	May interfere with walking on the terrain.	Tape 0.025 mm thick and 11 mm wide. High winds may increase efficiency.
N/A			Long-term effects, the concentration of geese in the area was reduced by 88%.		^[20]	[21]
^[24]	[25]	1986			1976		Turdus merula			N/A		Crops			Reflective Tape			Effective				N/A		May interfere with walking on the terrain.		Mortars		If the tape gets twisted, it can be less effective.			Tape 3 m apart from each other at 0.5 to 1 m from the ground.
May be effective			Highly skilled operator. Safety hazard; there have been several accidents related to the use of mortars.			If they produce a loud bang, they are more effective at daytime and in a larger area than other pyrotechnic devices.		^[21]	[22]
^[55]^[56]	[57	1990		,	Anser anser		58	20.2 hectares of winter wheat		]	Reflective Tape				1974, 1990		Effective
^[22
^[127]^[128]	[130,131]	1997			1965, 1969		Turdus merula, Sturnidae			N/A			Surfactants			Effective			Laridae, Melopsittacus undulatus, Gallus gallus domesticus, Columbidae		38.2 million blackbirds and starlings were killed between 1974–1992.		Laboratory			PA-14 did solve local roost problems.
	Microwaves			N/A			The radiation levels are considerably higher than the levels that are safe for humans.			N/A		^]	[23]	Behavioral Repellents			^[104]		Effective			N/A			[107]	1998		N/A		N/A			Lakes, ponds…			Bird Balls			May be effective				1976N/A
		Laridae
^[74]^[129]^[130]^[131]^[132]^[		Airbase		¹³³		Falconry, Pyrotechnics			Effective		^]	[76,132,133,134,135,136]		1996, 1946, 1949, 1954, 1971, 1972			N/A			N/A			Microwaves		It was necessary to replace two falcons each year.		Are very easy to install and require significantly less maintenance.				N/A		Four goshawks were successfully used at an airbase in Holland to clear the runways from gulls.
	N/A			Few studies have reported that radars have caused behavioral changes in flying birds.		^[22]	[23]	^[111]	[114]	1998			Branta Canadensis, Laridae, Sturnidae			Laboratory, sanitary landfill, airports
^[134]		ReJeX-iT			Effective		^[		N/A			ReJeX-iT can be effective at deterring birds in certain situations, but the doses used in some studies were not effective.
¹³⁵^]	[137,1970	138	Laridae			Airbase			Falconry			Effective		]	N/A		1972, 1965			Sturnidae, Anas platyrhynchos, Laridae			Laboratory		Gulls showed no signs of habituating to the goshawks during the two-year study.
		Laser			N/A			Could cause hemorrhage in birds’ eyes.			Not recommended		^[86]	[89]	^[112]	[115	1992		]
^[136]	[139]	1996		Anas platyrhynchos, Branta Canadensis			Laboratory			Dimethyl and Methyl anthranilate			Very Effective			N/A			1980		Laridae			Laridae		Military Airfield		When subjected only treated grain, both ducks and geese reduced their food intake.
	Falconry				Landfill		N/A			N/A			Laser		Not recommend as a routine method for bird control at civil airfields.		Ineffective
	N/A			Not recommended		^[87]May interfere with walking on the terrain if the tape gets twisted; it can be less effective.			[	20 mm thick red fluorescent tape. The lines were tied at 40 to 60 m between rows of wheat.
90		N/A		]	N/A				^[113] 1995		[116]	Gas cannon				1978		Larus delawarensis, Larus argentatos, Anas platyrhynchos				Laridae		Pools of water in fieldsN/A				Airfields		Methyl anthranilate		N/A			Effective		The noise of the explosion resembles or is louder than that of a 12-gauge shotgun.					Falconry, Pyrotechnics, Model Gulls		N/A			N/A
	N/A			N/A			N/A		^[22]	[23]		1998			Gas cannon and others
^[52]^[53]	[54,55]	^[88]	[91]
^[26]^[27]		1981, 1986		N/A		^[²⁸^]	[27,28,29]	1996		N/A		Vineyards				Branta Canadensis				1985, 1986, 1987		N/A		Branta Canadensis		Areas up to 4 ha		Hawk Kites and Balloons			Ineffective				Airfields		Gas cannon		Methyl anthranilate		Birds get used to it easily.			Short-term utilization.
		Effective			Falconry		Ineffective		N/A		N/A				Ineffective			Proven to be effective deterrents for areas up to 4 ha in the cases of nongame species.		Product concentration used in		N/A		^[87][90] did not repelled this species.		^[23]	[24]		1983
^[57]^[58]^[59]	[59,60,61]		N/A			Agricultural			Dead Bird Models				1984, 1990, 1990		N/A
	N/A			Laridae		^[89]	[92]	Landfill
^[114]		1993			N/A			Ponds at airports		[	ReJeX-iT		Effective		N/A			Effective		N/A		N/A
	N/A			Gas cannons, in combination with other dispersal methods such as pyrotechnics, have been found to reduce numbers of gulls.			Bird numbers decreased in treated ponds.		^[14]^[24]^[25]	[15,25,26]
^[14]^[24]	[15,25]	1983, 1976, 1980			1983, 1976		N/A			N/A		Airports			Various Crops		Dead Bird Models				Av-alarm		N/A				Effective		N/A			N/A		N/A
		AV-alarms appear to have been used successfully to reduce numbers of small birds.		^[26]^[27]^[28]^[29]	[27,28,29,
^[60]30]			[62]	1985, 1986, 1987, 1990				1985		Larus delawarensis			Sturnus vulgaris, Passer melanurus, Ploceus velatus		City			Grape culture		Dead Bird Models/Pyrotechnics/Falconry			Av-alarm		Effective				Effective		N/A				N/A		The use of this method is recommended, but the positive results are partly due to the use of pyrotechnic material.
	Can be effective in reducing the damage to grapes.		^[22]	[23]		1984			N/A			Agriculture			Aircraft			N/A			Dangerous to the tripulants.			Not		recommended
^[61]	[63]		1970			Sturnidae			Blueberry crops			Av-alarm and others			Effective			N/A			It worked better in conjunction with shotguns or propane cannons.		^[14]^[30]^[31]	[15,31,33

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.

117

]

1983

Columba palumbus

Brassica fields

Falconry

Ineffective

N/A

After repeated attacks by the goshawk, the pigeons usually resettled and continued to feed.

^[115]

[118]

1978

Laridae

Landfill

Falconry

Very effective

Some birds died

The effectiveness seemed to derive from the cumulative effects of several bird control episodes.

^[22]^[116]^[117]

[23,119,120]

1998, 1965, 1980

]

^[62]

[64]

1983, 1967, 1990

1978

N/A

Telluraves

Farms/Airports

Cornfields

RC Aircraft

Av-alarm and gas cannon

N/A

Effective

N/A

Better results were obtained by combining both methods.

^[32]^[33]

[32,35]

^[63]

[65

1975, 1981

]

Sturnidae, Charadriinae, Anser anser, Anas platyrhynchos

Airport, City

RC Aircraft

1983

Very effective

N/A

Requires a highly skilled operator.

Birds may habituate slowly to a model aircraft that actively hazes them, especially if it has a falcon shape.

Av-alarm

Ineffective

N/A

AV-alarm was not as effective as distress calls in repelling birds.

^[34]

[37]

^[64]^[65]

[66

1987

Sturnidae

Roost

]

Lights/Predator Model

1990, 1990

N/A

Effective

Av-alarm

N/A

Ineffective

N/A

Birds accustomate to this sound.

^[24]

[25]

^[66]

[68]

1976

1979

Anas platyrhynchos

Grain Fields

Sturnidae

Searchlights

Effective

N/A

Av-alarm

May attract birds if it is nighttime or if the weather is cloudy or foggy.

Ineffective

N/A

It is recommended in certain weather conditions.

Starlings only increased slightly the heart rate when they were exposed to AV-alarm.

^[35]

[38]

1975

^[67

Vanellinae, Larinae

Airport

Lights

⁶⁸

Effective

N/A

^[36]

[39]

1982

N/A

Airport

Lights

Ineffective

N/A

Whether the plane had its lights on or not, the results were the same.

Limited effectiveness

Ineffective to gulls (Larinae), blackbirds (Turdus merula), and starlings (Sturnidae).

50–60% success rate.

^[11]

[13]

1980

Anseriformes

Oil Spill

Lights

Ineffective

N/A

3. Auditory Deterrents

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.

Table 2.

Summary of the studies using auditory deterrents.

	Author			Year


Laridae


N/A


Falconry

	N/A			Falcons cannot fly with bad weather.			Dealing with gulls with bad weather is a problem.
^]


[
69
,70]		1973, No date			Aequornithes			Aquatic terrain			Av-alarm			May be effective		N/A			Insufficient details to assess changes in bird numbers.
^[69]^[70]	[71,72]		1973, 1968			Laridae			Airport			Predator Sounds			Effective		N/A			The playback of a Peregrine Falcon call was effective at dispersing gulls.
^[37]	[40]		1986			Corvus Corax, Pica, Cyanocitta cristata
^[71]	[73]		1957			Anas platyrhynchos		Airport				Ponds		Lights			High-intensity Sounds		Ineffective			Effective		N/A			Can cause hearing damage and other human health effects.		Birds were more frightened by the plane than by the lights.
	Some birds vacate the pond after two or three days.		^[38]	[41]		1992
^[72]	[74]		Falco sparverius, Leucophaeus atricilla				1986			Laridae		N/A			N/A	Lights				Ultrasounds		May be effective				Ineffective		N/A			N/A		Lights that flash faster increase the birds’ heart rate more in the short term, but lights that flash more slowly manage to keep the average heart rate higher.
		Found no evidence that gulls either heard or reacted to ultrasounds.		^[39]	[42]		1976
^[73]	[75]			1992		N/A			N/A		N/A			Lights		N/A			N/A			Ultrasounds			Ineffective		N/A			Frequencies should not exceed 100 Hz.
	N/A			Bird population did not decrease in more than 5%.		^[40]^[41]	[43,44]
^[74]	[76]	1976, 1976				1996		Larinae, Sturnidae, Columba livia				N/A		N/A		N/A		Lights			Effective			No repellant effect was observed when the strobe light flashed at higher frequencies to 60 Hz.			Gulls delayed approaching a feeding point by 30 to 45 min.
	Infrasounds			Ineffective			N/A			Birds do not associate these sounds with danger.		^[42]	[45]		1993		Falco sparverius, Leucophaeus atricilla			Laboratory			Lights			Ineffective			N/A			Birds did become attentive to the lights, but it did not necessarily mean that it frightened them away.
^[14]^[43]	[15,46]		1983, 1977			Anseriformes, Charadriiformes, Passer, Larinae, Turdus merula, Sturnidae			Oil Spill			Lights

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.