Biomimetic Design for Pest Bird Control UAVs: A Survey

Abstract

This paper presents a survey of biomimetic design on small unmanned aerial vehicles (UAVs) for pest bird management in agriculture. The current pest bird control methods used in agriculture are introduced first, followed by a discussion of the advantages and limitations of these control methods. A discussion of why biomimetic design on UAVs is of high interest is then presented. A few of the typical biomimetic designs implemented on small UAVs are then compared, with an emphasis on the key design elements used, feasibility and effectiveness. The limitations of these biomimetic designs are analysed, and potential pathways to resolve these limitations are discussed. A conclusion is drawn at the end of this paper to summarise the current biomimetic designs.

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17th Australian Aerospace Congress, 26-28 February 2017, Melbourne
Biomimetic Design for Pest Bird Control UAVs: A Survey
Zihao Wang 1, Dr. Andrew Lucas 2, Dr. KC Wong 1 and Prof. Gregory Charmitoff 1
1 School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney
2 Agent Oriented Software Pty Ltd
Abstract
This paper presents a survey of biomimetic design on small unmanned aerial vehicles (UAVs)
for pest bird management in agriculture. The current pest bird control methods used in
agriculture are introduced first, followed by a discussion of the advantages and limitations of
these control methods. A discussion of why biomimetic design on UAVs is of high interest is
then presented. A few of the typical biomimetic designs implemented on small UAVs are then
compared, with an emphasis on the key design elements used, feasibility and effectiveness. The
limitations of these biomimetic designs are analysed, and potential pathways to resolve these
limitations are discussed. A conclusion is drawn at the end of this paper to summarise the current
biomimetic designs.
Keywords: unmanned aerial vehicle (UAV), pest bird damage control, biomimetic design,
autonomy
Introduction
Pest bird damage in agriculture is a significant problem across the globe, especially for high
value crops. The total loss of crops to pest bird damage in Australia is estimated to be at around
$300 million annually [1]. Various pest bird damage control methods have been developed in
the past few decades. These methods, such as netting, shooting and artificial scaring tactics, are
either ineffective or not economically viable. In addition, these solutions are temporary, the pest
bird problem persists as soon as the treatment is stopped. In fact, the most effective long term
solution is natural predation. Studies have shown that by training natural predatory birds such
as falcons and eagles, the predator-prey population dynamics can be stabilized on a large scale
[2]. However, the cost for hiring a trained falconer is not economically viable for most farms
[3]. Hence, there is interest in designing a biomimetic pest bird damage control system that is
both economical and as effective as natural predation.
With the recent increase in popularity and development of UAV technologies [4], many
individuals, research groups and companies are starting to explore the idea of using small UAVs
to control damage caused by pest birds [5-8]. Many of these systems employ one or a
combination of a few biomimetic elements to attempt to achieve the same effectiveness of
natural predation [5-8]. These biomimetic elements range from using a simple audio system to
broadcast predatory bird cries to combining predatory bird appearance, movement and behavior
on a single UAV platform. This paper provides a broad overview of the current biomimetic
design implementations on UAVs for pest bird damage control in agriculture.
Current Pest Bird Control Methods
There are many bird control strategies currently employed by farmers around the world [9,10].
These control strategies can be generally divided into four categories: scare tactics, population
reduction methods, exclusion methods, and natural predation.

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Scare Tactics
These methods rely on a scare stimulus that presents an unusual, sudden or dangerous event to
the birds [9]. There are many possible scare stimuli, and some of them are related to natural
predation. Stimuli are required to be life-like, highly visible or loud, and in motion to be
effective [9]. Some non-biomimetic examples are spinning metal strips and loud air-cannons.
Scaring devices that include biomimetic elements are predatory bird silhouettes, speakers that
broadcast distress calls, and remote controlled (RC) aircraft carrying predatory bird features [9].
RC aircraft can perform continuous unexpected motions, the RC aircraft itself can be considered
a visual scare stimulus. The issue with scare tactics is that birds becoming habituated to them.
Solutions to habituation include irregularity in the scaring pattern, combining visual and
acoustic scaring methods, and presenting a real threat to the birds [9].
Population Reduction Methods
Population reduction methods are usually lethal, such as poisoning, shooting and capturing [9].
The intention is to reduce the total number of pest birds in the local area, hence the damage to
the crops should reduce accordingly. Shooting is in fact the most common method in Australia
[9]. However, studies have shown that population reduction is often ineffective [9]. There are
also legal issues in some countries with these methods, as some protected species can be
accidently injured or killed [9].
Exclusion Methods
Exclusion methods control pest bird damage by preventing birds from accessing the crops.
Some popular methods include chemical repellents, nets over the crops, or using sleeves to
cover individual crops [9]. Exclusion methods are highly effective. However, netting and
sleeving are labour intensive. They can also hinder crop inspection and harvesting, which
translates into high cost to the farmers [9].
Natural Predation
Natural predation utilises birds of prey such as falcons and eagles to hunt pest birds near the
farms. These predatory birds are usually highly trained by falconers who are sometimes
employed by farmers [9]. Natural predation is an effective but expensive control method. This
method is most effective when multiple predatory birds are used, making the cost associated
with employing falconers uneconomical in most situations [10,11].
Pest Bird Control UAVs
The literature suggests that none of the existing pest bird control methods are both effective and
economical means for protecting agriculture from birds. One of the potential solutions is to
mimic natural predation. Some studies have shown that UAVs mimicking natural predatory
birds are effective in scaring pest birds [5]. Coincidently, the interest in using UAVs for this
application is growing [12,13]. The cost of human UAV operators can also be eliminated with
the fast-growing autonomous technologies.
The small UAVs mentioned in this paper refer to power-driven, reusable, remotely operated or
autonomous aircraft. In the past, UAVs were expensive and sophisticated machines primarily
used by the military. UAVs have become affordable to researchers and consumers thanks to the
development of high energy density batteries, miniaturised electronics, and fast wireless
networking equipment [4]. The most common UAV types are fixed-wing, rotary-wing (e.g.

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quadcopters, helicopters), and fixed-wing with vertical take-off and landing (VTOL)
capabilities.
Typical Biomimetic Designs
The typical biomimetic designs implemented using UAVs for bird control are introduced and
compared in this section. Due to commercial interests, it is difficult to compare the effectiveness
of these designs directly from literature survey.
Appearance Mimicking Designs
Appearance mimicking is the simplest form of biomimetic design. Feather patterns, colour
patterns, and large eye spots are typical features used. The aircraft structure is sometimes
modified to resemble predatory bird shapes as well, such as wingtip and tail designs. These
have been implemented by farm owners in the past on static objects. Kites or wooden boards
with predator-shaped silhouettes are still used today in agriculture for pest bird control (Fig. 1).
Fig. 1: Scare Hawk Decoy by Birds Off – A commercial product for bird control, an example
of appearance mimicking that uses static silhouette [14]
Unfortunately, the predictable and static nature of the silhouette render them ineffective over
time, as birds habituate to them very quickly. Appearance mimicking on UAVs are more
effective as autonomous or remotely-piloted UAVs can exhibit unpredictable behaviour, which
cause a significant delay to habituation.
Appearance mimicking has been adopted by researchers (Fig. 2 [15]) as well as industries (Fig.
3 [16]). One common feature is that appearance mimicking is usually used on fixed-wing
UAVs. This is due to the fact that conventional fixed-wing aircraft have large wings and small
tails that resemble the typical shape of predators. It is therefore easier to make the mimicked
appearance more life-like.
Fig. 2: A biomimetic autonomous aircraft for bird management from Royal Melbourne
Institute of Technology (RMIT), Australia [15]

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Fig. 3: Shepherd, a remotely piloted UAV designed by Ecotactical Technologies for
commercial bird control [16]
Flapping Wing Designs
Another form of visual mimicking is to replicate the wing flapping motion of predatory birds.
A flapping design is quite complex. While replicating life-like motion, the design must still
provide appropriate aerodynamic lift and propulsion. This design is much more difficult to
implement and much less common in commercial practice. An example of implementing the
flapping wing approach is Robirds by the company Clear Flight Solutions (Fig. 4). The
company claimed a maximum of 50% reduction in bird numbers in some experiments [17].
Fig. 4: Robirds – Designed by Clear Flight Solutions for pest bird control, equipped with
flapping wings and appearance of birds of prey [18]
Audio Mimicking Designs
Apart from visual cues, birds detect the presence of predators by sound as well. This has inspired
products such as the Sparrow Repeller, which is a system consisting of loud speakers that
broadcast recordings of distress, predator and harassment calls [18], designed to give the
impression of a falcon attacking a sparrow.
The audio recording combined with the unpredictable movement and the physical presence of
the UAVs is effective against numerous bird types as claimed by some manufacturers [6,7].
Systems such as Sparrow Repeller can be easily implemented onto rotary UAVs, such as the
Vulcan UAV Bird Control Drone “The ScareCrow” in Fig. 5. On the other hand, these systems
are more challenging to implement on small fixed-wing UAVs due to the size. Birds will also
habituate to the audio eventually if no real threat is present.

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Fig. 5: Left: BirdGard Sparrow Repeller. Right: Vulcan UAV Bird Control Drone – “The
ScarCrow” quadcopter, with BirdGard Sparrow Repeller attached.
Flight Pattern and Behaviour Mimicking Designs
A different approach to the aforementioned designs is to mimic the flight pattern and behaviour
of predatory birds. An interview with a North American wildlife biologist conducted by a
research group from Oregon State University revealed that, the flight pattern and behaviour are
as important as the appearance and sound [5]. More importantly, the flight pattern and behaviour
should adhere to that of the local predatory bird species.
Fig. 6: Illustration of flight path designed by researchers at Oregon State University [5].
In these experiments, the researchers programmed a fixed-wing glider UAV to mimic the flight
patterns of a Cooper’s Hawk [5]. The Cooper’s Hawk species prefer to perch and wait for
appetizing prey, then swoop down for the kill [5]. The glider is programmed to loiter behind
trees while gaining altitude, and then swoop down towards the vineyard using GPS coordinates,
as illustrated in Fig. 6. The issues with the system is that no information of the bird location is
available to the UAVs. While they claimed to achieve successful results from initial trials, it is
likely to be inefficient if pest birds are not targeted more directly [5].
Potential Pathways to Resolve Current Limitations
It is evident from this literature survey that there are limitations with existing biomimetic
designs for UAV-based pest bird control. Appearance mimicking and audio mimicking designs
are simple but pest birds eventually habituate. Flapping wing designs are mechanically
complicated to satisfy both aerodynamic and propulsion requirements. Flight pattern mimicking
designs are effective but not well targeted.
There are several potential pathways to resolve these limitations. Pest bird location can be
identified with a system that consists of bird-scaring UAVs, ground sensors and a ground
control station (GCS). The ground sensors can be radar or cameras with vision processing
modules that detect birds and inform the GCS where most of the pest birds are located. This

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17th Australian Aerospace Congress, 26-28 February 2017, Melbourne
information can then be transformed into waypoints for the UAVs. The UAVs can also be
equipped with cameras with on-board processing. The cameras could aid in precision navigation
during the swoop manoeuvres, so that it is more apparent to the birds that the UAVs are
intentionally attacking them.
Any UAV type could be used for this approach, but ideally, flapping wing designs combined
with appearance and audio mimicking should be used to maximise effectiveness. To eliminate
the difficulties with flapping wing designs, the aircraft can be replaced by a bird model with
simple flapping wings that is towed or mounted to a multi-rotor. By doing so, the flapping wings
do not have to provide lift and propulsion, which reduces the complexity significantly. Such a
system could also mimic the predatory bird appearance more accurately.
Conclusion
Pest bird damage in agriculture is a persistent problem across the globe, and existing solutions
are not adequately addressing the issues. Many methods, such as scaring, trapping, excluding,
and natural predation have been developed and tried. These methods, however, have
limitations that have not yet been overcome. The literature demonstrates that the most
effective solutions, even if temporary, are biomimetic designs. The emergence of high-
energy-density lithium polymer batteries and miniaturized electronics has accelerated the
availability of small UAVs, and there is much promise in the application of this technology
for bird damage control in agriculture.
This survey has discussed four approach categories for biomimetic bird control: appearance
mimicking, flapping wings, audio mimicking, and behaviour mimicking. While commercial
products employing some of these methods claim to work, other studies indicate that pest
birds adapt quickly. A novel biomimetic approach is proposed, which incorporates the
previous methods in a “smart” system that targets pest birds directly and takes advantages of
recent developments in miniaturisation and energy storage density to combine all four
approaches in a more natural predator-like design.

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References
1. J. Tracry, M. Bomford, Q. Hart, G. Saunder, and R. Sinclair, Managing Brid Damage
to Fruit and Other Horticultural Crops. Canberra: Bureau of Rural Sciences, 2007.
2. W. Cresswell, Non-lethal effects of predation in birds, Ibis, vol. 150, no. 1, pp. 3-17
3. J. P. Tracey, Ecology, impact and management of pest birds, PhD thesis, University of
York Environment Department, Sep. 2012.
4. H. Chao, Y. Cao, and Y. Chen, Autopilots for small unmanned aerial vehicles: A survey,
International Journal of Control, Automation, and Systems, pp. 36-44, 2010.
5. B. A. Grimm, B. A. Lahneman, P. B. Cathcart, R. C. Elgin, G. L. Meshnik, and J. P.
Parmigiani, “Autonomous unmanned aerial vehicle system for controlling pest bird
population in vineyards,” in ASME International Mechanical Engineering Congress
`and Exposition, 2012, pp. 499–505.
6. Rise Above. (2016). Vulcan UAV Bird Control Drone – ‘The ScareCrow’, [Online].
Available: http://www.riseabove.com.au/products/vulcan-uav-bird-control-drone-the-
scarecrow.html. [Accessed 2016]
7. Bird-X. (2016). Bird-X Announces Fully Autonomous Bird Control Drone, [Online].
Available: https://www.bird-x.com/bird-x-announces-fully-autonomous-bird-control-
drone-news-78.php. [Accessed 2016]
8. C. Anderson. (2014). Robo-birds to scare away real ones, [Online]. Available:
http://diydrones.com/profiles/blogs/robo-birds-to-scare-away-real-ones. [Accessed
2016]
9. J. Tracey, M. Bomford, Q. Hart, G. Saunders, and R. Sinclair, Managing Bird Damage
to Fruit and Other Horticultureal Crops. Canberra: Bureau of Rural Sciences, 2007.
10. D. Marcsik and D. Clarke, An evaluation of control methods to reduce winged vertebrate
pest damage to horticultural crops in the Top End. Department of Primary Industry,
Fisheries, and the Conservation Commission of the Northern Territory, 1997.
11. Lahneman, Brooke, Innovative Bird Pest Management Practices for Vineyards, vol. 17,
23 Sept, 2011, pp. 124-154.
12. The University of Qeensland, Australia. (2016). UAV Scarevoew – Using drones to
mimic falcon flight patterns as a pest management strategy, [Online]. Available:
http://www.uq.edu.au/agriculture/uav-scarecrow-using-drones-to-mimic-falcon-flight-
patterns-as-a-pest-management-strategy. [Accessed 2016]
13. H. Brown. (2009). Bird chaser – DIY Drone? Protect an orchard from birds, [Online].
Available: http://diydrones.com/forum/topics/bird-chaser-diy-drone-protect. [Accessed
2016]
14. Birds Off (2016). Scare Hawk Decoy – As Seen With Dr Harry On Better Homes and
Gardens!, [Online]. Available: http://birdsoff.com.au/scare-hawk-decoy-as-seen-with-
dr-harry-on-better-homes-and-gardens/. [Accessed 2016]

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15. B. Muller, R. Clothier, S. Watkins, and A. Fisher, Design of Bio-Inspired Autonomous
Aircraft for Bird Management, in Proceedings of the 16th Australian International
Aerospace Congress (AIAC16), Engineers Australia, 2015: pp. 370-377.
16. Ecotactical Technologies. (2016). Shepherd, designed by Ecotactical Technologies has
achieve to fuse the effectiveness from the falconry with the reliability and functioning of
a machine, [Online]. Available: http://www.ecotactical.com/eng/productos.html.
[Accessed 2016]
17. Clear Flight Solutions. (2016). Robirds, [Online]. Available:
https://clearflightsolutions.com/methods/robirds. [Accessed 2016]
18. Bird Gard Australia. (2016). Sparrow Repelle, [Online]. Available:
http://www.birdgard.com.au/pest-control/sparrow-repeller. [Accessed 2016]