Jasni, 2013), Ant Colony Optimization (Dorigo & Stutzle, 2004), Artificial Fish Swarm
Algorithm (Gao, Wu, Zenger, & Huang, 2010), Artificial Bee Colony (Karaboga & Basturk,
2007), Glowworm Swarm Optimization (Krishnanand & Ghose, 2009), Cuckoo Search (Yang &
Deb, 2014), Bat Algorithm (Yang, 2010), Krill Herd (Gandomi & Alavi, 2012), etc. were
inspired by the swarm intelligence of social animals. Inspired by the plant, Invasive Weed
Optimization (Mehrabian & Lucas, 2006) and Flower Pollination Algorithm (Yang,
Karamanoglu, & He, 2014 ) were designed. Harmony Search (Manjarres et al., 2013), Charged
System Search (Kaveh & Talatahari, 2010), Brain Storm Optimization (Shi, 2011), etc. were
inspired by physical principles and nature phenomena.
Though many algorithms were developed to deal with optimisation applications, there still
exists no universal algorithm. Thus, the research of finding more efficient algorithms is still in
progress.
In this paper, a new bio-inspired algorithm, namely Bird Swarm Algorithm (BSA), is
proposed as a new optimisation method. BSA is simplification of the social behaviours and
social interactions in bird swarms. It mimics the birds’ foraging behaviour, vigilance behaviour
and flight behaviour. Thus, the swarm intelligence can be effici ently extracted from the bird
swarms to optimise problems.
The rest of the paper is organised as follows. Section 2 illustrates the details of BSA.
Simulations and comparisons are presented in Section 3. Finally, some conclusions and
discussions are given in Section 4.
2. The Bird Swarm Algorithm
2.1 Biological fundamentals
Many bird species are gregarious, such as finches. They may roost communally, forage and fly in
flocks (Anderson, 2006). These behaviour s are considered as emergent behaviour s arising from
simple rules such as separation, alignment and cohesion. Through the simplest social interaction,
the swarm behaviours can develop complex motions and interactions.
Foraging in flocks, birds may get more information than their own sense s can gather, and
have survival advantage and good foraging efficiency. If one bird finds some food patches,
others may feed from them (Kennedy, Eberhart, & Shi, 2001). While foraging, birds often
aggregate in response to predation threat (Krause & Ruxton, 2002). They frequently raise their
heads and scan their surroundings. These behaviours, interpreted as vigilance behaviour
(Anderson, 2006), may be conducive to detecting predators (Lima & Dill, 1990). Studies
showed that birds would randomly choose between foraging and keeping vigilance (Bednekoff
& Lima, 1998). Birds often give alarm calls when they detect a predator (Pulliam, Pyke, Caraco,
& Pulliam, 1982). Thus, the whole group would fly off together. It can reasonably conclude that
birds in a flock have a better chance of detecting a potential threat than a single one. A reduction
in individual vigilance with an increase in group size is so widespread in many birds (Ekman,
1987; Elgar & Catterall, 1981; Sullivan, 1984). In other words, a bird can spend more time
foraging as group size increases without affecting the increased risk of being attacked by the
predator (Beauchamp, 1998; Roberts, 2003).
The birds on the periphery of a group have more chance of being attacked by the predators
than those in the centre. Studies suggested that animals foraging in the centre of flock may move
to their neighbours to protect themselves from being attacked by the predators (Pulliam, 1973).
Each bird would try to move towards the centre of the flock as they perceive it. This motion,
however, may be affected by the interference induced by competing among the bird swarms
(Beauchamp, 2003). Thus, birds may not directly move towards the centre of the swarm.
X.-B. Meng et al.2
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