Distraction displays, also known as diversionary displays, or paratrepsis [1] [2] are anti-predator behaviors used to attract the attention of an enemy away from something, typically the nest or young, that is being protected by a parent. [3] [4] Distraction displays are sometimes classified more generically under "nest protection behaviors" along with aggressive displays such as mobbing. [5] These displays have been studied most extensively in bird species, [1] but also have been documented in populations of stickleback fish [6] [7] [8] [9] [10] and in some mammal species. [11] [12]
Distraction displays frequently take the form of injury-feigning. [4] However, animals may also imitate the behavior of a small rodent or alternative prey item for the predator; [13] [14] [15] imitate young [12] or nesting behaviors such as brooding (to cause confusion as to the true location of the nest), [13] mimic foraging behaviors away from the nest, [9] or simply draw attention to oneself. [1]
The behaviour was first described by Aristotle in his History of Animals . [16]
David Lack postulated that distraction displays simply resulted from the bird's alarm at having been flushed from the nest and had no decoy purpose. He noted a case in the European nightjar, when a bird led him around the nest several times but made no attempt to lure him away. He additionally noted courtship displays mixed with the distraction displays of the bird, suggesting that distraction display is not a purposeful action unto itself, and observed that the display became less vigorous the more frequently he visited the nest, as would be expected if the display were a response driven by fear and surprise. [17]
Other researchers, including Edward Allworthy Armstrong, [1] have taken issue with these arguments.[ when? ] While Armstrong acknowledged that displaying animals could make mistakes, as Lack's nightjar seems to have done in leading him around the nest, he attributed such mistakes not to paralytic fear but to a conflict of interest between self-preservation and reproductive or enemy attack impulses: the bird at once experiences a drive to lure the predator away and also to directly guard the young. [1] Armstrong also thought that the incorporation of sexual and threat displays into the distraction display did not necessarily represent a mistake on the part of the animal, but "might make the display more effective by increasing its conspicuousness". [1] Finally, the observation of less vigorous displays due to repeated nest approaches does not preclude the parent animal simply learning that the human is not a threat to its young. Jeffrey Walters provided evidence that lapwings possessed the ability to distinguish between different types of predators of varying threat levels, a behavior which is presumably learned, [18] perhaps through cultural transmission. [19]
Armstrong additionally noted that displaying animals were rarely captured by predators, as would be expected if the display were truly uncontrolled, and that the movements seemed to show signs of some sort of control by the animal, although likely not conscious, intelligent control. [1] One example of apparent control is attention seemingly paid to routes used by the displaying animal when moving away from the nest. [1] Furthermore, researchers have noted parent animals moving towards the predator during the display. [1] [14] [20] While some of these cases could be attributed to mistakes made during "partial paralysis", in the case described by Wiklund and Stigh, snowy owls consistently walked or ran towards the predator while displaying, suggesting that the action was deliberate. [20]
An additional hypothesis in alignment with Armstrong's ideas about conflicting impulses suggests that the incorporation of sexual and threat displays into the distraction display may represent displacement. Displacement occurs when an animal, unable to satisfy two conflicting impulses, may initiate an out-of-context behavior to "vent". [21] If a displacement behavior served an adaptive function, such as increased survival of the young, then it may have experienced positive selection and become ritualized and stereotyped in its new context. [1]
In any case, there are some forms of distraction display which may in fact have evolved from stress responses, an idea more in alignment with Lack's hypothesis. One of these is the "rodent-run" display, in which a bird fluffs its feathers to mimic the fur of a rodent and scurries away from the nest. It is possible that this display originates from a feather ruffling reflex to alarm. [14]
There are several conditions in which distraction display may be advantageous to the animal, such that the incorporation of displacement or stress behaviors into offspring defense will most likely undergo positive selection. Most such cases depend upon the condition or location of the nest: distraction display has tended to evolve in species whose nests alone do not provide a substantial physical barrier to predators, and in those that nest on exposed terrain or close to the ground. [4] If the nest is on open terrain, the parent may perceive predators at a greater distance and be able to leave the nest and begin displaying before the predator is in sufficient proximity to locate the nest. [22] [4] Ground-nesting birds employ different defensive behaviors as part of their antipredator strategies because they nest where a wide range of predators have access.
It has been shown that for Kentish plovers there is a positive correlation between male and female defense behaviors within pairs and that nests in which parents invested more on defense survived longer. [23] Furthermore, if the nest is on or near the ground, the parent may be able to display more effectively; Armstrong noted the relative rarity in the literature of distraction display in arboreal-nesting species, and attributed this to the difficulty of displaying convincingly while on a branch. [4] Nonetheless, there have been anecdotal reports of warblers, which nest arboreally, dropping to the ground to perform a distraction display when disturbed, as well as displaying along a tree branch. [24] In addition, distraction display tends to be most adaptive when animals nest solitarily, as solitary nesters lack the opportunity for mobbing a predator or otherwise performing communal defense, although some species have been observed to display in groups. [4] Finally, distraction display tends to be adaptive when diurnal predation by visually-stimulated predators takes place (as these predators are most likely to notice the visual display). [4]
Distraction display has been most extensively studied in birds. [4] It has been observed in many species, including passerines [15] [24] [25] [26] and non-passerines, [20] [27] [28] and has been particularly well documented in the Charadriiformes. [29] [13] [14] [18] [30]
Injury-feigning, including broken-wing [31] [2] and impeded flight [4] [13] displays, is one of the more common forms of distraction. [1] In broken-wing displays, birds that are at the nest walk away from it with wings quivering so as to appear as an easy target for a predator. [13] [25] Such injury-feigning displays are particularly well known in nesting waders and plovers, but also have been documented in other species, including snowy owls, [20] the alpine accentor, [25] and the mourning dove. [32] Impeded flight displays additionally may suggest an injured wing, but through an airborne display.
False brooding is an approach used by plovers. The bird moves away from the nest site and crouches on the ground so as to appear to be sitting at a nonexistent nest and allows the predator to approach closely before escaping. [13] [18] [30] Another display seen in plovers, [13] as well as some passerine birds, [14] [15] is the rodent run, in which the nesting bird ruffles its back feathers, crouches, and runs away from the predator. This display resembles the flight response of a small rodent. [14]
It has additionally been postulated that threat displays, such as gaping by the Caprimulgidae and wing-extension by the killdeer, and sexual displays, such as courtship dancing by stilts, can become incorporated into distraction displays where the bird is feigning injury. In both cases the incorporated components may increase conspicuousness, resulting in a more effective distraction display. [1]
Stickleback fish have been documented performing distraction displays. A nesting male three-spined stickleback, when approached by a group of conspecifics, will perform a distraction display by digging or pointing into the substrate away from the nest in order to protect his eggs from cannibalism. [9] There have been two explanations proposed for this behavior. One hypothesis is that the display arose from a courtship behavior in which the male normally "points" an approaching female towards his nest so that she may lay her eggs within it. [10] Therefore, pointing at the sediment away from a nest containing eggs may divert a cannibalistic female's attention through sexual cues. [10] A second hypothesis is that the stickleback distraction display arose from displaced foraging behavior and as such represents faux-foraging. [8] In support of this hypothesis was the finding that all-male, all-female, and mixed foraging groups responded equally to the display, which would not be expected if it were indeed mimicking a sexual display. [9]
Though rarely documented in mammals, a few instances of distraction display have appeared in the literature. One researcher documented a distraction display performed by a female red squirrel in order to protect her young. When the nest was approached, the female attempted to lead the researcher away through the trees using a ventriloquistic call that resembled the cries of the young. [12] An additional study documented distraction display in Mentawai langurs, whereby a male will call loudly and bounce on branches while the female and young are able to quietly hide. [11]
While animals performing distraction displays are rarely documented as being killed, risks to the displaying animal do exist. [33] One researcher observed and documented an instance in which a second predator became attracted to an animal already performing a distraction display. The displaying animal was killed by the second predator. [33]
Additionally, it has been shown that some predators are "smart", or have learned to recognize that distraction displays indicate a nearby nest. One study recorded a red fox that increased its searching behavior in response to the distraction display of a grouse and eventually found and killed the grouse nestlings. [28]
Given these risks, an animal must decide when distraction display is an appropriate response to a predator. Researchers have found several important factors that appear to influence the decision to use a distraction display and the intensity of the display, although it is not evident that these factors are taken into consideration consciously by the displaying animal. [21] [30]
Several considerations involving the predator have been shown to be important, including the distance of the predator from the nest. Intensity of display has been shown to decrease as the distance of the predator from the nest increases, perhaps representing the balancing of risk to the displaying parent and to the vulnerable young. [26] The type of predator has also been shown to be of importance, [18] with birds tending to display most intensely to ground-dwelling carnivores and less intensely to humans and flying predators. [13] [23] [34] Finally, the number of potential predators has also been shown to be important in sticklebacks, in which frequency of distraction displaying by the male is positively correlated with the number of conspecifics in a foraging shoal. [8]
In addition, the presence of a second parent at the nest correlates with increased display intensity, perhaps representing a diluted predation risk. [27] The number of potential extra-pair mobbers has also been shown to marginally increase the intensity of the display, again representing a possible dilution of risk to each of the animals engaging in the distraction. [26]
Third, the timing of distraction display as a correlate of nestling age has been a matter of particular interest in birds, with study results showing that the age at which displays are performed differs in species with precocial and altricial young. In species with precocial young, distraction display is most frequent just after hatching, while in altricial young, it is most frequent just before fledging. [15] [25] [26] This may represent a greater tendency to display at the times when parental investment in young is greatest, and the young are still very vulnerable. [25] However, some studies [27] have failed to find any correlation between the cost of replacing a brood (a measure of parental investment) and the frequency of distraction display.
Lastly, game theory has been employed to explain how grouse may decide to display or not based on proxies for the abundance of "smart" predators, such as abundance of rodents in the preceding year. [28] In this particular study, it was assumed that a greater abundance of rodents in one year may result in higher birth rates among foxes, which feed on the rodents, and therefore a greater population of one-year-old foxes in the following year. Yearling foxes are not yet experienced enough grouse hunters to be considered "smart". As such, distraction display may be a profitable strategy for the grouse in years following rodent population booms, as there is less risk of encountering a "smart" predator. However, a low rodent population in a given year may result in lower birth rates among foxes for that year, thereby resulting in a higher proportion of older, more experienced foxes in the population in the following year. In such a case, grouse may profit from not displaying, as they are more likely to encounter a "smart" predator. [28]
The killdeer is a large plover found in the Americas. It gets its name from its shrill, two-syllable call, which is often heard. It was described and given its current scientific name in 1758 by Carl Linnaeus in the 10th edition of his Systema Naturae. Three subspecies are described. Its upperparts are mostly brown with rufous fringes, the head has patches of white and black, and two black bands cross the breast. The belly and the rest of the breast are white. The nominate subspecies breeds from southeastern Alaska and southern Canada to Mexico. It is seen year-round in the southern half of its breeding range; the subspecies C. v. ternominatus is resident in the West Indies, and C. v. peruvianus inhabits Peru and surrounding South American countries throughout the year. North American breeders winter from their resident range south to Central America, the West Indies, and the northernmost portions of South America.
The piping plover is a small sand-colored, sparrow-sized shorebird that nests and feeds along coastal sand and gravel beaches in North America. The adult has yellow-orange-red legs, a black band across the forehead from eye to eye, and a black stripe running along the breast line. This chest band is usually thicker in males during the breeding season, and it is the only reliable way to tell the sexes apart. The bird is difficult to see when it is standing still, as it blends well with open, sandy beach habitats. It typically runs in short, quick spurts and then stops.
Foraging is searching for wild food resources. It affects an animal's fitness because it plays an important role in an animal's ability to survive and reproduce. Foraging theory is a branch of behavioral ecology that studies the foraging behavior of animals in response to the environment where the animal lives.
The three-spined stickleback is a fish native to most inland and coastal waters north of 30°N. It has long been a subject of scientific study for many reasons. It shows great morphological variation throughout its range, ideal for questions about evolution and population genetics. Many populations are anadromous and very tolerant of changes in salinity, a subject of interest to physiologists. It displays elaborate breeding behavior and it can be social making it a popular subject of inquiry in fish ethology and behavioral ecology. Its antipredator adaptations, host-parasite interactions, sensory physiology, reproductive physiology, and endocrinology have also been much studied. Facilitating these studies is the fact that the three-spined stickleback is easy to find in nature and easy to keep in aquaria.
A bird nest is the spot in which a bird lays and incubates its eggs and raises its young. Although the term popularly refers to a specific structure made by the bird itself—such as the grassy cup nest of the American robin or Eurasian blackbird, or the elaborately woven hanging nest of the Montezuma oropendola or the village weaver—that is too restrictive a definition. For some species, a nest is simply a shallow depression made in sand; for others, it is the knot-hole left by a broken branch, a burrow dug into the ground, a chamber drilled into a tree, an enormous rotting pile of vegetation and earth, a shelf made of dried saliva or a mud dome with an entrance tunnel. The smallest bird nests are those of some hummingbirds, tiny cups which can be a mere 2 cm (0.8 in) across and 2–3 cm (0.8–1.2 in) high. At the other extreme, some nest mounds built by the dusky scrubfowl measure more than 11 m (36 ft) in diameter and stand nearly 5 m (16 ft) tall. The study of birds' nests is known as caliology.
Kittlitz's plover is a small shorebird in the family Charadriidae that breeds near coastal and inland saltmarshes, sandy or muddy riverbanks or alkaline grasslands with short vegetation. It is native to much of Sub-Saharan Africa, the Nile Delta and Madagascar. It is thought to be mainly polygamous and has monomorphic plumage.
"Fixed action pattern" is an ethological term describing an instinctive behavioral sequence that is highly stereotyped and species-characteristic. Fixed action patterns are said to be produced by the innate releasing mechanism, a "hard-wired" neural network, in response to a sign/key stimulus or releaser. Once released, a fixed action pattern runs to completion.
Optimal foraging theory (OFT) is a behavioral ecology model that helps predict how an animal behaves when searching for food. Although obtaining food provides the animal with energy, searching for and capturing the food require both energy and time. To maximize fitness, an animal adopts a foraging strategy that provides the most benefit (energy) for the lowest cost, maximizing the net energy gained. OFT helps predict the best strategy that an animal can use to achieve this goal.
The white-fronted plover or white-fronted sandplover is a small shorebird of the family Charadriidae that inhabits sandy beaches, dunes, mudflats and the shores of rivers and lakes in sub-saharan Africa and Madagascar. It nests in small shallow scrapes in the ground and lays clutches of one to three eggs. The species is monogamous and long-lived, with a life expectancy of approximately 12 years. The vast majority of pairs that mate together stay together during the following years of breeding and retain the same territory. The white-fronted plover has a similar appearance to the Kentish plover, with a white fore crown and dark bands connecting the eyes to the bill.
The Kentish plover is a small wader of the family Charadriidae that breeds on the shores of saline lakes, lagoons, and coasts, populating sand dunes, marshes, semi-arid desert, and tundra. Both male and female birds have pale plumages with a white underside, grey/brown back, dark legs and a dark bill; however, additionally the male birds also exhibit very dark incomplete breast bands, and dark markings either side of their head, therefore the Kentish plover is regarded as sexually dimorphic.
Mobbing in animals is an antipredator adaptation in which individuals of prey species cooperatively attack or harass a predator, usually to protect their offspring. A simple definition of mobbing is an assemblage of individuals around a potentially dangerous predator. This is most frequently seen in birds, though it is also known to occur in many other animals such as the meerkat and some bovines. While mobbing has evolved independently in many species, it only tends to be present in those whose young are frequently preyed upon. This behavior may complement cryptic adaptations in the offspring themselves, such as camouflage and hiding. Mobbing calls may be used to summon nearby individuals to cooperate in the attack.
A bird colony is a large congregation of individuals of one or more species of bird that nest or roost in proximity at a particular location. Many kinds of birds are known to congregate in groups of varying size; a congregation of nesting birds is called a breeding colony. Colonial nesting birds include seabirds such as auks and albatrosses; wetland species such as herons; and a few passerines such as weaverbirds, certain blackbirds, and some swallows. A group of birds congregating for rest is called a communal roost. Evidence of colonial nesting has been found in non-neornithine birds (Enantiornithes), in sediments from the Late Cretaceous (Maastrichtian) of Romania.
The silky-tailed nightjar is a species of nightjar birds in the family Caprimulgidae. It is found in Brazil, Argentina, Bolivia, Paraguay, and Peru. Its natural habitat is subtropical or tropical moist lowland forests.
The long-toed lapwing , also known as the long-toed plover, is a species of wading bird in the lapwing subfamily, within the family Charadriidae. It is mainly sedentary and found across central and eastern Africa, from Chad and South Sudan in the north to Mozambique in the southeast of its range. It is one of 13 species of ground-nesting lapwings found in Africa.
Nesting behavior refers to an instinct in animals during reproduction to prepare a place with optimal conditions for offspring. The nesting place provides protection against predators and competitors that mean to exploit or kill offspring. It also provides protection against the physical environment.
Collective animal behaviour is a form of social behavior involving the coordinated behavior of large groups of similar animals as well as emergent properties of these groups. This can include the costs and benefits of group membership, the transfer of information, decision-making process, locomotion and synchronization of the group. Studying the principles of collective animal behavior has relevance to human engineering problems through the philosophy of biomimetics. For instance, determining the rules by which an individual animal navigates relative to its neighbors in a group can lead to advances in the deployment and control of groups of swimming or flying micro-robots such as UAVs.
Fish intelligence is "the resultant of the process of acquiring, storing in memory, retrieving, combining, comparing, and using in new contexts information and conceptual skills" as it applies to fish. Due to a common perception amongst researchers that Teleost fish are "primitive" compared to mammals and birds, there has been much less research into fish cognition than into those types of animals, and much remains unknown about fish cognition, though evidence of complex navigational skills such as cognitive maps is increasing.
Deception in animals is the voluntary or involuntary transmission of misinformation by one animal to another, of the same or different species, in a way that misleads the other animal. Robert Mitchell identifies four levels of deception in animals. At the first level, as with protective mimicry like false eyespots and camouflage, the action or display is inbuilt. At the second level, an animal performs a programmed act of behaviour, as when a prey animal feigns death to avoid being eaten. At the third level, the deceptive behaviour is at least partially learnt, as when a bird puts on a distraction display, feigning injury to lure a predator away from a nest. Fourth level deception involves recognition of the other animal's beliefs, as when a chimpanzee tactically misleads other chimpanzees to prevent their discovering a food source.
Allofeeding is a type of food sharing behaviour observed in cooperatively breeding species of birds. Allofeeding refers to a parent, sibling or unrelated adult bird feeding altricial hatchlings, which are dependent on parental care for their survival. Allofeeding also refers to food sharing between adults of the same species. Allofeeding can occur between mates during mating rituals, courtship, egg laying or incubation, between peers of the same species, or as a form of parental care.
Egg predation or ovivory is a feeding strategy in many groups of animals (ovivores) in which they consume eggs. Since a fertilized egg represents a complete organism at one stage of its life cycle, eating an egg is a form of predation, the killing of another organism for food.