Publications by category
Journal articles
Caves E, Troscianko J, Kelley L (In Press). A customizable, low-cost optomotor apparatus: a powerful tool for behaviourally measuring visual capability.
Methods in Ecology and Evolution Full text.
Kelley LA (In Press). California scrub-jays reduce visual cues available to potential pilferers by matching food colour to caching substrate.
Biology Letters Full text.
Galloway J, Green SD, Stevens M, Kelley L (In Press). Finding a signal hidden among noise: how can predators overcome camouflage strategies?.
Philosophical Transactions of the Royal Society B: Biological Sciences Full text.
Goumas M, Kelley L, Boogert N (In Press). Herring gull aversion to gaze in urban and rural human settlements.
Animal Behaviour Full text.
Kelley LA (In Press). How do great bowerbirds construct perspective illusions?.
Royal Society Open Science Full text.
Hughes AE, Griffiths D, Troscianko J, Kelley LA (In Press). No evidence for motion dazzle in an evolutionary citizen science game.
Abstract:
No evidence for motion dazzle in an evolutionary citizen science game
AbstractThe motion dazzle hypothesis posits that high contrast geometric patterns can cause difficulties in tracking a moving target, and has been argued to explain the patterning of animals such as zebras. Research to date has only tested a small number of patterns, offering equivocal support for the hypothesis. Here, we take a genetic programming approach to allow patterns to evolve based on their fitness (time taken to capture) and thus find the optimal strategy for providing protection when moving. Our ‘Dazzle Bug’ citizen science game tested over 1.5 million targets in a touch screen game at a popular visitor attraction. Surprisingly, we found that targets lost pattern elements during evolution and became closely background matching. Modelling results suggested that targets with lower motion energy were harder to catch. Our results indicate that low contrast, featureless targets offer the greatest protection against capture when in motion, challenging the motion dazzle hypothesis.
Abstract.
Kelley L, Caves E (In Press). Sex differences in behavioural and anatomical estimates of visual acuity in the green swordtail Xiphophorus helleri.
Journal of Experimental BiologyAbstract:
Sex differences in behavioural and anatomical estimates of visual acuity in the green swordtail Xiphophorus helleri
Among fishes in the family Poeciliidae, signals such as colour patterns, ornaments, and courtship displays play important roles in mate choice and male-male competition. Despite this, visual capabilities in Poeciliids are understudied, in particular visual acuity, the ability to resolve detail. We used three methods to quantify visual acuity in male and female green swordtails (Xiphophorus helleri), a species in which body size and the length of the male’s extended caudal fin (‘sword’) serve as assessment signals during mate choice and agonistic encounters. Topographic distribution of retinal ganglion cells (RGC) was similar in all individuals and characterized by areas of high cell densities located centro-temporally and nasally, as well as a weak horizontal streak. Based on the peak density of RGC in the centro-temporal area, anatomical acuity was estimated to be approximately 3 cycles/degree (cpd) in both sexes. However, a behavioural optomotor assay found significantly lower mean acuity in males (0.8 cpd) than females (3.0 cpd), which was not explained by differences in eye size between males and females. An additional behavioural assay, in which we trained individuals to discriminate striped gratings from grey stimuli of the same mean luminance, also showed lower acuity in males (1-2 cpd) than females (2-3 cpd). Thus, although retinal anatomy predicts identical acuity in males and females, two behavioural assays found higher acuity in females than males, a sexual dimorphism which is rare outside of invertebrates. Overall, our results have implications for understanding how Poeciliids perceive visual signals during mate choice and agonistic encounters.
Abstract.
Full text.
Kelley L, Troscianko J (In Press). The evolution of patterning during movement in a large-scale citizen science game.
Proceedings of the Royal Society B: Biological Sciences Full text.
Goumas M, Boogert N, Kelley L (In Press). Urban herring gulls use human behavioural cues to locate food.
Royal Society Open Science Full text.
Goumas M, Lee VE, Boogert NJ, Kelley LA, Thornton A (2020). The Role of Animal Cognition in Human-Wildlife Interactions.
Frontiers in Psychology,
11 Full text.
Goumas M, Burns I, Kelley LA, Boogert NJ (2019). Herring gulls respond to human gaze direction.
Biol Lett,
15(8).
Abstract:
Herring gulls respond to human gaze direction.
Human-wildlife conflict is one of the greatest threats to species populations worldwide. One species facing national declines in the UK is the herring gull (Larus argentatus), despite an increase in numbers in urban areas. Gulls in urban areas are often considered a nuisance owing to behaviours such as food-snatching. Whether urban gull feeding behaviour is influenced by human behavioural cues, such as gaze direction, remains unknown. We therefore measured the approach times of herring gulls to a food source placed in close proximity to an experimenter who either looked directly at the gull or looked away. We found that only 26% of targeted gulls would touch the food, suggesting that food-snatching is likely to be conducted by a minority of individuals. When gulls did touch the food, they took significantly longer to approach when the experimenter's gaze was directed towards them compared with directed away. However, inter-individual behaviour varied greatly, with some gulls approaching similarly quickly in both treatments, while others approached much more slowly when the experimenter was looking at them. These results indicate that reducing human-herring gull conflict may be possible through small changes in human behaviour, but will require consideration of behavioural differences between individual gulls.
Abstract.
Author URL.
Full text.
Kelley LA, Kelley JL (2014). Perceptual biases and animal illusions: a response to comments on Kelley and Kelley. Behavioral Ecology, 25(3), 468-469.
Endler JA, Gaburro J, Kelley LA (2014). Visual effects in great bowerbird sexual displays and their implications for signal design.
Proceedings of the Royal Society B: Biological Sciences,
281(1783), 20140235-20140235.
Abstract:
Visual effects in great bowerbird sexual displays and their implications for signal design
. It is often assumed that the primary purpose of a male's sexual display is to provide information about quality, or to strongly stimulate prospective mates, but other functions of courtship displays have been relatively neglected. Male great bowerbirds (
. Ptilonorhynchus nuchalis
. ) construct bowers that exploit the female's predictable field of view (FOV) during courtship displays by creating forced perspective illusions, and the quality of illusion is a good predictor of mating success. Here, we present and discuss two additional components of male courtship displays that use the female's predetermined viewpoint: (i) the rapid and diverse flashing of coloured objects within her FOV and (ii) chromatic adaptation of the female's eyes that alters her perception of the colour of the displayed objects. Neither is directly related to mating success, but both are likely to increase signal efficacy, and may also be associated with attracting and holding the female's attention. Signal efficacy is constrained by trade-offs between the signal components; there are both positive and negative interactions within multicomponent signals. Important signal components may have a threshold effect on fitness rather than the often assumed linear relationship.
.
Abstract.
Endler JA, Gaburro J, Kelley LA (2014). Visual effects in great bowerbird sexual displays and their implications for signal design (vol 281, 20140235, 2014).
PROCEEDINGS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES,
281(1785).
Author URL.
Kelley LA, Kelley JL (2013). Animal visual illusion and confusion: the importance of a perceptual perspective. Behavioral Ecology, 25(3), 450-463.
Kelley LA, Endler JA (2012). Illusions Promote Mating Success in Great Bowerbirds. Science, 335(6066), 335-338.
Kelley LA, Endler JA (2012). Male great bowerbirds create forced perspective illusions with consistently different individual quality. Proceedings of the National Academy of Sciences, 109(51), 20980-20985.
Endler JA, Mielke PW, Kelley LA (2012). Response to Comment on “Illusions Promote Mating Success in Great Bowerbirds”. Science, 337(6092), 292-292.
Kelley LA, Healy SD (2012). Vocal mimicry in spotted bowerbirds is associated with an alarming context. Journal of Avian Biology, 43(6), 525-530.
Kelley LA, Healy SD (2011). The mimetic repertoire of the spotted bowerbird Ptilonorhynchus maculatus. Naturwissenschaften, 98(6), 501-507.
Kelley LA, Healy SD (2011). Vocal mimicry. Current Biology, 21(1), R9-R10.
Kelley LA, Healy SD (2010). Vocal mimicry in male bowerbirds: who learns from whom?.
Biology Letters,
6(5), 626-629.
Abstract:
Vocal mimicry in male bowerbirds: who learns from whom?
. Vocal mimicry is one of the more striking aspects of avian vocalization and is widespread across songbirds. However, little is known about how mimics acquire heterospecific and environmental sounds. We investigated geographical and individual variation in the mimetic repertoires of males of a proficient mimic, the spotted bowerbird
. Ptilonorhynchus maculatus
. Male bower owners shared more of their mimetic repertoires with neighbouring bower owners than with more distant males. However, interbower distance did not explain variation in the highly repeatable renditions given by bower owners of two commonly mimicked species. From the similarity between model and mimic vocalizations and the patterns of repertoire sharing among males, we suggest that the bowerbirds are learning their mimetic repertoire from heterospecifics and not from each other.
.
Abstract.
Healy SD, Bacon IE, Haggis O, Harris AP, Kelley LA (2009). Explanations for variation in cognitive ability: Behavioural ecology meets comparative cognition. Behavioural Processes, 80(3), 288-294.
Kelley LA, Coe RL, Madden JR, Healy SD (2008). Vocal mimicry in songbirds.
ANIMAL BEHAVIOUR,
76, 521-528.
Author URL.
Publications by year
In Press
Caves E, Troscianko J, Kelley L (In Press). A customizable, low-cost optomotor apparatus: a powerful tool for behaviourally measuring visual capability.
Methods in Ecology and Evolution Full text.
Kelley LA (In Press). California scrub-jays reduce visual cues available to potential pilferers by matching food colour to caching substrate.
Biology Letters Full text.
Galloway J, Green SD, Stevens M, Kelley L (In Press). Finding a signal hidden among noise: how can predators overcome camouflage strategies?.
Philosophical Transactions of the Royal Society B: Biological Sciences Full text.
Goumas M, Kelley L, Boogert N (In Press). Herring gull aversion to gaze in urban and rural human settlements.
Animal Behaviour Full text.
Kelley LA (In Press). How do great bowerbirds construct perspective illusions?.
Royal Society Open Science Full text.
Hughes AE, Griffiths D, Troscianko J, Kelley LA (In Press). No evidence for motion dazzle in an evolutionary citizen science game.
Abstract:
No evidence for motion dazzle in an evolutionary citizen science game
AbstractThe motion dazzle hypothesis posits that high contrast geometric patterns can cause difficulties in tracking a moving target, and has been argued to explain the patterning of animals such as zebras. Research to date has only tested a small number of patterns, offering equivocal support for the hypothesis. Here, we take a genetic programming approach to allow patterns to evolve based on their fitness (time taken to capture) and thus find the optimal strategy for providing protection when moving. Our ‘Dazzle Bug’ citizen science game tested over 1.5 million targets in a touch screen game at a popular visitor attraction. Surprisingly, we found that targets lost pattern elements during evolution and became closely background matching. Modelling results suggested that targets with lower motion energy were harder to catch. Our results indicate that low contrast, featureless targets offer the greatest protection against capture when in motion, challenging the motion dazzle hypothesis.
Abstract.
Kelley L, Caves E (In Press). Sex differences in behavioural and anatomical estimates of visual acuity in the green swordtail Xiphophorus helleri.
Journal of Experimental BiologyAbstract:
Sex differences in behavioural and anatomical estimates of visual acuity in the green swordtail Xiphophorus helleri
Among fishes in the family Poeciliidae, signals such as colour patterns, ornaments, and courtship displays play important roles in mate choice and male-male competition. Despite this, visual capabilities in Poeciliids are understudied, in particular visual acuity, the ability to resolve detail. We used three methods to quantify visual acuity in male and female green swordtails (Xiphophorus helleri), a species in which body size and the length of the male’s extended caudal fin (‘sword’) serve as assessment signals during mate choice and agonistic encounters. Topographic distribution of retinal ganglion cells (RGC) was similar in all individuals and characterized by areas of high cell densities located centro-temporally and nasally, as well as a weak horizontal streak. Based on the peak density of RGC in the centro-temporal area, anatomical acuity was estimated to be approximately 3 cycles/degree (cpd) in both sexes. However, a behavioural optomotor assay found significantly lower mean acuity in males (0.8 cpd) than females (3.0 cpd), which was not explained by differences in eye size between males and females. An additional behavioural assay, in which we trained individuals to discriminate striped gratings from grey stimuli of the same mean luminance, also showed lower acuity in males (1-2 cpd) than females (2-3 cpd). Thus, although retinal anatomy predicts identical acuity in males and females, two behavioural assays found higher acuity in females than males, a sexual dimorphism which is rare outside of invertebrates. Overall, our results have implications for understanding how Poeciliids perceive visual signals during mate choice and agonistic encounters.
Abstract.
Full text.
Kelley L, Troscianko J (In Press). The evolution of patterning during movement in a large-scale citizen science game.
Proceedings of the Royal Society B: Biological Sciences Full text.
Goumas M, Boogert N, Kelley L (In Press). Urban herring gulls use human behavioural cues to locate food.
Royal Society Open Science Full text.
2021
Henderson JM (2021). The Role of Edge Enhancement in Animal Colouration.
Abstract:
The Role of Edge Enhancement in Animal Colouration
Many animals exhibit contrasting shapes across their surface which are thought to help conceal them from potential predators. It has been suggested that these patterns, known as disruptive markings, function by creating false edges that break up the characteristic form of the animal. Some disruptive patterns are graded in tone so that light patches become lighter and dark patches become darker at the points where they converge. Whilst this type of edge enhancement has been shown to improve camouflage efficacy, it still remains unclear how these patterns are typically expressed within real animals and how they may function within a natural setting. In chapter 1, the strength of edge enhancement was quantified for a variety of British moth species through the use of calibrated digital photography. Across the different species, the level of edge enhancement was shown to be more pronounced near the outline of the moth compared to the centre of the wing, caused by a greater offset in the dark edge. In chapter 2, the effect of edge enhancement on camouflage was tested within a natural setting against both avian and human observers. Whilst edge enhancement had no effect on the survival of targets against avian predators, it did affect detection by humans. However, this effect was dependent upon the arrangement of pattern features, with edge enhancement reducing detection when intersecting the outline of the target but increasing detection when expressed only on internal-based markings. Regardless of pattern placement, edge enhanced targets were detected from greater distances. When combined, the results from Chapter 1 and 2 suggest the efficacy of enhanced edges is greatly influenced by their arrangement within a pattern and that they provide camouflage through some function of edge disruption.
Abstract.
Full text.
2020
Goumas M, Lee VE, Boogert NJ, Kelley LA, Thornton A (2020). The Role of Animal Cognition in Human-Wildlife Interactions.
Frontiers in Psychology,
11 Full text.
2019
Goumas M, Burns I, Kelley LA, Boogert NJ (2019). Herring gulls respond to human gaze direction.
Biol Lett,
15(8).
Abstract:
Herring gulls respond to human gaze direction.
Human-wildlife conflict is one of the greatest threats to species populations worldwide. One species facing national declines in the UK is the herring gull (Larus argentatus), despite an increase in numbers in urban areas. Gulls in urban areas are often considered a nuisance owing to behaviours such as food-snatching. Whether urban gull feeding behaviour is influenced by human behavioural cues, such as gaze direction, remains unknown. We therefore measured the approach times of herring gulls to a food source placed in close proximity to an experimenter who either looked directly at the gull or looked away. We found that only 26% of targeted gulls would touch the food, suggesting that food-snatching is likely to be conducted by a minority of individuals. When gulls did touch the food, they took significantly longer to approach when the experimenter's gaze was directed towards them compared with directed away. However, inter-individual behaviour varied greatly, with some gulls approaching similarly quickly in both treatments, while others approached much more slowly when the experimenter was looking at them. These results indicate that reducing human-herring gull conflict may be possible through small changes in human behaviour, but will require consideration of behavioural differences between individual gulls.
Abstract.
Author URL.
Full text.
2014
Kelley LA, Kelley JL (2014). Perceptual biases and animal illusions: a response to comments on Kelley and Kelley. Behavioral Ecology, 25(3), 468-469.
Endler JA, Gaburro J, Kelley LA (2014). Visual effects in great bowerbird sexual displays and their implications for signal design.
Proceedings of the Royal Society B: Biological Sciences,
281(1783), 20140235-20140235.
Abstract:
Visual effects in great bowerbird sexual displays and their implications for signal design
. It is often assumed that the primary purpose of a male's sexual display is to provide information about quality, or to strongly stimulate prospective mates, but other functions of courtship displays have been relatively neglected. Male great bowerbirds (
. Ptilonorhynchus nuchalis
. ) construct bowers that exploit the female's predictable field of view (FOV) during courtship displays by creating forced perspective illusions, and the quality of illusion is a good predictor of mating success. Here, we present and discuss two additional components of male courtship displays that use the female's predetermined viewpoint: (i) the rapid and diverse flashing of coloured objects within her FOV and (ii) chromatic adaptation of the female's eyes that alters her perception of the colour of the displayed objects. Neither is directly related to mating success, but both are likely to increase signal efficacy, and may also be associated with attracting and holding the female's attention. Signal efficacy is constrained by trade-offs between the signal components; there are both positive and negative interactions within multicomponent signals. Important signal components may have a threshold effect on fitness rather than the often assumed linear relationship.
.
Abstract.
Endler JA, Gaburro J, Kelley LA (2014). Visual effects in great bowerbird sexual displays and their implications for signal design (vol 281, 20140235, 2014).
PROCEEDINGS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES,
281(1785).
Author URL.
2013
Kelley LA, Kelley JL (2013). Animal visual illusion and confusion: the importance of a perceptual perspective. Behavioral Ecology, 25(3), 450-463.
2012
Kelley LA, Endler JA (2012). Illusions Promote Mating Success in Great Bowerbirds. Science, 335(6066), 335-338.
Kelley LA, Endler JA (2012). Male great bowerbirds create forced perspective illusions with consistently different individual quality. Proceedings of the National Academy of Sciences, 109(51), 20980-20985.
Endler JA, Mielke PW, Kelley LA (2012). Response to Comment on “Illusions Promote Mating Success in Great Bowerbirds”. Science, 337(6092), 292-292.
Kelley LA, Healy SD (2012). Vocal mimicry in spotted bowerbirds is associated with an alarming context. Journal of Avian Biology, 43(6), 525-530.
2011
Kelley LA, Healy SD (2011). The mimetic repertoire of the spotted bowerbird Ptilonorhynchus maculatus. Naturwissenschaften, 98(6), 501-507.
Kelley LA, Healy SD (2011). Vocal mimicry. Current Biology, 21(1), R9-R10.
2010
Kelley LA, Healy SD (2010). Vocal mimicry in male bowerbirds: who learns from whom?.
Biology Letters,
6(5), 626-629.
Abstract:
Vocal mimicry in male bowerbirds: who learns from whom?
. Vocal mimicry is one of the more striking aspects of avian vocalization and is widespread across songbirds. However, little is known about how mimics acquire heterospecific and environmental sounds. We investigated geographical and individual variation in the mimetic repertoires of males of a proficient mimic, the spotted bowerbird
. Ptilonorhynchus maculatus
. Male bower owners shared more of their mimetic repertoires with neighbouring bower owners than with more distant males. However, interbower distance did not explain variation in the highly repeatable renditions given by bower owners of two commonly mimicked species. From the similarity between model and mimic vocalizations and the patterns of repertoire sharing among males, we suggest that the bowerbirds are learning their mimetic repertoire from heterospecifics and not from each other.
.
Abstract.
2009
Healy SD, Bacon IE, Haggis O, Harris AP, Kelley LA (2009). Explanations for variation in cognitive ability: Behavioural ecology meets comparative cognition. Behavioural Processes, 80(3), 288-294.
2008
Kelley LA, Coe RL, Madden JR, Healy SD (2008). Vocal mimicry in songbirds.
ANIMAL BEHAVIOUR,
76, 521-528.
Author URL.
