Improvement of individual camouflage through background choice in ground-nesting birds.

Animal camouflage is a longstanding example of adaptation. Much research has tested how camouflage prevents detection and recognition, largely focusing on changes to an animal's own appearance over evolution. However, animals could also substantially alter their camouflage by behaviourally choosing appropriate substrates. Recent studies suggest that individuals from several animal taxa could select backgrounds or positions to improve concealment. Here, we test whether individual wild animals choose backgrounds in complex environments, and whether this improves camouflage against predator vision. We studied nest site selection by nine species of ground-nesting birds (nightjars, plovers and coursers) in Zambia, and used image analysis and vision modeling to quantify egg and plumage camouflage to predator vision. Individual birds chose backgrounds that enhanced their camouflage, being better matched to their chosen backgrounds than to other potential backgrounds with respect to multiple aspects of camouflage. This occurred at all three spatial scales tested (a few cm and five meters from the nest, and compared to other sites chosen by conspecifics), and was the case for the eggs of all bird groups studied, and for adult nightjar plumage. Thus, individual wild animals improve their camouflage through active background choice, with choices highly refined across multiple spatial scales

Escape Distance in Ground-Nesting Birds Differs with Individual Level of Camouflage.

Camouflage is one of the most widespread antipredator strategies in the animal kingdom, yet no animal can match its background perfectly in a complex environment. Therefore, selection should favor individuals that use information on how effective their camouflage is in their immediate habitat when responding to an approaching threat. In a field study of African ground-nesting birds (plovers, coursers, and nightjars), we tested the hypothesis that individuals adaptively modulate their escape behavior in relation to their degree of background matching. We used digital imaging and models of predator vision to quantify differences in color, luminance, and pattern between eggs and their background, as well as the plumage of incubating adult nightjars. We found that plovers and coursers showed greater escape distances when their eggs were a poorer pattern match to the background. Nightjars sit on their eggs until a potential threat is nearby, and, correspondingly, they showed greater escape distances when the pattern and color match of the incubating adult's plumage-rather than its eggs-was a poorer match to the background. Finally, escape distances were shorter in the middle of the day, suggesting that escape behavior is mediated by both camouflage and thermoregulation.In Zambia we thank the Bruce-Miller, Duckett and Nicolle families, Collins Moya and numerous other nest-finding assistants and land-owners, Lackson Chama, and the Zambia Wildlife Authority. We also thank Tony Fulford and are grateful for the helpful comments provided by Tim Caro, Innes Cuthill, Daniel Osorio, and two anonymous referees. J.T., J.W-A. and M.S. were funded by a Biotechnology and Biological Sciences Research Council (BBSRC) grant BB/J018309/1 to M.S., and a BBSRC David Phillips Research Fellowship (BB/G022887/1) to M.S., and C.N.S was funded by a Royal Society Dorothy Hodgkin Fellowship, a BBSRC David Phillips Fellowship (BB/J014109/1) and the DST-NRF Centre of Excellence at the Percy FitzPatrick Institute.This is the author accepted manuscript. It is currently under an indefinite embargo pending publication by University of Chicago Press

Spatial behavior of domestic cats and the effects of outdoor access restrictions and interventions to reduce predation of wildlife

Domestic cats (Felis catus) that roam outdoors have increased exposure to hazards to their health and welfare. Outdoor cats can themselves present a hazard to biodiversity conservation and wild animal welfare. Approaches to reducing predation of wildlife by cats might also bring benefits to cats by reducing their roaming and associated risks. We investigated ranging behaviors of domestic cats that regularly captured wild prey, and that had restricted or unrestricted outdoor access. We tested whether interventions aimed at reducing predation also affected their spatial behavior. We evaluated cat bells, Birdsbesafe collar covers, using a “puzzle feeder”, provision of meat-rich food, object play, and a control group. Seventy-two cats in 48 households in England completed the 12-week trial in spring 2019. Home ranges were small (median AKDE95 = 1.51 ha). Cats with unrestricted outdoor access had 75% larger home ranges, 31% greater daily distances traveled, and reached 46% greater maximum distances from home, than cats with restricted outdoor access. None of the treatments intended to reduce predation affected cat ranges or distances traveled. While owners might use interventions to reduce predation, the only effective means of reducing cat roaming and associated exposure to outdoor hazards was restriction of outdoor access

Spatial and temporal variation in proximity networks of commercial dairy cattle in Great Britain

The nature of contacts between hosts can be important in facilitating or impeding the spread of pathogens within a population. Networks constructed from contacts between hosts allow examination of how individual variation might influence the spread of infections. Studying the contact networks of livestock species managed under different conditions can additionally provide insight into their influence on these contact structures. We collected high-resolution proximity and GPS location data from nine groups of domestic cattle (mean group size = 85) in seven dairy herds employing a range of grazing and housing regimes. Networks were constructed from cattle contacts (defined by proximity) aggregated by different temporal windows (2 h, 24 h, and approximately 1 week) and by location within the farm. Networks of contacts aggregated over the whole study were highly saturated but dividing contacts by space and time revealed substantial variation in cattle interactions. Cows showed statistically significant variation in the frequency of their contacts and in the number of cows with which they were in contact. When cows were in buildings, compared to being on pasture, contact durations were longer and cows contacted more other cows. A small number of cows showed evidence of consistent relationships but the majority of cattle did not. In one group where management allowed free access to all farm areas, cows showed asynchronous space use and, while at pasture, contacted fewer other cows and showed substantially greater between-individual variation in contacts than other groups. We highlight the degree to which variations in management (e.g. grazing access, milking routine) substantially alter cattle contact patterns, with potentially major implications for infection transmission and social interactions. In particular, where individual cows have free choice of their environment, the resulting contact networks may have a less-risky structure that could reduce the likelihood of direct transmission of infections

Quantifying direct and indirect contacts for the potential transmission of infection between species using a multilayer contact network

Detecting opportunities for between-species transmission of pathogens can be challenging, particularly if rare behaviours or environmental transmission are involved. We present a multilayer network framework to quantify transmission potential in multi-host systems, incorporating environmental transmission, by using empirical data on direct and indirect contacts between European badgers Meles meles and domestic cattle. We identify that indirect contacts via the environment at badger latrines on pasture are likely to be important for transmission within badger populations and between badgers and cattle. We also find a positive correlation between the role of individual badgers within the badger social network, and their role in the overall badger-cattle-environment network, suggesting that the same behavioural traits contribute to the role of individual badgers in within- and between-species transmission. These findings have implications for disease management interventions in this system, and our novel network approach can provide general insights into transmission in other multi-host disease systems

Data from: Escape distance in ground-nesting birds differs with individual level of camouflage

Camouflage is one of the most widespread antipredator strategies in the animal kingdom, yet no animal can match its background perfectly in a complex environment. Therefore, selection should favor individuals that use information on how effective their camouflage is in their immediate habitat when responding to an approaching threat. In a field study of African ground-nesting birds (plovers, coursers, and nightjars), we tested the hypothesis that individuals adaptively modulate their escape behavior in relation to their degree of background matching. We used digital imaging and models of predator vision to quantify differences in color, luminance, and pattern between eggs and their background, as well as the plumage of incubating adult nightjars. We found that plovers and coursers showed greater escape distances when their eggs were a poorer pattern match to the background. Nightjars sit on their eggs until a potential threat is nearby, and, correspondingly, they showed greater escape distances when the pattern and color match of the incubating adult's plumage-rather than its eggs-was a poorer match to the background. Finally, escape distances were shorter in the middle of the day, suggesting that escape behavior is mediated by both camouflage and thermoregulation

56812 (Wilson-Aggarwal et al)

Data for ground nesting birds in Zambia (nightjars, plovers and coursers), collected in the field. The data Includes species, nest code, escape distances, visit number, decimal hour (time of day), clutch size, mean egg volume and camouflage metrics. The document includes separate tabs for plover and courser egg camouflage, nightjar egg camouflage and nightjar adult camouflage. In addition there are tabs for the different predator visual systems

Nest covering in plovers: how modifying the visual environment influences egg camouflage (dataset)

Data from our study of nest covering in Kittlitz's ploversThe article related to this dataset is available at http://hdl.handle.net/10871/23246.Data from our study of Kittlitz's plover nest covering behaviour.Biotechnology and Biological Sciences Research Council, Royal Society, DST-NRF Centre of Excellence at the FitzPatrick Institut

Data from: Relative advantages of dichromatic and trichromatic color vision in camouflage breaking

There is huge diversity in visual systems and color discrimination abilities, thought to stem from an animal’s ecology and life history. Many primate species maintain a polymorphism in color vision, whereby most individuals are dichromats but some females are trichromats, implying that selection sometimes favors dichromatic vision. Detecting camouflaged prey is thought to be a task where dichromatic individuals could have an advantage. However, previous work either has not been able to disentangle camouflage detection from other ecological or social explanations, or did not use biologically relevant cryptic stimuli to test this hypothesis under controlled conditions. Here, we used online “citizen science” games to test how quickly humans could detect cryptic birds (incubating nightjars) and eggs (of nightjars, plovers and coursers) under trichromatic and simulated dichromatic viewing conditions. Trichromats had an overall advantage, although there were significant differences in performance between viewing conditions. When searching for consistently shaped and patterned adult nightjars, simulated dichromats were more heavily influenced by the degree of pattern difference than were trichromats, and were poorer at detecting prey with inferior pattern and luminance camouflage. When searching for clutches of eggs—which were more variable in appearance and shape than the adult nightjars—the simulated dichromats learnt to detect the clutches faster, but were less sensitive to subtle luminance differences. These results suggest there are substantial differences in the cues available under viewing conditions that simulate different receptor types, and that these interact with the scene in complex ways to affect camouflage breaking