Biology subjects

Healy, S. D.

Publications and source records attributed to Healy, S. D..

5 recordsLinked to original sources

bioRxiv2025

Dynamic strategic social learning in nest-building zebra finches and its generalisability

Animals often balance asocial and social information strategically, adjusting when and from whom they copy based on context. Yet the cognition driving this dynamic--and its broader implications--remains poorly understood. We tested whether zebra finches use a copy-if-dissatisfied strategy by manipulating the quality of their initial nest-building or reproductive experience, showing them a conspecific nest-builder, and tracking subsequent material choices. Builder-males were more likely to choose the demon-strated social material--particularly at first choice--if they had previously used low-quality material. Using cognitive modelling, we estimated how latent learning mechanisms shaped decisions, identifying two asocial and two social parameters. These estimates provide the first formal evidence for the cognitive basis of nest building. Forward simulations informed--but not predetermined--by these parameters approximated observed behaviour, supporting their causal role. We then used these parameters in exploratory simulations to test how choices might shift under novel payoff contexts. We found that payoff structure--not (dis)satisfaction--was the primary driver of social material use, though higher rewards did not proportionally increase copying. These exploratory simulation results offer preliminary insight into mechanisms underlying material-use variation. Our study illustrates how computational modelling can robustly link behaviour to underlying learning mechanisms and probe the generalisability of animal cognition--a rarity in this field.

animal behavior and cognition↗

bioRxiv2023

Anthropogenic nest material use correlates with human landscape modifications in a global sample of birds

As humans increasingly modify the natural world, many animals have responded by changing their behaviour. Predicting the extent of these responses is a key step in conserving these species. For example, the tendency for some species of birds to incorporate anthropogenic items - particularly plastic material - into their nests is of increasing concern, as in some cases this behaviour has harmful effects on both adults and young. Studies of this phenomenon, however, have to date been limited in geographic and taxonomic scope. To investigate the global correlates of anthropogenic (including plastic) nest material use, we used Bayesian phylogenetic mixed models and a dataset of recorded nest materials in 6,147 species of birds. We find that after controlling for research effort, anthropogenic nest material use is correlated with proximity to human landscape modification, synanthropic (artificial) nesting locations, breeding environment, and the number of materials that has been recorded within the species nest. We also demonstrate that anthropogenic nest material use is unrelated to body mass, range size, or conservation status. These results indicate that anthropogenic materials are more likely to be included in nests when they are more readily available, as well as potentially by species who have more flexibility in nest material choice.

evolutionary biology↗

bioRxiv2023

Nest traits for the world's birds

MotivationA well-constructed nest is a key element of successful reproduction in most species of birds, and nest-building strategies vary widely across the class. Macroecological and macroevolutionary studies tend to group nest design into a small number of discrete categories, often based on taxonomic inference. In reality, however, many species display considerable intraspecific variation in their nest-building behaviour, and broad-level categories may include many functionally distinct nest types. To address this confusion in the literature and facilitate future studies of broad-scale variation in avian parental care, we here introduce a detailed, global comparative database of nest building in birds, together with preliminary correlations between these traits and species-level environmental variables. Main types of variable containedWe present species-level data for nest structure, location, height, material composition, sex of builder, building time, and nest dimensions. Spatial location and grainGlobal. Maps are presented at the 1{degrees}x1{degrees} level. Time period and grainIncluded species are generally extant, although we present some data for recently extinct taxa. The data was collected 2017-2021 and was drawn from secondary sources published 1992-2021. Major taxa and level of measurementPartial or complete trait data is presented for 8,601 species of birds, representing 36 of 36 orders and 239 of 243 families. Software formatData have been uploaded as Supplementary Material in .xlsx format and are separated by species and source for all traits (S1) as well as summarised at the species level for structure and location variables (S2).

evolutionary biology↗

bioRxiv2022

3D flightpaths reveal the development of spatial memory in wild hummingbirds

Many animals learn to relocate important places and reflect this spatial knowledge in their behaviour. Traditionally evidence for learning is examined experimentally by studying spatial memory. However, tools developed for analysing tracking data from widely ranging animals allow a more holistic analysis of behaviour. Here we use the two together in novel combination of experimental and modelling approaches to analyse how patterns of hummingbird movements change as birds learn to find a reward in a location indicated by a pair of landmarks. Using hidden Markov models (HMMs) we identified two movement states which we interpret as Search and Travel and compared these to experimental behavioural measures of spatial memory. When birds had a single training trial to learn a flowers location, both the behavioural measures and HMMs showed that hummingbirds relied on landmarks to guide search. Hummingbirds focussed hovering around the rewarded location and were more likely to be in the Search state, and more likely to switch from Travel to Search, when closer to the rewarded location, but only when the landmarks were present. When birds had had 12 additional training trials, however, the HMMs and behavioural measures showed differences in how reliant birds were on landmarks. While behaviours like hovering were still strongly affected by removing landmarks, the likelihood of being in or entered the Search state was the same regardless of whether the landmarks were present or removed. These results suggests that hummingbirds rapidly learn to use nearby landmarks to structure where they search, but as birds gain experience the role of these landmarks changes. While familiar local landmarks were still essential for precise search, experienced birds were able to use alternative cues to guide broad-scale transitions between behaviour. HMMs and traditional behavioural measures each capture a different aspect of this learning, with neither approach alone accurately described the role of landmarks in spatial learning.

animal behavior and cognition↗

bioRxiv2019

Ecology, phylogeny, and the evolution of developmental duration in birds

The duration of the developmental period represents a fundamental axis of life history variation in animals, yet broad insights regarding the drivers of this diversity are currently lacking. Here using embryological data combined with information on incubation and fledging periods for 3096 species, we test key mechanistic and adaptive explanations for the evolutionary diversification of developmental durations in birds. First, using data on embryonic development for 20 model species, we show that developmental phases associated primarily with growth are longer and more variable than earlier phases, consistent with a role for allometric constraint in determining the duration of development. Second, using phylogenetic comparative methods, we find that avian developmental durations retain a strong imprint of deep evolutionary history, and that after accounting for these effects, body size differences among species explain less variation (5-22%) in developmental period lengths than previously thought. Finally, by collecting data for a suite of potential explanatory variables, our analyses reveal broad-scale ecological correlates of developmental durations, including variables associated with the relative safety of the developmental environment (e.g. nest height, insularity) and pressures of breeding phenology (e.g. migration). Overall, our results reveal that the combined effects of species body size, ecology, and phylogenetic history can account for 62-93% of the variation in developmental durations across birds, providing broad-scale quantitative insight into the relative importance of mechanistic constraints, adaptive evolution and evolutionary constraints in shaping the diversification of this key life-history trait.

evolutionary biology↗