IBRG hosts informal meetings
where members of affiliated lab groups in Princeton University's
Department of Ecology and
Evolutionary Biology give presentations on their current research.
These talks are usually about 20-30 minutes long followed by
30 minutes of discussion. We meet during the academic year on
Fridays from 3-4pm in Guyot 100.
All are welcome to attend!
The speaker schedule and mailing list for the 2022-23
academic year are being maintained by
Josh LaPergola, Bre Bennett, and David Ocampo.
Please contact any of us if you are interested in presenting your research or would like to add
your name to the group's mailing list.
Title: Socioecological drivers of complex social structure in an avian cooperative breeder
Cooperatively breeding societies, in which one or more non-parental individuals (“alloparents”) care for young alongside the parents, show considerable variation in social structure. Traditionally, such societies have been thought to comprise small, kin-based family groups where offspring from previous broods delay dispersal and help raise closely-related offspring to gain indirect fitness benefits when independent breeding opportunities are unavailable or yield lower fitness outcomes. However, genetic evidence is increasingly revealing cooperatively breeding species whose social groups comprise unrelated individuals as co-breeders or alloparents or both (e.g., 45% of all avian cooperative breeders). Such social groups exhibit complexity in social structure such as large group size, multiple breeders, and low and varied group kin structure. To understand why such complex societies form and how are they maintained when the opportunity to gain indirect benefits via kin selection is low and variable, I investigated the direct and indirect benefits driving a key demographic process, dispersal, and the resulting variation in group social structure on the individual, group, and population levels in an obligate, avian cooperative breeder, the superb starling (Lamprotornis superbus). Found on the East African savanna, superb starlings live in social groups year-round that comprise both residents, who are born in the group and forego dispersal, and immigrants from other social groups. Groups have multiple breeding pairs (as well as non-breeding alloparents), and both resident and immigrant males can breed by forming pair bonds with immigrant females. I used a combination of long-term, individual-level data spanning 15 years from nine groups monitored at the Mpala Research Centre in Kenya and fine-scale genetic and environmental data sampled across 22 social groups that included the long-term study population. I will present three key findings that underscore the importance of direct benefits in the formation and maintenance of cooperative social groups with complex social structure in a harsh and unpredictable environment.
Title: In sickness and in health? Black Vultures at the nexus of parental care, disease, and sociality
Group living in social animals comes with a suite of costs and benefits. Benefits like vigilance against predators, access to social information, and higher foraging success may help maintain sociality, but may come at the cost of increased intraspecific competition for resources and higher risk of disease transmission through close coalitions. Black Vultures (Coragyps atratus) live in mixed kin and non-kin, roosting and foraging groups, but breed in seclusion until young reach fledging age and join parents at the communal roosts. While vultures are assumed to have robust immune systems because of their carrion diets, observations during the recent outbreak of highly pathogenic avian influenza (HPAI) suggest black vultures are indeed vulnerable to infection by some pathogens. I will investigate this outbreak’s impact on the population of black vultures in southeastern Pennsylvania by monitoring their breeding behavior, nesting success, and eventual offspring recruitment into communal roosts.
Title: Vignettes of natural history: the importance of preparation, distractibility, and opportunity in fieldwork and why we need more natural history
Natural history, what some have defined as "where organisms are and what they do in their environments, including interactions with other organisms,"* provides the foundation for most of biology. Indeed if not for the meanderings and observations of curious naturalists, entire fields of biological inquiry would not exist. In today's IBRG, we hope to stimulate a productive discussion about the role of natural history in our own research efforts, and why we view enhanced and sustained support for natural history research as critical to the growth and success of the fields of ecology, evolution, and behavior. From PCR to poisonous birds, the world around us is rife with the possibility of discovery. What can we all do to promote, support, and encourage the preparation, distractibility, and opportunity necessary for making these discoveries? Please come ready to discuss.
*Greene, Harry W., and Jonathan B. Losos. "Systematics, natural history, and conservation: field biologists must fight a public-image problem." BioScience (1988): 458-462.
Title: Applying animal behavior to promote good ecotourism practices
Being amid nature is fun and soothing. To be frank, it is probably what turned us into animal behaviorists and ecologists in the first place. That is not all. Ecotourism is a key element to create connection with nature, and therefore willingness to preserve it, and is a promising way to generate revenue without environmental harm, especially in developing countries. Despite that, tourism in natural areas has reached mass consumption and exposes natural areas to humans in such a way that it may be causing harm to the very environment it depends upon. Over the last few years, my research group has used fish and divers to develop a framework on how mass ecotourism may affect animals at different levels, from physiology and behavior to ecology. Now, we are working on how each aspect of ecotourism (the proximity to animals, the noise we make, the chemicals we leave behind, and how we behave) affect animals. We hope this will allow us to design ideal ecotourism benchmarks and help to promote its full sustainability potential by reducing its impacts.
Title: Consequences of Environmental Stress on Social Behavior
One of the consequences of global climate change is unpredictable precipitation patterns and extended periods of drought. In response to these shifting environmental conditions and the stressors that accompany them, animals are faced with the challenge of modifying their behavior to adapt to the changing climate. In response to these shifting environmental conditions and the stressors that come along with them, animals are increasingly faced with the challenge of modifying their behavior to adapt to the changing climate. Behavioral flexibility in how animals allocate their time budgets may be one of the ways in which they respond to changes in their immediate needs. In particular, as environmental stresses become more acute, animals may prioritize acquiring these resources at the expense of less necessary behaviors to immediate fitness, such as socializing. Laikipia county in central Kenya has been experiencing a severe drought since 2020. Plains zebras (Equus quagga), a highly social equid that lives in stable harems, are known to be susceptible to droughts, though less so than other ungulates due to their physiology as hind gut fermenters which allows them to eat high quantities of low quality forage. Using the data we collected between 2021 and 2022, during which time the drought intensified, we seek to address the following questions: 1) How do zebras change their social behavior in times of environmental stress? 2) What parts of their communicative repertoires are unused/modified during these periods, and what parts are the “core” or essential elements of communication that are preserved even in times of environmental stress?
Title: Workload inequality increases with group size in a cooperatively breeding bird
Groups of animals often cooperate on shared tasks, but individual contributions are not necessarily equal: individuals can specialize on different tasks (division of labor) or vary in total work performed. Either of these patterns can have fitness consequences. However, few studies have examined division of labor and workload inequality in vertebrates. We analyzed individual contributions to parental care in the greater ani (Crotophaga major), a bird that nests communally in groups of two or three pairs and up to two non-breeding helpers. We examined nearly 600 hours of video footage of 10 groups to quantify individual contributions to nest building, incubation, brooding, and nestling feeding. There was no clear evidence of division of labor; rather, contributions across behaviors tended to be positively correlated, suggesting individual differences in overall work performed. Indeed, one of the breeding pairs in three-pair groups and helpers contributed significantly less than the other two pairs. Inequality in overall workload, as measured by the Gini coefficient, was significantly higher in three-pair groups than two-pair groups, as predicted by collective action theory. Finally, anecdotal observations suggested that behavioral conflict was more frequent in three-pair groups, with aggression typically directed at the pair that contributed the least to parental care. Taken together, these patterns may reflect conflicts of interest over group size and group membership, in which some group members attempt to limit others’ access to the nest.
Title: Context-dependence in the relationship between colony size and fitness: disentangling drivers of group-living in one of the few colonially nesting woodpeckers
Determining why some species live in groups while others do not remains a challenge because there are many automatic costs of group-living but no automatic benefits. To tackle this paradox, researchers typically combine analyzing the relationship between group size and fitness with detailed behavioral observations to test two non-mutually exclusive alternative hypotheses for why animals live in groups: (1) socially-derived benefits and (2) spatial clustering of key resources. A key distinguishing prediction between these two hypotheses is the relationship between group size and fitness, which would be positive under social benefits but flat (or negative) under resource clustering. Yet ecological context can influence the shape of the group-size-fitness relationship. To explore the relationship between ecological context and the group-size-fitness relationship, I studied the Hispaniolan Woodpecker (Melanerpes striatus), a facultative colonial breeder, over six breeding seasons in the Dominican Republic. No measure of reproductive success, including annual reproductive success, was significantly associated with colony size itself. However, Hispaniolan Woodpeckers nested almost exclusively in Roystonea palms. Although these palms were not themselves rare, dead palms were, and colonies were larger in dead palms than in live ones. In contrast to live palms, dead palms allowed faster cavity excavation, more available old cavities, and protection from a major cause of nest failure in live palms: cavity flooding. When accounting for palm status (live vs. dead), the relationship between nesting success (fledging one or more chicks) and colony size was context-dependent: weakly positive in dead trees but negative in live trees. Colonial nesting in the Hispaniolan Woodpecker does not appear to yield social benefits for reproductive success. Instead, coloniality is more likely driven by limited availability of dead trees, old cavities, and avoiding a major environmental cause of nest failure.
Title: Parasitic nestling rejection by a Shiny Cowbird (Molothrus bonariensis) host
Brood parasitic birds impose severe reproductive costs on their hosts and these costs thus strongly select for anti-parasitic defenses. While many hosts show efficient parasitic egg rejection, the lack of nestling rejection, even when the parasitic chick is an obvious aberration, is rare and has been less studied. The evolution of nestling rejection may be constrained by finely tuned egg rejection mechanisms, making parasitic nestlings too rare to elicit strong selection pressure or by the risk of misimprinting on a parasitic chick in the first breeding attempt and thus rejecting future own offspring. Therefore, nestling rejection should be most common in host species that are egg acceptors, with high incidence and costs of parasitism, and low cost of recognition errors through misimprinting. Firewood-gatherer (Anumbius annumbi) is an infrequent Shiny Cowbird (Molothrus bonariensis) host and has been proposed as a potential rejecter of parasite chicks, since 6 cowbird chicks have been found dead in nests of the species. However, whether chick mortality is due to chick rejection or other causes is not yet known. We carried out a field experiment seeking to address the following questions: 1) What is the Firewood-gatherer's cost of being parasitized by the Shiny Cowbird? 2) Does the Firewood-gatherer reject brood parasitic eggs or nestlings? 3) What mechanism does the Firewood-gatherer use?
Title: Behavioral Ecology of a neotropical montane finch: Advances and Questions to be resolved
The behavioral ecology of certain Neotropical birds is less understood than that of their temperate counterparts, partially due to a lack of long-term study systems. In this talk, I will summarize the results of five years of studies on a population of the Grey-browed Brushfinch (Arremon assimilis) in the Eastern Andes of Colombia. Like closely related species, pairs in this population are highly territorial. Initially, I was interested in studying the dynamics of annual territorial defense and how this affects the song repertoire and male interactions. I found that neighboring males share a greater number of songs compared to more distant males. Since repertoire sharing may mediate male-male interactions, we hypothesized that males would be more aggressive to strangers compared to neighbors. However, males showed the opposite trend, known as the 'nasty neighbor effect'. Additionally, I wanted to test whether competition between males could be a precursor to the evolution of plumage patches. Patches, such as the presence or absence of a black pectoral band, have been hypothesized to act as honest signals in this genus. However, in territorial intrusion experiments, males of A. basilicus (banded) and A. assimilis (unbanded) showed equal aggression towards banded and unbanded taxidermy mounts. Similarly, males of A. assimilis painted with a pectoral band did not show any changes in physical condition, corticosterone levels, or home range size compared to untreated males without a band. However, painted males did suffer divorces, suggesting a possible role of female preferences in the phenotypic divergence between Arremon populations.
Sofía Ten* (University of Valencia (Spain) and VSRC in Dobson Lab)
Title: Epibiotic fauna as indicators of their cetacean and sea turtle hosts
The external surface of cetaceans and sea turtles are biodiverse ecosystems. Despite being often despised or overlooked, many of these epibionts are suitable bio-indicators of their basibionts (i.e., cetaceans and sea turtles), informing on, e.g., population structure, hydrodynamics or phylogeography. The present talk will provide insight on the use of epibiotic barnacles as indicators of habitat use at a regional and global scale for sea turtles and whales, respectively. Sea turtles exploit a variety of habitats during their lifetime and are thus exposed to several threats, including fisheries interaction. Mitigating this impact requires determining patterns of habitat use. We investigated the use of epibiotic barnacles as a cost-effective method to ascertain habitat use by Mediterranean loggerhead sea turtles (Caretta caretta). Barnacle community, which differed between turtles captured by oceanic or neritic fisheries, and age not only shed light on the habitat where turtles died, but also helped to trace movements and residence times in each habitat. Antarctic minke whales (Balaenoptera bonaerensis) breed in tropical and temperate waters of the Southern Hemisphere in winter and feed in Antarctic grounds in the austral summer. These seasonal pattern could be less defined than for other whales, but evidence is scanty. We describe the epibiotic fauna of Antarctic minke whales and explore its potential to trace migrations. All specimens of their epibiotic barnacle Xenobalanus globicipitis were dead and a geographic analysis indicated a marked drop of occurrence where minimum sea surface temperature <12 °C. Thus, its field detection on whales in polar waters could evince seasonal migration from warmer regions.
