Cynthia Ursino · Behavioral Ecology

Welcome!

I study the ecology and evolution of bird behavior, with a particular focus on mating systems, brood parasitism, ecto-parasitism, cooperative behavior, and parental care.
The aim is to understand how these systems evolve in response to ecological and evolutionary pressures. I combine behavioral observations, genetic analysis, and field experiments, with fieldwork conducted in Argentina and lab work in the US. Currently, I investigate the dynamics of species with and without parental care, exploring how reproductive strategies such as cooperative breeding and brood parasitism influence social and genetic mating behaviors
Bird chicks on a nest, just born, without feathers and with their eyes closed
A group of three Firewok-gatherers standing on the top of a tree. Part of their body is covered by the leafs and branches
Cynthia Ursino and a fellow researcher working on a mist-net for safe capturing birds, for research purposes
Adult Baywing bird perched on a tree
Panoramic image of a grassland with only one tree standing on the middle of the field. There are two mist-nets opened, waiting to catch the studied birds
Cynthia Ursino in the lab analyzing some samples from her reasearch campaign
Three birds just hatched from their eggs

Publications

Google Scholar | * denotes corresponding author | Equal contribution

If you do not have access to any of these articles and would like a copy, please feel free to email me at cursino@princeton.edu

Realistic illustration of an adult Starling feeding his three chicks on the nest (hole in a tree). On the side there are Philornis flies, a parasitic species that lay their eggs on the skin of birds
19. Ursino, C.A.*; Palacios, M.G.; Ibañez, L.M. & Fiorini, V.D. (2024)

Enemy of the invader: impact of the native ectoparasite Philornis spp. on an invasive bird species, the European starling (Sturnus vulgaris)

Biological Invasions, 26(5): 1413–1424
DOI: 10.1007/s10530-024-03256-y
View article
Argentina in a dark map. There are some colour spots marking the light pollution
18. Ursino, C.A.*; Rebolo-Ifrán, N. & Gorleri, F. (2022)

Impacts of light pollution on birds with a special focus on Argentina

El Hornero, 37(2): 33–37
DOI: 10.56178/eh.v37i2.393
View article
Grassland surrounded by a forest, with yellow flowers on the front of the image
17. Yang, C.; Peer, B.; Ursino, C.A.; Yu, J. & Rivers, J.W. (2022)

Evolution and Function of Acoustic and Visual Signals in Avian Brood Parasitism

Frontiers in Ecology and Evolution
DOI: 10.3389/fevo.2022.892373
View article
16. Ursino, C.A.*; Lama, F.; Reboreda, J.C. & De Mársico, M.C. (2022)

Vocal trickery allows the specialist brood-parasitic Screaming Cowbird juveniles to escape host discrimination after leaving the nest

Behavioral Ecology and Sociobiology
DOI: 10.1007/s00265-022-03175-9
View article
Figure of four different photos of young Screaming Cowbirds
15. Rojas Ripari, J.M.; Ursino, C.A.; Reboreda, J.C. & De Mársico, M.C. (2021)

Tricking Parents: A Review of Mechanisms and Signals of Host Manipulation by Brood-Parasitic Young

Frontiers in Ecology and Evolution
DOI: 10.1007/s00265-022-03175-9
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Decorative image to illustrate the thesis "Efecto de dos parásitos de cría sobre el cuidado parental de una especie con cría cooperativa, el Músico"
Ursino, C.A. (2016)

Efecto de dos parásitos de cría sobre el cuidado parental de una especie con cría cooperativa, el Músico (Agelaioides badius)

Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires
View Thesis
Decorative image to illustrate the thesis "Composición del grupo social y contribución de sus miembros al cuidado de los juveniles en una especie con cría cooperativa, el Tordo Músico Agelaioides badius (Aves, Icteridae)"
Ursino, C.A. (2008)

Composición del grupo social y contribución de sus miembros al cuidado de los juveniles en una especie con cría cooperativa, el Tordo Músico Agelaioides badius (Aves, Icteridae)

Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires
Decorative feature Image for the article "Nueva etapa del Departamento Científico de Aves Argentinas"
Ursino, C.A. & Roesler, I. (2020)

Nueva etapa del Departamento Científico de Aves Argentinas

Revista Aves Argentinas, 59: 38
View article
Decorative feature Image for the article "Libro de resúmenes XIX RAO"
Ursino, C.A. & Roesler, I. (2022)

Ciencia en Aves Argentinas

Libro de resúmenes XIX RAO
View article
Decorative feature Image for the article "Biblioteca digital de Aves Argentinas"
Ursino, C.A.; Roesler, I.; Jefferies, M. & del Castillo, M. (2024)

Biblioteca digital de Aves Argentinas

Revista Aves Argentinas, 70: 38
View article
Decorative feature Image for the article "Libro de resúmenes XX RAO"
Ursino, C.A. & Roesler, I. (2024)

Ciencia en Aves Argentinas

Libro de resúmenes XX RAO
View article
Decorative feature Image. It's a group photo of the members of the Aves Argentinas Scientific Department
Jefferies, M.; Ursino, C.A. & Roesler, I. (2024)

XX Reunión Argentina de Ornitología en Miramar de Ansenuza

Revista Aves Argentinas, 71: 38
View article

CV

Education

2016

PhD in Biological Sciences. University of Buenos Aires.

2016
2008

Licenciatura in Biological Sciences (equivalent to Master’s). University of Buenos Aires.

2008

Research Appointments

2020–present

Director of the Scientific Department at Aves Argentinas.

2020–present
2022–present

Postdoctoral Research Fellow at Princeton University.

2022–present
2019–2022

Presidential Postdoctoral Research Fellow at Princeton University.

2019–2022
2016–2019

Postdoctoral Argentinean National Science Council (CONICET) Fellow at University of Buenos Aires.

2016–2019
2017

Fulbright Fellow - Visiting Post-Doctoral Scholar at Princeton University.

2017
2014–2015

Visiting Graduate Student Fellow at Harvard University.

2014–2015
2011–2016

Graduate Student CONICET Fellow at University of Buenos Aires.

2011–2016

Service

2025–2027

Member, AOS Committee.

2025–2027
2025–Present

Associate Editor Ornithology.

2025–Present
2023–Present

Associate Editor El Hornero.

2023–Present
2024–Present

Associate Editor Frontiers in Bird Science.

2024–Present
2021

Guest Editor Frontiers in Ecology and Evolution.

2021
Realistic illustration of a Baywing bird sitting on a branch. The bird seems to be singing

Collaborators

I am fortunate to collaborate with outstanding researchers and research teams. Below are some of the key collaborators whose contributions have significantly shaped my work:

Group photo of Riehl Lab members. On the background there are trees and the ocean

Riehl Lab at Princeton University

I have had the privilege of working and continuing to collaborate with the members of this lab, all of whom have played an essential role in shaping my research. Below, I highlight some individuals whose work has been directly involved in my projects:
  • Christina Riehl – Postdoctoral adviser and still a close collaborator. Together with Christie, I began incorporating genetic tools into my research, which led to new research lines.
  • Maria Smith – Graduate student at the Riehl Lab. Maria and I have worked closely on lab-based research to understand social dynamics and mating behaviors in birds.
  • Josh Lapergola – Postdoctoral Researcher at the Riehl Lab. Josh and I have worked together analyzing the genetic data from my projects.
  • Meghan Strong – Lab Manager. Meghan and I have collaborated on an exciting study on the individual reproductive strategy of the brood parasite Screaming Cowbird, using DNA extracted from egg membranes.
Group photo of the LEYCA lab members, inside of one of the biological stations we work at

LEyCA Lab at the University of Buenos Aires and CONICET

I began my scientific journey here, and I’ve continued collaborating with many of its members, some of whom have become close friends. I still feel part of this flock. Below are my current collaborations:
  • J.C. Reboreda – Thesis adviser. We continue to collaborate on various projects.
  • Maria Cecilia De Mársico – Thesis adviser. Together, we explored a unique system in which two brood parasites share a cooperative breeder host.
  • Myriam Mermoz – We are exploring the genetic mating system of the Brown and Yellow Marshbird, using her impressive long-term database.
  • Vanina Fiorini – We have collaborated both in the field and the lab, investigating questions about brood parasitism and the impact of Philornis spp. on the European Starling.
  • Romina Scardamaglia – We have worked together to understand the genetic mating systems of brood parasitic species.

Edwards Lab at Harvard University

I spent two years as a visiting graduate student at the Edwards Lab, gaining invaluable experience and further developing my research skills. I am grateful for the support and collaboration of all the lab members, whose insights and expertise were crucial in advancing my work during that time.

CENPAT

  • Gabriela Palacios – Specializing in eco-immunology. Gabriela and I collaborated on understanding the immune responses of birds to ectoparasites.

Aves Argentinas

  • Gabriel Celedón – Former field technician. His work was invaluable in helping start a new research line with the Firewood-gatherer.

Community Roles

Decorative feature Image. It's a group photo of the members of the Aves Argentinas Scientific Department

Director, Scientific Department at Aves Argentinas

As the Director of the Scientific Department at Aves Argentinas, I lead a variety of scientific initiatives focused on advancing bird research and conservation, supporting fellow researchers, and fostering collaboration within the scientific community. I work with a diverse and amazing team. Some of my key contributions include:

Directing the Publication of Scientific Journals

I oversee the editing and publication of two scientific journals at Aves Argentinas: El Hornero, the oldest ornithological journal in the Spanish-speaking world (with over 100 years of history), and Nuestras Aves, which bridges the gap between bird watching and research. I am proud to contribute to their legacy.

We created and coordinate this program, locally known as “Becas Aves Argentinas” which provides funding to support early-career researchers. It encourages innovative research ideas and aims to foster the development of the next generation of ornithologists and conservation leaders.

I am actively involved in organizing and coordinating the National Ornithological Congress (RAO), a key event that gathers experts from various fields of ornithology and conservation. This congress serves as a platform for sharing knowledge and strengthening collaboration among researchers, conservationists, and bird enthusiasts.

Decorative image to illustrate Birds of the World digital platform

Birds of the World (BOW)

I collaborate with Birds of the World (BOW), reviewing Spanish ornithological journals and translating relevant and interesting information to make it accessible for the BOW platform. Additionally, I am beginning to coordinate the editing and updating of bird accounts. BOW is a valuable resource for avian knowledge, and I am pleased to contribute to its efforts in providing accurate and reliable information on bird species worldwide.
Field landscape image with tall grassland and a forest on the background. On the right side there is a hiding camouflaged tent for research purposes
Landscape image of a grassland surrounded by a small forest.
Two Firewood-gatherers birds standing on countryside wooden fences. They are both eating a small invertebrate which they are holding each on their beaks
Decorative image of a Lab testing
Baywing adult bird perched on a tree. Their body is half covered by branches and leafs
Seven bird eggs collected for research purposes, which were returned safely to the nest after studied
Bird chick very young, still developing his feathers. The skin shows clear signs of Philornis infection
Landscape of a grassland, with a small lagoon on the middle. There is also one small tree standing in the middle of the composition
Young bird with a radio telemetry antena, one of the research actions to study their movements
Four bird eggs, one is different, clearly from a parasitic species

Thanks

I am grateful to the following institutions for their support and funding, and for being part of my professional, academic, and research journey.

2025
American Ornithological Society Travel Grant
2024
Williams Foundation
2023
Wilson Ornithological Society Travel Grant
2021 – 2024
Co-PI – Grant of Argentinean National Research Council (CONICET)
2020
Postdoctoral Research Award – American Ornithological Society
2020 – 2023
Co-PI – Grant of Argentinean National Agency for Science Promotion
2019
Presidential Postdoctoral Research Fellowship and Grant
2017
Fulbright Postdoctoral Award. Short-Term Scholar at Princeton University
2016 – 2019
CONICET Postdoctoral Fellowship
2014
BecAR-Fulbright. Visiting Graduate Fellowship at Harvard University
2015
52th Animal Behavior Society Meeting, Alaska, USA.
2014
International Society for Behavioral Ecology Travel Grant
2014
15th International Behavioral Ecology Congress. New York, USA
2012
International Society for Behavioral Ecology Travel Grant
2012
14th International Behavioral Ecology Congress. Lund, Sweden
2011
Neotropical Ornithology Meeting, Cusco, Peru
2013
Best graduate student talk presentation at Reunión Argentina de Ornitología
2013
Bergstrom Memorial Research Award – Association of Field Ornithologists
2011
Best presentation at Neotropical Ornithology Meeting – Neotropical Ornithological Society
2011
Neotropical Ornithological Society travel grant
2011 – 2016
CONICET Graduate Student Fellowship
2007 – 2008
Beca Estímulo (outstanding undergraduate fellowship from the University of Buenos Aires)

Research

Mating System

My research on mating systems focuses on understanding the diverse reproductive strategies across species. I investigate how parental care shapes mating behaviors and how these behaviors influence genetic diversity within populations, particularly in species with and without parental care. By studying the mating systems of birds, I aim to uncover patterns of monogamy, promiscuity, and other complex social structures.
Mating systems of brood parasites are of particular interest in my research because these systems have evolved in the absence of parental care. Brood parasites, such as the Shiny Cowbird (Molothrus bonariensis) and Screaming Cowbird (Molothrus rufoaxillaris), are expected to be more promiscuous, given their reliance on other species to raise their offspring. However, behavioral observations reveal that while Shiny Cowbirds exhibit promiscuous mating behaviors, the Screaming Cowbirds may actually follow a more monogamous system, challenging the conventional understanding of parasitic mating systems.
Additionally, I study species with cooperative breeding systems, such as the Baywing (Agelaioides badius) and the Brown and Yellow Marshbird (Pseudoleistes visceralis), which offer a contrasting social structure. In these species, multiple individuals help raise the young of a single breeding pair, which provides insights into the evolution of social behaviors. This cooperative behavior may also shape the social and genetic mating systems, influencing both individual and group-level fitness. Understanding how social dynamics drive cooperative breeding offers a unique lens to examine the evolution of mating systems in birds.
My research combines behavioral observations and genetic analysis to explore how these mating systems evolve and how social structures influence mating strategies. Using advanced techniques such as double-digest restriction-site associated DNA sequencing (ddRad-seq) and mitochondrial DNA analysis, I aim to reconstruct family trees and uncover the genetic underpinnings of these mating systems.

Research

Brood Parasitism

Brood parasitism is a reproductive strategy in which one species relies on another to raise its offspring, avoiding the costs of parental care such as feeding and protecting the young. In birds, brood parasites lay their eggs in the nests of other species, leaving the host to care for the parasite’s young. My work focuses on understanding the eco-evolutionary consequences of the coevolutionary “arms races” that emerge between avian brood parasites, such as cowbirds, and their hosts. These arms races involve a continuous cycle of adaptation and counter-adaptation, where both parasites and hosts evolve new strategies to outcompete each other.
Through this research, I aim to answer several important questions: How do host species evolve mechanisms to detect and reject parasitic nestlings and fledglings? How do brood parasites exploit the host species, and how do they adapt to avoid host defenses? How do these parasitic interactions influence the evolution of host reproductive strategies and behaviors? How do specific host provisioning behaviors impact the begging calls of parasitic chicks and contribute to their survival?
To explore these questions, I conduct fieldwork in the Pampas region of Argentina, where I perform both observational studies and field experiments to track host-parasite interactions. This includes manipulating the presence of parasitic chicks in nests to observe host responses, as well as experimenting with vocal mimicry in cowbirds to test how hosts adjust their parental care. I also use genetic analysis to study patterns of parasitism and reproductive outcomes for both parasites and hosts.
I investigate these dynamics in two main systems: the current system involving Firewood-gatherer (Anumbius annumbi) and the Shiny Cowbird (Molothrus bonariensis), and my historical system involving two closely related brood parasites, the specialist Screaming Cowbird (Molothrus rufoaxillaris) and the generalist Shiny Cowbird (M. bonariensis), and a shared host, the Baywing (Agelaioides badius). Additionally, I have worked with other host species, such as the Chalk-brower Mockingbird (Mimus saturninus) and House Wren (Troglodytes musculus), to broaden our understanding of host-parasite dynamics.
My aim is to better understand the evolutionary and ecological consequences of brood parasitism, the evolution of host defenses, and how these interactions influence social and genetic mating systems.

Research

Ecto-parasitism (Philornis spp.)

Philornis spp. (botflies) are ectoparasites that pose a significant threat to many bird species by infesting nests and feeding on the blood and tissue of nestlings. The parasitic larvae of Philornis spp. can severely affect the health and survival of the host species, influencing both individual fitness and population dynamics. My research focuses on understanding the ecological and evolutionary consequences of Philornis spp. ectoparasitism and how host species adapt to this parasitic threat.
Through this research, I seek to answer several key questions: How do host species detect and defend against Philornis spp. larvae? How do parasitic infestations affect the fitness of host species? How do host species adjust parental care in response to ectoparasitic infestations?
My primary study systems include bird species in the Pampas region of Argentina, where Philornis spp. infest nests of various native and invasive bird species. I study these dynamics through extensive fieldwork, where I record nests and use a combination of observational studies, field experiments, and eco-immune assessments to evaluate how hosts respond to parasitic infestations and how these interactions impact reproductive success. For example, in my work on the Baywing (Agelaioides badius), I described a very peculiar defense mechanism against Philornis spp. larvae involving the removal of larvae from nests, a unique behavior that I have documented with videos—definitely worth checking out!
Additionally, I have examined the impact of Philornis spp. on growth, hematological and immune measures, and survival of nestlings of the invasive European Starling (Sturnus vulgaris), providing insight into how native ectoparasites can influence the success of invasive bird species.

Research

Cooperative Breeding

Cooperative breeding is a social system in which individuals, often offspring from previous breeding seasons, help a breeding pair care for their young. This system provides important insights into the evolution of cooperation, kin selection, and the ecological conditions that favor the emergence of such behaviors. It was the focus of my early scientific career and remains a key area of interest as I continue to explore the dynamics of cooperation in animal societies.
My research investigates how cooperative breeding systems adjust parental care in different ecological and social contexts. Key questions include: Who are the helpers? When do they join the nest? How do different ecological and social pressures influence parental care and helper recruitment?
Through fieldwork in Argentina and genetic analysis in the lab, I have studied how the parental care of cooperative breeders is influenced by the presence or absence of helpers, as well as how brood parasitism (whether from mimetic or generalist parasite) Philornis spp. ecto-parasitism affects these behaviors.