Some hawks pack a punch: Secrets behind nest defense revealed

Stories about hawks and owls attacking people have made the news in recent years. However, there is more to these attacks than meets the eye. Authors of a new paper published in the Journal of Raptor Research illuminate this backstory in “Nest Defense Behavior of Suburban and Rural Red-shouldered Hawks.” Nest height plays a role in the defensive mentality of individual Red-shouldered Hawks (Buteo lineatus), as well as how familiar they are with human intrusions. Interestingly, personality could also be a factor — some hawks are just sassier than others.

True to their name, Red-shouldered Hawks sport lovely russet feathers on their “shoulders,” and are a favorite among hawk enthusiasts. In Ohio where this study took place, Red-shouldered Hawks are a common community member in both rural and suburban areas. Like other birds, they are protective of their nests, however, raptors face particularly high stakes when it comes to raising competent nestlings. Raptors produce relatively few young during their lifetime, and young hawks have a lot to learn. Hawk parents therefore invest more time and energy into their young than, say, ducks or geese. It doesn’t take much to teach a young bird how to “catch” algae. Catching live prey, however, requires practice.    

Dr. Cheryl Dykstra, from Raptor Environmental in Ohio and a team of researchers set up an experimental study during two breeding seasons to test three things: whether there was any difference between nest defense behaviors in urban versus suburban populations of Red-shouldered Hawks in southeastern and southwestern Ohio, whether environmental conditions played any role in aggressive nest defense, and whether or not nest defense resulted in higher reproductive success for a hawk pair. The team also looked at historical notes and interviewed landowners to glean a more comprehensive picture on hawk behavior over time within the study areas.

They found that suburban Red-shouldered Hawks demonstrated more aggressive nest defense behavior than their rural counterparts, however hits on people in both types of residential habitat were rarer than is often portrayed by the media. Hawks nesting in populated places are more familiar with humans, and likely less afraid of making their protective instincts known. Heightened aggression by urban raptors has also been documented for Burrowing Owls (Athene cunicularia), Eurasian sparrowhawks (Accipiter nisus), and Mississippi Kites (Ictinia mississippiensis).

Notably, the research team tested whether environmental factors correlated with aggressive behavior, and found that in suburbia, hawk parents with nests closer to the ground exhibited stronger aggressive defense behaviors that parents sitting on higher nests.

It is likely, based on observations of birds across taxonomic groups, that age, experience level, and personality of individuals play a role in nest defense behaviors. Boldness, in particular, is a relevant trait. Dykstra, who has been studying Red-shouldered Hawks for over twenty years, can easily recall individual females that repeatedly exhibited notable levels of boldness. “Personality traits are repeatable,” she says. “Animals are consistently bold or shy, neophobic or neophilic, fast explorers or slow explorers.” Red-shouldered Hawks, it turns out, are no exception.

Being hit by a raptor is a startling experience. And yet, landowners expressed appreciation for their locally nesting hawks, even if they had been the recipient of nest defense behaviors. Many members of the community, including kids, enjoyed seeing newly banded nestlings up close. Dykstra describes one of the primary impacts of this research as “increasing awareness of and protection for urban raptors.” She says they work primarily on private land, and therefore encounter many opportunities to discuss things like habitat conservation and the hazards of rodenticide use.

Urbanization is accelerating. Understanding the causes behind defensive behavior in raptors, as well as factors that impact probability of a hit (such as nest height), can help researchers, managers, and residents develop proactive approaches to mediate negative hawk-human interactions. “Understanding that a hawk is just trying to defend its young helps people empathize with the birds,” says Dykstra. This empathy, combined with well-informed preventative measures, like wearing a hardhat or using an umbrella, can lead to peaceful cohabitation between humans and their raptor neighbors.

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Paper

Dykstra et al. (2024). Nest Defense Behavior of Suburban and Rural Red-shouldered Hawks. Journal of Raptor Research, 58(4): 450-463. 
DOI: 10.3356/jrr2418

Notes to Editor:

1. The Journal of Raptor Research (JRR) is an international scientific journal dedicated entirely to the dissemination of information about birds of prey. Established in 1967, JRR has published peer-reviewed research on raptor ecology, behavior, life history, conservation, and techniques. JRR is available quarterly to members in electronic and paper format. 

2. The Raptor Research Foundation (RRF) is the world’s largest professional society for raptor researchers and conservationists. Founded in 1966 as a non-profit organization, our primary goal is the accumulation and dissemination of scientific information about raptors. The Foundation organizes annual scientific conferences and provides competitive grants & awards for student researchers & conservationists. The Foundation also provides support & networking opportunities for students & early career raptor researchers.