This post belongs to a series written by students in the Conservation Biology course BSC4052 at the University of South Florida. This course provides an overview of major themes in conservation practice and related applied problems in biology, including: population ecology in the context of conservation, patterns of diversity, valuing diversity, threats to diversity, management actions and strategies for preserving diversity.
Carley DeFillips is a native to Florida’s east coast, where she developed a passion for the local wildlife. Carley studies Environmental Biology at the University of South Florida where she does undergraduate research in an ecosystem ecology lab. After graduation, she plans to attend USF as a graduate student to study the effects of microplastics in wetlands. She hopes to use her education to aid in the conservation of Florida’s unique ecosystems.
Cover image: A juvenile Bonelli’s Eagle mid-flight. Credit: Wikimedia Commons
When the workweek ends and the weekend arrives, many people leave their office life to visit the great outdoors. From birdwatching to biking, spending time in nature may be a positive experience for you, but your presence may make the animals living in the natural spaces you visit on the weekend wish it was Monday already.
Animals who inhabit parks and preserves can suffer from the “weekend effect,” where increased visitation of parks during weekends and holidays causes greater disturbances to the organisms that reside there. This increased presence of humans during certain days can lead to changes in animal behavior. Animals often avoid human-visited areas which means they roam farther from home, spending more time away from their preferred feeding, breeding, or sleeping areas.
This potential change in habitat use led Arturoto Perona and his colleagues to study Bonelli’s eagles (Aquila fasciata) living in the Sierra de Espadán and Sierra Calderona Natural Parks in Eastern Spain (Perona et al., 2019). Although Bonelli’s eagles are not considered a vulnerable species by the International Union for Conservation of Nature (IUCN) due to their wide distribution across Europe and Asia, their European population has been shrinking dramatically from habitat loss and electrocution from powerlines (BirdLife International, 2019). Parks like the Sierra de Espadán and Sierra Calderona provide a much-needed refuge for these birds, but even within the parks, Bonelli’s eagles don’t have it easy.
Perona and his colleagues tagged 30 Bonelli’s eagles with solar-powered GPS units that tracked their ranging behaviors for a year and a half. At the end of the study, these scientists determined that on weekends and holidays the eagles tended to range farther from home than during the week.
While getting out of the house is a good thing for people, when the eagles leave their typical territory, they run into a problem: human infrastructure. Like many wildlife preserves, the Sierra de Espadán and Sierra Calderona are bordered by cities and towns. When the eagles leave the reserves to avoid the people that come to visit, they tend to enter the skies above human-dominated areas. More than fifty percent of Bonelli’s eagles die by electrocution from powerlines, and leaving the park during weekends and holidays increases this risk.
Beyond the risk of powerlines, there are other less obvious consequences to habitat use changes. For example, by roaming farther during periods of high human activity, the eagles leave their favorite hunting grounds and instead spend more time flying without finding food. Because this energy-burning behavior can occur many times throughout the year, the eagles could fail to meet the physical requirements needed for egg laying by the time the breeding season rolls around, potentially impacting future generations of the species.
Human presence doesn’t just affect the Bonelli’s eagle. Other organisms who inhabit parks or preserves experience similar stresses and respond in comparable ways. When people visit parks, seemingly harmless activities such as walking or biking generate noise that affects animal behavior. Animals see humans as predators, so naturally will exhibit anti-predatory responses. Animals respond to human disturbance in many ways: they may flee, take shelter, or change where they choose to forage for food. Many animals living in reserves will spend the weekend running or hiding from people rather than focusing on gathering food or finding a mate. The additive effect of avoiding humans every weekend could lower an animal’s overall fitness, defined as an animal’s ability to survive and reproduce in its environment. Parks are intended to be places where animals can prosper away from human interference, but the “weekend effect” presents unique dangers to these refuges.
Sharing the Park
Although humans may seem like the villains in this story, people shouldn’t stop visiting parks entirely. Instead, this research will help park managers make informed decisions about human-wildlife interactions. Providing space for wildlife to roam in a park is incredibly important, but it is becoming more obvious that animals also need some time to themselves. For example, changing a park’s operating hours during breeding seasons can help relieve some of the stress humans unknowingly put on wildlife. Limiting human interaction during critical periods for wildlife – such as breeding, nesting, or hibernation seasons – can ensure that both people and animals can effectively enjoy the benefits of wild spaces without causing harm to each other.
BirdLife International 2019. Aquila fasciata (amended version of 2016 assessment). The IUCN Red List of Threatened Species 2019.
Perona AM, Urios V, López-López, P. 2019. Holidays? Not for all. Eagles have larger home ranges on holidays as a consequence of human disturbance. Biological Conservation 231: 59–66. https://doi.org/10.1016/j.biocon.2019.01.010