In Chile’s Bosque Fray Jorge National Park, a place long known for its arid conditions, owls have begun altering what they hunt. Rising temperatures and more frequent drought have coincided with measurable changes in the birds’ diets over more than two decades. The adjustments appear tied to resource availability rather than any single dramatic event.
Long-Term Data Reveal Dietary Patterns
Researchers examined nearly 17,000 owl pellets gathered between 1990 and 2015. Inside those pellets they identified roughly 75,000 individual prey remains spanning 24 species of mammals, birds, reptiles, amphibians and arthropods. The work, published in the journal Ecography, tracked three owl species across years that grew steadily warmer and drier. Temperature stood out as the factor most closely linked to shifts in the number of different prey types consumed. Drought periods also prompted each species to narrow its focus, yet the overall variety of items in the diet rose after 2003. These patterns emerged from consistent field collections rather than short-term observations.
Each Species Responds Differently
The great horned owl showed the widest range of prey, taking both vertebrates and invertebrates such as beetles, scorpions and rodents. The American barn owl concentrated more on small mammals while still displaying moderate variety. The burrowing owl remained the most specialized, relying heavily on arthropods including beetles, grasshoppers and spiders. During drought years the three species diverged further in their choices, each emphasizing a different main food source. Such specialization can reduce direct competition when resources tighten. At the same time, the long-term increase in dietary richness suggests the owls encountered or pursued additional options as conditions changed.
Implications for Predator-Prey Networks
Lead author Angéline Bertin noted that changing environmental conditions are reshaping predator–prey interactions. As climate change intensifies, the fragility of these ecological networks may become more pronounced. The findings underscore how resource availability and temperature together influence what predators can reliably catch. The study does not claim that every future drought will produce identical shifts. It also leaves open questions about whether the new prey items represent permanent additions or temporary responses. Continued monitoring would help clarify whether the observed trends persist or reverse under different weather sequences.
What Observers Can Watch Next
– Continued pellet collections in the same park to track whether dietary richness keeps rising or stabilizes.
– Comparisons with owl populations in other arid regions facing similar temperature increases.
– Assessments of how changes in owl diets affect the populations of their new or expanded prey species. These steps could reveal whether the adjustments support greater ecosystem resilience or signal growing stress on the food web. The Chilean data provide one clear example of how warming and drought already alter everyday hunting behavior in a well-studied predator.
