How Citizen Scientists Helped Crack the Case of the Crested Caracara's Diet
A revolutionary method is transforming how we study what raptors eat, and the discoveries are rewriting our understanding of their lives across the Americas.
The Feathered Enigma: Why Study Raptor Diets?
Imagine attempting to document the dining habits of a bird across millions of square miles, from the scorching deserts of Arizona to the steamy wetlands of Argentina. For centuries, understanding a raptor's diet required painstaking fieldwork—collecting bones and pellets from nests or spending countless hours in observation blinds.
But today, a new tool has given researchers an unprecedented view into the lives of these magnificent birds: the digital photograph. In a groundbreaking study, scientists have turned to photographs sourced from online citizen science platforms to uncover the dietary secrets of the Crested Caracara on a continental scale.
Understanding what raptors eat is far more than a simple catalog of their prey. Dietary studies are essential to understanding a species' ecology and resource needs through time and space 1 . The food a raptor consumes influences everything from where it chooses to live and how it interacts with other species to its reproduction and survival rates 1 .
Traditionally, scientists relied on methods like analyzing regurgitated pellets, collecting prey remains from nests, or direct observation 5 . While valuable, these approaches have significant limitations. They often provide data only at a local level and are frequently restricted to breeding pairs during the nesting season, missing non-breeding birds and seasonal variations 1 5 .
"The increasing use of citizen science data has the potential to provide dietary inferences at larger spatial, demographic and temporal scales," the study authors note, highlighting the power of this new approach 1 .
The Method: A New Lens on an Old Question
The Power of the Crowd
To tackle the challenge of understanding the Crested Caracara's diet across its vast range, researchers turned to two massive online databases: Macaulay Library and iNaturalist 1 . These platforms aggregate millions of wildlife observations and photographs uploaded by professional and amateur naturalists alike.
Image Filtering
Each image was visually examined by two researchers to confirm it showed a feeding event 1 .
Data Extraction
For qualifying images, researchers recorded the caracara's age, identified the food item, and noted the location and date 1 .
Duplicate Removal
To avoid overcounting, duplicate photographs of the same feeding event were identified and removed based on location, timing, and visual features 1 .
In total, 1,555 photographs of feeding caracaras, spanning from 1987 through 2022 and covering the species' entire range, were included in the analysis 5 .
The Scientist's Toolkit
This revolutionary approach relies on a surprisingly simple set of "research reagents" that have democratized the study of raptor diets.
| Resource | Function | Accessibility |
|---|---|---|
| Macaulay Library | Digital media archive specializing in birds; provides verified photographs with metadata | Publicly accessible; photographs available for non-commercial research |
| iNaturalist | Social network of naturalists; crowdsources observations and identifications | Publicly accessible; data available under creative commons licenses |
| Photographic Evidence | Captures feeding events in real-time across vast geographic areas | Provides data across seasons, ages, and regions not feasible with traditional methods |
| Researcher Verification | Ensures accurate identification of birds, age class, and prey items | Critical for maintaining scientific rigor in citizen science data |
A Continental-Scale Experiment: Unveiling the Caracara's Diet
This study represents a natural experiment of unprecedented scale, using passively collected data to answer specific ecological questions.
Surprising Results and Analysis
The analysis of these 1,555 photographs yielded fascinating insights that challenged some expectations and revealed striking geographical patterns.
Unexpected Age Similarity
Contrary to what we see in some raptor species, the study found no significant differences in the dietary preferences between adult and non-adult Crested Caracaras 5 . Both age groups consumed similar proportions of different food groups.
Diet Composition by Age
| Food Group | Adult Birds | Non-Adult Birds |
|---|---|---|
| Mammals | Commonly consumed | Commonly consumed |
| Birds | Present in diet | Present in diet |
| Reptiles | Present in diet | Present in diet |
| Fish | Occasionally consumed | Occasionally consumed |
| Invertebrates | Occasionally consumed | Occasionally consumed |
Latitudinal Effects on Food Group Probabilities
| Food Group | Northern Population | Southern Population |
|---|---|---|
| Fish | Probability increases toward equator | Probability increases with latitude |
| Invertebrates | Probability increases toward equator | No significant latitudinal pattern |
| Mammals | Probability increases away from equator | Probability increases away from equator |
These patterns align with global trends in species diversity and availability—ectothermic prey like reptiles, fish, and invertebrates become more diverse and abundant in warmer tropical regions closer to the equator, while mammalian prey dominates at higher latitudes 1 .
Crested Caracara Range and Diet Variation
Interactive visualization showing the geographic distribution of Crested Caracaras and dietary variations across their range.
The Bigger Picture: Raptor Diets in a Human World
The implications of this research extend far beyond understanding one species' menu preferences. The study demonstrates the powerful role that citizen science and open-source data can play in modern ecological research 5 .
Cost-Effective Research
This approach makes raptor dietary studies accessible to researchers without extensive field budgets 1 .
Continental Scale
Provides a model for studying other widespread species across their entire ranges 1 .
Temporal Depth
Data spanning decades reveals patterns that would remain invisible in localized studies.
"Assuming the focal species is well-sampled, web-sourced photography can improve our understanding of raptor diets at large-scales and complements more traditional approaches" 1 .
Conclusion: A New Era of Ecological Discovery
The story of the Crested Caracara's diet reveals a profound truth about the natural world: even a widespread generalist predator shows remarkable dietary flexibility across its range, shaped by the complex interplay of local ecology, latitude, and prey availability.
This research represents more than just an exploration of one bird's feeding habits—it showcases a fundamental shift in how we can study nature. By harnessing the power of citizen science and digital technology, researchers can now answer ecological questions at previously unimaginable scales, from a single backyard to an entire continent.
Your Role in Science
The next time you photograph a bird of prey, remember that you might be contributing to a scientific discovery that helps us better understand, and ultimately protect, these remarkable creatures and the ecosystems they inhabit.