| Behavior | Description |
|---|---|
| Hunting | Fishing in or near rivers, lakes, and oceans. |
| Theft | Taking food from other animals. |
| Courting | Aerial displays and gift-giving to attract mates. |
| Mating | Procreation, cloacal pressing. |
| Self Feeding | Intake of food for self. |
| Directed Feeding | Regurgitating food to young. |
| Social Feeding | Sharing food with other eagles. |
| Self Grooming | Cleaning feathers and preening of self. |
| Social Grooming | Cleaning feathers and preening of other eagles. |
| Resting | Resting in nests or on tree branches. |
| Sleeping | Sleeping in nests or on tree branches. |
| Defending Territory | Protecting nesting areas from other predators, standing guard. |
| Out of Nest | Moving outside of nesting areas for food or migration. |
Observational Ethogram of H. leucocephalus: A Study on Bald Eagle Behavior
Introduction
The Bald Eagle, Haliaeetus leucocephalus, is a bird of prey native to North America, known for possessing a distinctive white head and tail against an otherwise dark brown body. H. leucocephalus is found across all of the contiguous United States, most of Canada, and the northern-most portions of Mexico (Garrett et al., 1993). H. leucocephalus is known as a sea eagle, which refers to the habitat and niche of the bird to be near large bodies of water satisfying the dietary preference for small mammals, reptiles, and various species of fish (Newsome et al., 2010). The nesting locations of this bird of prey is influenced by the habitat, rearing methods, and dietary preferences which confer ecological benefits. Old-growth forests near marshes or open waters are typical, especially in the presence of hard-wood conifer super-canopies (Mundahl et al., 2013).
There is considerable ecological significance to the behavior and nesting of H. leucocephalus; this bird of prey is a noted apex predator and keystone species. As such, significant conservation efforts have been made to track and investigate the species in population numbers, rearing behavior, and the preservation of their habitat (Bergen et al., 2022). H. leucocephalus is particularly well studied in courtship / mating, as well as its hunting behavior. It is common for this species of bird to harass and steal the catches from other birds of prey, such as the osprey (Hansen, 1986). However, human involvement in deforestation, commercial fishing, and hunting has resulted predicted shift in the range and behavior of this species (Bergen et al., 2022).
This paper serves as an initial look at the behavior of H. leucocephalus. The subjects of this study are a pair of Bald Eagles in the southwestern region of Florida. More specifically, the subjects are a female adult and a juvenile aged approximately six months. This study will utilize a standard ethogram and activity budget approach in order to catalog and classify the frequencies of various behaviors. This approach provides a quantitative measure of specific behaviors and provides analytic support for the purpose of each behavior. The subjects of this study were observed using live-stream video capture and was reviewed multiple times for the purpose of ethogram construction and data gathering.
Methods & Materials
All observations were conducted by watching segments of the Southwest Florida Eagle Cam. Some observations were captured by observing segments of historical video footage. The segments of historical video footage was selected at random such that there was no duplication of viewed footage. The construction of the ethogram was conducted within a half-hour observation that was conducted on Monday, February 12th at 11:00 AM CST. This corresponds to the live-stream footage of 12:00 PM EST which was selected to increase the likelihood of observed behaviors displayed by the organisms. The produced ethogram includes other typical behaviors not observed within the initial window.
The indicated behaviors stated in the proposed ethogram was then recorded four additional times. During this sequence of observations, the behaviors were recorded at increments of 30 minutes. These observations were taken twice during the day, and twice at night. In order to ascertain these time windows, recent historical video footage was utilized. The behaviors were timed by using a stop-watch for both the primary adult female and the primary juvenile. Data related to any foreign courting males were not reported for the purpose of this study.
Results
The various behaviors tracked in the ethogram are reported in the following bar plots. The first plot represents the discrete time data recorded for each of the four trials. The second plot represents the average time data across all four trials.
The findings above are of interest for a few different reasons. While the plots are not separated by adult and juvenile H. leucocephalus, it is clear that there are incidents of hunting and thieving which were exclusively performed by the fully matured eagle. The vast majority of sleep was performed by the fledgling juvenile who has not yet left the nest. There was some instances of sleep performed by the adult female, but the female was typically not present in the nest during the night. This is typical as adult eagles are diurnal and perch during the night away from the nest.
In the later months of the development, the juvenile eagle was observed attempting to imitate the perching behavior of the adult female. This resulted in the juvenile being attacked by an owl and falling off the perch. However, the juvenile does have fledgling feathers and was able to recover back to the nest in the morning after the attack. The adult female eagle was not visible during this attack.
A significant amount of time was spent on feeding by the juvenile and the adult. The feeding behavior was typically constitutive of self and directed feeding by the adult, where directed feeding is the process of regurgitation delivery to the juvenile. However, as the juvenile continued to develop, the regurgitation directed feeding declined and was replaced by social feeding where the adult and juvenile shared hunted or stolen prey.
There was one lone instance of another adult eagle entering the nest. Sexing the foreign individual was difficult, however it is presumed that this was a male eagle engaging in courtship through the procurement and placement of nesting material. It is notable that this behavior took place only after the fledgling juvenile was out of the nest, but the juvenile did return to the nest later that same day.
