The Life History of Florida's Crested Caracaras

Special thanks to Joan Morrison for contributing her time to be interviewed for our blog.

Biologist Joan Morrison holds a tagged Crested Caracara just prior to its release. Photo by Jennifer Korn.

Crested Caracaras, as biologist Dr. Joan Morrison describes this species, are "sedentary and smart, and nesting pairs occupy a well-defined home range." While such traits make a Caracara what it is, it also means the species is not especially well-studied. Joan explains, "There's so much scientific interest in migratory species and the movement data that they produce. That's really cool. Frankly, the telemetry data that Caracaras produce are a little bit boring because they don’t move around much!"

A group of Crested Caracaras foraging. Photo by James Dwyer.


Their resident, localized nature, Joan believes, may also make the Crested Caracara more vulnerable to extirpation, at least in Florida, where the population is isolated and relatively small. Without movement by individuals in or out of the south-central Florida population to, for example, the more widely distributed Caracara population in Texas, Florida's Caracaras suffer reduced genetic diversity. What's more, Caracaras in Florida face habitat loss as land conversion projects alter their preferred habitat.

Such factors underscore the importance of better understanding this captivating falcon. Questions about the Florida population of Caracaras have led Joan to devote more than 30 years of research to understanding the species’ life history, with special focus on the effects of habitat loss.

A Localized Species

When PTTs (Platform Transmitter Terminals) first emerged in the 1990s as a means to track and observe animal movement, many researchers heralded their groundbreaking ability to track migratory movement in particular. For Joan, however, this technology wasn’t particularly helpful for studying Florida Caracaras because they do not make long-distance movements. Because Caracaras are nonmigratory and occupy a limited range in Florida, "[The PTT units’ functionality within] a kilometer of accuracy just wasn't working for me, because Caracaras are very sedentary and have specific home ranges and hardly ever leave them," explained Joan.

Data received from GPS/GSM transmitters can elucidate spatial relationships among neighboring Caracara territories. Other than the occasional excursion outside the generally used area, data show how faithful a Caracara is to its territory. (Nests are identified by red dots; other dots represent individual birds.) In areas where locations of neighboring birds overlap, there may be some clearing or other activity that favors Caracaras foraging there.


Through the mid-2000s, VHF transmitters remained the technology of choice for Caracaras in Florida. During that time, one of Joan’s Ph.D students investigated movements of young Caracaras immediately after fledging and discovered a network of communal roosts that these birds traveled amongst. The ability to track the same birds during both breeding and non-breeding seasons revealed a new insight: the young birds traveled most frequently and more widely during the breeding season, presumably looking for openings in territories.
A pair of Crested Caracaras perch on an antenna. Photo by Jennifer Korn.

Outwitting Telemetry

Around 2010, with PTT technology now more accurate and lightweight enough for Joan's research needs, she and a postdoctoral student tagged 8 Caracaras with PTT units, eager to obtain data. How did that go over with the Crested Caracaras? As Joan put it, "Most of the transmitters came off within a few weeks." Why? "The birds HATED them. They ripped them off and broke the antennas." Some species are just not suited for certain elements of telemetry, Joan explained. The external antenna was a required component of the PTTs for receiving a signal, but that antenna is what the Caracaras didn’t like. Failure of the Caracaras to accept the PTT technology resulted in a halt to her telemetry-based research, at least for a while.

With the emergence of GPS/GSM transmitters, however, Joan recognized an opportunity. GSM devices feature an internal antenna. "Without an external antenna to damage, these new transmitters were a promising alternative to use on the tag-destroying Caracaras."

The ES-400 features an internal antenna, making it suitable for outfitting on Crested Caracaras. Photo by LeeAnn Cooper.

Fortunately for Caracaras and for Joan, the new GPS/GSM units (some of her first units came from Cellular Tracking Technologies) proved successful. Even so, capturing and tagging Crested Caracaras requires an experienced person in the field. "The way that I put the backpacks on is so specific," said Joan, "because I know that they will try to take them off." Indeed, one tradeoff in banding and tagging an intelligent species is accepting that they will sometimes outwit their transmitters. She related, "Allopreening is a behavior in which a pair of birds will preen each other. It's a pair-bonding behavior and also an appeasement behavior. During allopreening, one bird can figure out how to remove the other bird's transmitter."

Allopreening, as demonstrated here by Black Vulture and Crested Caracara pairs, can result in transmitter removal. Photo by P. Raney.

In the event that a bird's transmitter is removed, recapturing the Caracara to retag it is nearly impossible. "It is extremely difficult to recapture a Caracara and put another transmitter on it," Joan explained, “because they remember how they were initially captured, and they know to avoid repeating the experience." Another barrier to successful transmitter performance can be feathers. "Caracaras have very long nape feathers that can cover the solar panel, so the units need to be offset so that doesn’t happen," Joan explains. "We asked CTT to alter the design a bit to account for this. When we first tag a bird, we also clip the nape feathers as additional insurance that the solar panel will receive sufficient charging."

This CRCA sports freshly clipped nape feathers. Photo by R. David Isley.


The CTT transmitters Joan currently uses include the ES-400 and the ES-420. In her experience, these transmitters are very accurate, and they allow for flexible programming--meaning Joan is able to monitor nocturnal roosting behavior, which was previously poorly understood.

Private Land for Habitat 

Now that the form and weight of GPS/GSM transmitters suited her species, in 2015, Joan began studying how land conversion projects that have incidental take permits affect Caracaras. Many of these projects are part of the Comprehensive Everglades Restoration Plan (CERP), which is designed to restore water flow and wetlands throughout south and central Florida and to create reservoirs for flood protection. As such, these projects often involve altering agricultural landscapes, including grasslands and pastures. “A take permit,” explained Joan, “allows for removal of trees where Caracaras often like to nest, as well as removal of acres of foraging habitat. Agencies that conduct these conversion projects often site them in the upland habitats. The uplands in Florida are actually incredibly important [to vulnerable species] because when there is flooding, or hurricanes, these uplands serve as refuges for many species that are seeking higher ground." Besides Crested Caracaras, vulnerable species like Burrowing Owls, Indigo Snakes, Gopher Tortoises, and Sandhill Cranes also inhabit these uplands.
A view of the Crested Caracara's preferred terrain. Photo by Joan Morrison.
In short, when a take permit is issued for wetland restoration, a deepwater reservoir installation, or a housing/agricultural development project, the entire habitat is transformed. The habitats affected by these projects are often grassland or pasture with palm and oak trees, and the projects often require removal of the trees as well as transformation of the grassland and pasture. With the loss of both the foraging habitat and trees that Crested Caracaras require for nesting, nesting pairs are often forced away from project areas into neighboring habitat. It's these displaced birds that Joan would like to better understand: what happens to them? To where do they relocate? Do they successfully reproduce after being displaced?
Many redistributed Crested Caracaras establish territories on private land. Photo by Paul Gray.

Her concern? As the number of land conversion projects and associated take permits increases, Crested Caracaras are increasingly forced to move in response to these changes in the landscape. As Caracaras are forced to relocate, they often establish territory on private land, such as ranches. Because there is often no or limited access to these areas, capturing and tagging Caracaras becomes even more challenging--and underscores why deploying transmitters, when possible, is vital for research. 

Monitoring Florida’s Crested Caracaras has contributed to a better overall understanding of this understudied falcon, and research has provided many examples of the challenges facing the south-central Florida population of this threatened species.