Friday, July 10, 2020

The Florida Burrowing Owl

Florida Burrowing Owl. Photo by Victoria Wright

Florida Burrowing Owl. Photo by Victoria Wright

By Nancy Richie

SPEOTYTO CUNICLARA FLORIDANA

This familiar Marco Island resident is named from the Greek words, “speo” meaning “cave” and “tyto” meaning owl and “cuniclara” derived from the Latin word cuniclarius meaning “little miner”. As the name suggests the Florida Burrowing Owl digs “caves” or burrows and is the only owl species that nests underground.

Background

The Burrowing Owl can be found from Canada to South America, mostly prevalent in the western states with an isolated population in Florida. Though migratory in the west, burrowing owls are year round residents in Florida, most commonly observed during the nesting and hatching season between the months of February and July.

Historically, these owls inhabited treeless grasslands and pastures of central and south Florida. The inland owl population has decreased due to disappearing natural habitat. This has caused the owls to be more innovative in their selection of habitat. Now coastal south Florida areas enjoy the scattered population in partially developed areas such as Broward and Dade counties, the City of Cape Coral and Marco Island. Habitats include golf courses, playgrounds, cultivated lands, such as farms, airport fields or, as we see here on Marco, cleared and mowed lots without trees. They do tend to favor well-drained dry, level open terrain with vegetation at low height. This helps improve their ability to see predators and detect prey. This in turn makes Marco Island’s undeveloped, regularly mowed lots the owls preferred habitat.

Description

Averaging only 9 inches in height on distinctly long legs with a wingspan between 20-24 inches, this owl is one of the smallest owl species. Though it lacks ear tufts and has no facial disc, there is no question it is an owl. Their bright yellow irises with expressive white eyebrows catch your attention immediately. The dorsal plumage of both the male and female is dark to sandy brown, with scattered white bars and spots that blend perfectly in the open sandy habitat the owl prefers. A dark brown collar around the neck, white abdomen, and white chin are common characteristics. The young resemble the adults in size and facial features but have rust colored, downy plumage on their throats and bellies.

Due to similar size and markings, the male and female are difficult to tell apart. However, during nesting season, the male has been observed to be paler or bleached by the sun, due to the amount of time he is sentinel to the nesting female within the burrow. The female appears darker due to the amount of time below ground and the staining of her plumage by the nest’s contents.

The preferred diet of the owls is larger insects, small amphibians and reptiles and occasionally small birds and mammals. They are not strictly nocturnal like all other owls, but hunt both day and night. They hunt by walking, running, and hopping after prey on the ground. Prey is caught with talons and transferred to the bill to carry and feed each other and the young. Indigestible food parts, mainly consisting of bone and fur, are regurgitated as pellets in and around the burrow entrance.

These “little miners” efficiently excavate a 5-12 foot burrow in less than two days using their long almost featherless legs to accomplish this task. The entire burrow structure consists of three parts: an entrance mound of the excavated soils, a curved tunnel that can be 6 inches in height, 8 inches wide, and 5-12 feet in length, and an enlarged nest chamber at the end of the tunnel. Only one entrance per burrow is the norm, but commonly observed on Marco Island, the male may dig a satellite (nearby) burrow during the nesting season that could be an anti-predatory strategy, (i.e. if a predator locates the active nest, a back-up nest is nearby for the chicks’ and female’s safety.) Typical for birds of prey, the same burrow or general location will be used year after year by the same pair of breeding adults.

Courting behavior begins with both male and female adults displaying unique flight patterns, preening each other and rubbing bills. During the courting, the pair will “decorate” the burrow mound with miscellaneous shiny objects and animal feces. This behavior is thought to camouflage the location and smell of the burrow from predators. Once the burrow is decorated, it is considered to be “active” or having a nest, eggs or flightless young present. With courtship successful, eggs are laid and the young are then brooded in the burrow chamber. Clutch sizes average between 5-8 small, round, white eggs that are incubated for 28-30 days. The female solely provides incubation while the male sits above ground guarding the nest and hunting food. During the nesting season, driving down the streets of Marco Island, such as Lamplighter or Goldenrod, you can count the round heads of owls “standing watch”. The adult breeding pairs will mate for life though if one dies, another partner will be quickly taken.

The young hatch in intervals a few days apart. At 10 days to three weeks of age the chicks emerge from the burrow. They are the approximate size of the adult, but fuzzy and copper-colored. Usually awkward and clumsy, they are not yet afraid of much. The owl parents hunt and feed the chicks until they are able to do so themselves. At about 42 days, the young can fly and hunt on their own – they are “fledged”. Once the young are fledged, the burrow is considered “inactive” or not containing a nest, eggs or flightless young. Due to a variety of predators (snakes, opossum, raccoons, osprey, dogs, and cats), food availability, urban development pressure, and flooding of burrows during heavy rains, typically, only 1 or 2 chicks reach maturity per nest. They then are ready to breed in one year’s time.

Burrowing owls do not have the “hooting” call we commonly associate with owls; rather they have a two-note call described as “coo-coooo”. Both male and females when defending the burrow will use a series of clucks, chatters and screams. You will experience these calls if you ever stand too close to an active nest!

Protection and Population

Protected federally by the Migratory Bird Treaty Act and listed by the state of Florida as a “species of special concern”, and also by the City of Marco Island Protected Species Ordinance, the city actively monitors and works with the state and federal authorities to ensure protection of this listed species. The “species of special concern” description means the burrowing owls, the nesting burrow, their eggs and flightless young are all protected by law from harassment and/or disturbance.

The City of Marco Island currently has approximate 89 properties with burrows posted. Last season, only 27 pairs produced young, down from the last season. This season there has been an increase of adult pairs displaying nesting characteristics. To date, 48 pairs have been documented. Staking an approximately 20-30 square foot diameter, the burrows are marked with orange flagging tape and a sign warning “Do Not Disturb”. Posting the nest sites with flagging tape and signage does help reduce disturbance or accidental destruction by lot mowers and other large equipment activity along the roadsides. Construction fencing is used as a barrier if extensive construction is taking place in the vicinity.

Long-time residents and newcomers alike have inquired why the City makes such a concerted effort to identify and protect these birds. Considering the fact that there seem to be so many here in Marco Island, why are these owls listed as protected species? One of the main threats to the owl’s survival is destruction of habitat. Due to agricultural and residential development, once thriving populations of burrowing owls in other parts of Florida have had severe decline and total extermination. Without protective measures, Marco Island’s owl population, a significant portion of the overall Florida population, may face the same fate.

Some people wrongly believe that a property cannot be developed if burrowing owls are present. That is not the case. If the burrow is outside the building footprint and can be roped off or surrounded by a silt fence creating a protection zone of about 6-10 feet, the property can be developed at any time. If maintaining that required protection zone through construction is not possible, the developer can request a permit from the Florida Fish and Wildlife Conservation Commission (FWC) to destroy the nest. This is required prior to receiving a City of Marco Island building permit. FWC will issue a permit if the nest is observed to be inactive. There is no fee for this permit. Collapsing any burrow without the FWC is both a State and City violation. Please contact FWC for the permit application at the following web address: www.myfwc.com.

The purpose of managing this species through permitting is to prevent active nests (containing nest, eggs or flightless young) from being destroyed. The nesting season is February 15 through July 10, and if the burrow is observed to be active, a permit will be on hold status until the young are fledged and carefully monitored to ensure the young owls are flying freely or have left the site. On Marco Island, approximately 50% of the adult owl population is observed year round, so if there is an owl present at the burrow outside nesting season, the burrow is considered inactive. Important to note, on Marco Island, due to warm temperatures, the nesting season starts earlier, mid to late January. Chicks have been seen as early as late February or early March.

What Can You Do?

Anyone interested is strongly urged to construct a “starter burrow” for the owl(s) to relocate when the original burrow is destroyed. It is easily done by simply clearing away about one to two feet of sod, dig an indentation that looks like a beginning of a tunnel or burrow and placing a t-perch next to indentation. To date, this has been successful at 4 out of 5 locations tried on the island. If more residents are interested in the opportunity to play an important (and rewarding!) role in the fate of this Species of Special Concern, it might be the answer to sustain a healthy, productive, bug-eating owl population for the Marco Island ecosystem. Free t-perches are available at City Hall.

For more information on burrowing owls, permitting procedures, and/or starter burrows, please call Nancy Richie, Environmental Specialist, City of Macro Island, at (239) 389-5003. If destruction or harassment of burrowing owls and/or their burrows is observed, please report to the City of Marco Island (239) 389-5000 and FFWCC Wildlife Alert 1-800-282-8002.

Nancy Richie is a long time Island resident and Marine Biologist.

 

Leave a Reply

Your email address will not be published. Required fields are marked *