NA­TURE’S NOTE­BOOK

A very habi­tat-spe­cific species fond of scrub oak

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Florida Scrub Jay

The Florida scrub jay ( Aph­e­lo­coma coerulescens) his­tor­i­cally roamed the Florida penin­sula, but its distri­bu­tion has al­ways been frag­mented within its range. The scrub jay is ex­clu­sively as­so­ci­ated with scrub oak habi­tat and re­quires that habi­tat to be in the early stages of veg­e­ta­tion suc­ces­sion where the trees are 10 feet or less and the habi­tat is in­ter­spersed with open sand. It can­not oc­cupy scrub oak habi­tat that has greater than 50 per­cent canopy cover of non­scrub trees such as sand pine and tur­key oak. Scrub oak veg­e­ta­tion is as­so­ci­ated with well-drained, white, fine, siliceous sands de­posited dur­ing the Pleis­tocene high sea-level era.

Ex­am­ples of scrub oak veg­e­ta­tion in­clude myr­tle oak, Chap­man oak, scrub oak and sand live oak. Other veg­e­ta­tion that can be scat­tered through­out scrub habi­tat is saw pal­metto, scrub pal­metto, gar­be­ria, silk bay, Florida rose­mary and rusty ly­onia. Sand pine and tur­key oak can be scat­tered through­out Florida scrub jay habi­tat if they are less than 20 to 50 per­cent canopy cover. Scrub oak habi­tat re­quires a nat­u­ral or pre­scribed burn ev­ery 10 to 20 years.

The Florida Fish and Wildlife Con­ser­va­tion Com­mis­sion and the United States Fish and Wildlife Ser­vice have listed the Florida scrub jay as a threat­ened species. Its pop­u­la­tion was es­ti­mated to be 7,000-11,000 birds in 2001, pre­dom­i­nantly on the Mer­ritt Is­land/ Cape Canaveral Com­plex, Ocala Na­tional For­est and south­ern Lake Wales Ridge. These three sub­re­gions are the “core pop­u­la­tions” of Florida scrub jays be­cause this is where more than 50 per­cent of the scrub jay pop­u­la­tion is found.

The Gulf Coast has smaller sub­pop­u­la­tions that are iso­lated to vary­ing de­grees. Ex­ten­sive habi­tat frag­men­ta­tion and loss of scrub oak habi­tat has oc­curred in this re­gion, which ex­tends from Levy County south to Lee County. Con­se­quently, this pop­u­la­tion has been di­vided into two sub­re­gions: the North­ern Gulf Coast and the South­ern Gulf Coast.

The Florida scrub jay is ap­prox­i­mately the same size as a blue jay, but the two do not re­sem­ble each other. The scrub jay is 10 to 12 inches in length and weighs ap­prox­i­mately 2.5 ounces (fe­male) to 2.7 ounces (male). Its crown, nape, wings, rump and tail are dull blue, and it is pale gray on its belly and back. A neck­lace of blue feath­ers sep­a­rates the gray un­der­parts from the white throat. The male and fe­male are in­dis­tin­guish­able in ap­pear­ance and can be told apart only by the fe­male’s “hic­cup” calls. Scrub jays less than five months old have a duller over­all body color, and the head and neck are dusky brown rather than dull blue found in adults. The blue jay has a crest, shorter tail and legs, bold black mark­ings and con­spic­u­ous white-tipped tail and wing feath­ers. The scrub jay is non­mi­gra­tory. It is a monog­a­mous and co­op­er­a­tive breeder. The non­breed­ing young (about two years old) as­sist the breed­ing pairs in all rear­ing and ter­ri­to­rial ac­tiv­i­ties. A breed­ing unit size is usu­ally three but can in­clude up to six helpers. This co­op­er­a­tive breed­ing so­cial struc­ture is most likely a re­sult of evo­lu­tion­ary adap­ta­tion for sur­viv­ing Florida’s frag­mented scrub habi­tat. The Florida scrub jay is sex­u­ally ma­ture at one year but usu­ally does not breed un­til the age of four. It is still able to breed at the age of 14. The breed­ing sea­son lasts about 90 days from March to the end of June. Scrub oaks in­clud­ing sand live oak and myr­tle oak are pre­ferred for nest­ing. Nests are con­structed 3 to 6 feet above ground. Nests, which are 7 to 8 inches in di­am­e­ter, are con­structed with oak twigs formed into a thick cup lined with sa­bal pal­metto fibers. Both the fe­male and the male gather nest ma­te­rial, con­struct the nest, and feed and at­tend the young. The fe­male does all the in­cu­bat­ing and brood­ing, dur­ing which the male brings her food. Clutch size av­er­ages two to five eggs. In­cu­ba­tion lasts for 18 days, and fledg­ing oc­curs 18 days af­ter that. A scrub jay pair can have one to four broods per sea­son. Ter­ri­tory size av­er­ages 24 acres with a den­sity of two to six scrub jays per 100 acres. They feed mostly on in­sects in the spring/sum­mer and acorns in the fall/win­ter. Preda­tors in­clude many species of hawks, owls and snakes, as well as bob­cats. Threats are fire sup­pres­sion, agri­cul­ture con­ver­sion and sub­ur­ban de­vel­op­ment. The best sites to ob­serve these peo­ple-friendly birds are Arch­bold Bi­o­log­i­cal Sta­tion near Lake Placid, Lake Wales Ridge State For­est, Mer­ritt Is­land Na­tional Wildlife Refuge, Ocala Na­tional For­est and Os­car Scherer State Park in Sara­sota County. Wil­liam R. Cox has been a pro­fes­sional na­ture pho­tog­ra­pher and ecol­o­gist for more than 35 years. Visit him on­line at williamr­cox­pho­tog­ra­phy.com.

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