Aphelocoma coerulescens

Geographic Range

Florida scrub jays, Aphelocoma coerulescens , occur from the Florida panhandle through central Florida. Florida scrub jays previously occupied most of the counties of peninsular Florida, they are currently found from Flagler, Marion, and Citrus counties in the north to Collier, Glades, and Palm Beach counties in the south.

• Biogeographic Regions
• nearctic nearctic
  • native native

Habitat

Aphelocoma coerulescens is a habitat specialist, living mainly in scrub woodlands of peninsular Florida. These birds prefer thickets of sand pine and scrub oak, recently burned sites, and shore-dune thickets, all habitats found on the sandy soils of this area. Aphelocoma coerulescens is found in scrub habitats along coasts, rivers, and on some high inland ridges. They will not generally nest in heavily forested areas. Dominant tree species in Florida scrub jay habitat are sand live oak ( Quercus virginiana ), Chapman oak ( Quercus chapmanii ), myrtle oak ( Quercus myrtifolia ), and scrub oak ( Quercus inopina ). Florida scrub jays may also be found in suburban areas.

• Habitat Regions
• temperate temperate
• terrestrial terrestrial

• Terrestrial Biomes
• scrub forest scrub forest

• Other Habitat Features
• suburban suburban
• riparian riparian

Physical Description

Aphelocoma coerulescens is usually between 25 and 30 cm long and weighs about 77 grams. The plumage of adult males and females looks alike, but males are slightly larger than females. The head, nape, wings, and tail are pale blue. The back and belly are pale gray. The throat and chest are white and bordered by a blue gray bib. Juveniles differ in appearance from adults in that they have dull or dark brown upperparts. Florida scrub jays look similar to other jays ( Cyanocitta ), but do not have a crest, white-tipped wings or tail feathers, or black barring. Molting occurs between June and November, and is at its highest between July and September. During late summer and early fall juveniles cannot be distinguished from adults.

• Other Physical Features
• endothermic endothermic
• homoiothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• male larger

Reproduction

Florida scrub jays mate for life. This species uses a technique called cooperative breeding, where extended families live together but have only one breeding pair. Courtship of a breeding pair is drawn out, with males using vocalizations and posturing to attract females. Average nesting groups consist of three birds, but can range from two to eight. Helper birds are usually the young of the original breeding pair. Copulation is discreet and not visible to other jays. Helper jays help the breeding pair by defending the territory and providing food for young. Helper birds are reproductively capable, and evidence suggests that they delay breeding because they are unlikely to be successful in reproducing. When helpers do go on to become breeders in a new nest, males generally inherit their natal territory when the breeding male dies. Females emigrate from their natal area. If the mate of a breeding adult dies, that adult may take on helper roles and relinquish their role as a breeder.

• Mating System
• monogamous monogamous
• cooperative breeder cooperative breeder

Nesting occurs from early March to late June. Florida scrub jays breed for the first time between the ages of 1 and 7 years, with most individuals breeding for the first time between 2 and 4 years of age. The eggs of are pea green to pale glaucous green and spotted with irregularly shaped markings. Helper male birds have lower testosterone levels than breeding males.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• fertilization fertilization
• oviparous oviparous

Fledglings depend on adults for food for about 10 weeks. Only the breeding pair builds the nest; which is about 18 to 20 cm in outer diameter, and 9 to 10 cm inner diameter. Nests are usually 1 to 2 meters from the ground. Only the breeding female incubates the eggs. Feeding of fledglings is done by both the breeding pair and helper birds. Helper birds do not incubate eggs or brood nestlings. Florida scrub jays use a lookout technique to watch for predators where one bird is chosen as the lookout and watches for oncoming attacks from a high position. Breeders and helpers will help chase away egg predators, which can be other species or other Florida scrub jays.

• Parental Investment
• altricial altricial
• pre-fertilization
  • provisioning
  • protecting
    • female
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • male
    • female
• pre-weaning/fledging
  • provisioning
    • male
    • female
  • protecting
    • male
    • female
• pre-independence
  • protecting
    • male
    • female
• post-independence association with parents
• inherits maternal/paternal territory

Lifespan/Longevity

Average lifespan is 4.5 years, but Florida scrub jays are known to live for up to 11 years in the wild.

Behavior

Aphelocoma coerulescens is both social and territorial. Family members cooperate in breeding, hunting, and defense. They are strongly territorial and use a lookout system to keep other members of the nest safe from harm. One bird perches on a high point and looks for predators. When one is spotted, the lookout gives a specific call to alert family members to take cover. Females use a distinctive hiccup call when interacting with other individuals. Nesting groups of A. coerulescens work together in foraging and territory defense. There is a dominance scheme in the family structure, breeding males are most dominant, followed by helper males, breeding female, and helper females. The breeding territory is inherited by the helper male when the breeding male dies or is unable to continue to breed. The helper females branch out from the nesting area and assume breeding roles in other territories when they leave the nest. Birds from one territory have been known to work together to prey on the eggs from another brood. This has been known to occur when only the breeding female is protecting the eggs and a group of invading individuals come near the nest. The breeding female head bobs and hiccups at the intruders and chases after them when they get too close to the nest. While she is chasing one intruder, another may enter the nest and steal an egg. These birds are also known to practice cooperative hunting of other species. Individuals may mob a large vertebrate in defense or hunting, and also have been observed to hunt snakes in pairs. Florida scrub jays are diurnal.

• Key Behaviors
• arboreal arboreal
• flies
• diurnal diurnal
• motile motile
• sedentary sedentary
• territorial territorial
• social social
• dominance hierarchies dominance hierarchies

Home Range

Florida scrub jay territories average 9 to 10 hectares, but are known to be as small as 5 hectares. The main limiting factor for territory size is habitat availability.

Communication and Perception

Florida scrub jays communicate using visual cues such as head bobbing; a movement used during territorial encounters. The complexity of their cooperation in defense, breeding, and hunting also suggests that intra-nest communication is important. They use vocalizations to exchange information and warn predators, such as the hiccup sound produced by female birds. Another example of this is the warning calls that these birds use to alert each other to the presence of predators.

• Communication Channels
• visual visual
• acoustic acoustic

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

Food Habits

These birds generally forage near the ground. They search for food by hopping along the ground. Acorns are the most important part of the diet, which they bury and cache for later use. Other nuts and fruits are also eaten. Florida scrub jays also eat insects, such as grasshoppers ( Orthoptera ) and butterflies and moths ( Lepidoptera ), bird eggs, and small vertebrates such as frogs, snakes, lizards, and mice. Some of these are Hyla cinerea , H. squirella , Anolis carolinenis , A. sagrei , Cnemidophorus sexlineatus , Coluber constrictor , Tantilla relicta relicta , Opheodrys aestivus , Mus musculus , Peromyscus gossypinus , P. polionotus , and Podomys floridanus . Foods offered by humans are also eaten as a supplement.

• Primary Diet
• omnivore omnivore

• Animal Foods
• mammals
• amphibians
• reptiles
• eggs
• insects
• terrestrial non-insect arthropods

• Plant Foods
• seeds, grains, and nuts
• fruit

• Foraging Behavior
• stores or caches food stores or caches food

Predation

Florida scrub jays defend themselves against predators by using lookouts to give warnings to other birds. They are social, alert, and aggressive and will actively mob predators. Scrub jays may be preyed on by predatory birds, such as hawks and falcons, or by domestic cats and bobcats.

Ecosystem Roles

Florida scrub jays play a role in maintaining population levels of insects and small vertebrates on which they feed. They also act as seed dispersers of scrub oaks ( Quercus species) by caching acorns. This species is also known to eat ticks from the backs of large mammals such as white-tailed deer ( Odocoileus virginianus ).

• Ecosystem Impact
• disperses seeds

Economic Importance for Humans: Positive

These birds are well-loved by bird watchers. They have beautiful bright blue colors and are active and vocal. They are important subjects for research on the evolution of cooperation.

• Positive Impacts
• ecotourism ecotourism
• research and education

Economic Importance for Humans: Negative

There are no known adverse effects of A. coerulescens on humans

Conservation Status

Overall numbers of A. coerulescens are declining mainly due to habitat loss, even though most of its remaining habitat is public land. In an effort to stop this habitat destruction, land is being set aside to be left in a natural state where fires clear the area and create a scrub habitat. Some land is being allocated to be burned at regular intervals, and only portions will be burned at a time. Also, to avoid satellite systems, where groups of birds are geographically isolated from the larger group, corridor connections are being made in Florida Scrub-Jay habitat.

Other Comments

Aphelocoma coerulescens once included scrub jays in California and Mexico as well, with the different populations identified as subspecies. Recently, this species has been revised so that A. coerulescens only includes Florida scrub jay populations. Other scrub jays are now A. californica , western scrub jays, and A. ultramarina , Mexican jays or gray-breasted jays. Island scrub jays, A. insularis , occur on Santa Cruz Island, off the coast of California. Taxonomic revisions were based on genetic and behavioral evidence. An example of behavioral evidence is that only Florida scrub jays use a cooperative breeding strategy.

Additional Links

Encyclopedia of Life

Contributors

Tanya Dewey (editor), Animal Diversity Web.

Eric Wohlford (author), Kalamazoo College, Ann Fraser (editor, instructor), Kalamazoo College.

References

Banks, R. 1983. "Obsolete English Names of North American Birds and their Modern Equivalents" (On-line). Accessed November 22, 2005 at http://www.pwrc.usgs.gov/infobase/obsnames/obsname2.pdf .

Bowman, R. 2003. Apparent Cooperative Hunting in Florida Scrub-Jays. The Wilson Bulletin , 115/2: 197-199.

Forbush, E. 1925. A Natural History of American Birds of Eastern and Central North America . New York: Bramhall House.

Garvin, J., J. Reynolds, S. Schoech. 2002. Conspecific Egg Predation by Florida Scrub-Jays. The Wilson Bulletin , 114/1: 136-139.

Schoech, S. 1998. Physiology of Helping in Florida Scrub-Jays. American Scientist , 86: 70-77.

Snyder, S. 1992. "Fire Effects Information System" (On-line). Aphelocoma coerullescens. Accessed November 19, 2005 at http://www.fs.fed.us/database/feis/wildlife/bird/apco/all.html .

Sullivan, J. 1994. "Quercus incana" (On-line). Fire Effects Information System. Accessed November 21, 2005 at http://72.14.203.104/search?q=cache:eIG5AokS-n8J:www.fs.fed.us/database/feis/plants/tree/queinc/all.html+florida+oak+scrub+elevation&hl=en .

1999. South Florida multi-species recovery plan . Atlanta, Georgia: U.S. Fish and Wildlife Service. Accessed November 19, 2005 at http://www.fws.gov/southeast/vbpdfs/species/birds/fsja.pdf .

2002. "National Audubon Society" (On-line). Florida Scrub-Jay. Accessed November 19, 2005 at http://audubon2.org/webapp/watchlist/viewSpecies.jsp?id=84 .

2001. "TAXONOMIC CHANGES AND THE BBS DATABASE" (On-line). U.S. Geological Survey. Accessed November 21, 2005 at http://72.14.203.104/search?q=cache:Dl0t3iDCbGkJ:www.pwrc.usgs.gov/bbs/bbsnews/AOUsplt1.htm+florida+scrub-jay+taxonomy+change&hl=en .