Roseate spoonbill

The roseate spoonbill is the only spoonbill native to the Western Hemisphere and is the only pink bird that breeds in Florida.

The Roseate Spoonbill (Platalea ajaja) is a medium-sized, pink-bodied, ibis-like bird with a flat spatula-shaped bill. They are found in the southeastern United States and West Indies through Mexico and Central America to South America. The roseate spoonbill is the only spoonbill native to the Western Hemisphere.

Roseate spoonbills feed by sweeping their spoon-shaped bills side to side, often sifting through mud as they walk through shallow water. Their diet includes small fishes and aquatic invertebrates, as well as some plant material. They are found in coastal marshes, lagoons, mudflats, and mangrove keys, foraging in both salt and freshwater. Flocks typically include fewer than half a dozen individuals.

Spoonbills reach maturity at approximately 16 weeks. Females typically lay two to five brown-speckled white eggs, which hatch after about 24 days. In about eight weeks, the young roseate spoonbills are ready to fly. Spoonbills can live up to 15 years in human care and an estimated 10 years in the wild.

Appearance

Roseate spoonbills have pink wings and underparts (with some red on the tops of the wings) with a white neck and back, and pinkish legs and feet. They can reach a length of 30-40 inches with a wingspan of 50-53 inches and weigh up to 4 pounds.

The pink coloration of spoonbill feathers is caused by an abundance of carotenoids, or algae pigments, present in the food the birds eat. As the spoonbill ages, the caroteniods accumulate from all of the aquatic animals it has eaten and the pink coloration becomes darker. No other Florida species is similar. The roseate spoonbill is the only spoonbill native to the Western Hemisphere and is the only pink bird that breeds in Florida.

Behavior

Roseate spoonbills forage using tacto-location to locate food while wading through shallow, muddy waters. In the early mornings and evenings, they slowly walk with their bill partially submerged, swinging it side to side, to sift out food from mud and water. The mandible contains nerve endings that snap the jaw shut as it contacts prey.

Catching prey by feeling, roseate spoonbills are able to forage without light, and thus their eye structure is not highly developed. Roseate spoonbills eat smaller prey. This includes fish such as minnows and killifish; crustaceans such as shrimp, crayfish, and crabs; aquatic insects; mollusks; slugs; and plant material such as roots and stems. If needed, roseate spoonbills may beat prey against a hard surface to aid in digestion .

Roseate spoonbills preen using their bill to nibble and run down the length of each feather, starting with their lower neck and down to their breast and abdomen. They clean their bill by dipping the tip in the water and then shaking their head to dry the bill.

Sleeping occurs communally with the roseate spoonbills standing on one leg, with their head turned backward underneath feathers in their upper back.

Members within a flock have been seen having a sham battle. This interaction does not harm either fighter, and it is unknown why this behavior is done. In the sham battle, two birds fly at each other, and may rise about a meter off the ground as they beat their wings.

When faced with a threat, roseate spoonbills alert conspecifics by standing tall with their neck outstretched and head held high. An alarm call may come in addition to this stance to call further attention to the threat. When fighting a threat, they hold the axis of their body parallel to the ground with their head lowered, neck outstretched, and wings raised above their body. Striking with their bill may result if the threat is intensified. One threat that causes this kind of behavior includes territorial defense against an encroaching member of an outside flock.

Only males have been seen to use defense mechanisms to defend a wide territory around his nesting site. Defense mechanisms may include a threat posture and chasing other spoonbills. Males will give up their territory rather than fight if threatened by other species. Females will only defend the actual nest.

Some displays are performed by the whole flock including up-flights and sky-gazing. Up-flights occur after the flock performs an erect posture and then flies up and circles around their territory. Sky-gazing occurs when another spoonbill is seen flying and individuals in the flock extend their neck and point their bill to the flying bird.

Mating

During courtship, the male and female first interact aggressively toward one another, but then proceed to perch close together with their bills crossed as the female begins to act submissively.

Courtship for roseate spoonbills involves ritualized exchanges of nest material such as sticks and twigs from the male to the female to attract her and help her build a deeply cupped nest in vegetation above a water source. Males may head-bob and shake the stick as they deliver nesting materials to a female. Females have been seen to beg for nesting materials with a bowing display.

They typically nest in mangroves or other trees and shrubs 5 to 15 feet above ground or water. The nest, a bulky platform of sticks with a deep twig, and leaf-lined center is built mainly by the female with material brought by the male.

Clutch size is 2 to 3 eggs, (range 1 to 5). The white eggs are spotted with brown. Eggs are incubated (by both sexes) for 22 to 24 days. Both parents feed the young. Young may leave the nest after 5 to 6 weeks and are capable of strong flight at around 7 to 8 weeks.

Distribution

The roseate spoonbill has an incredibly large distribution across the Americas, with its residential, or non-breeding, range spanning Argentina and Chile northward to the Texas Gulf Coast and Florida. There has never been a sighting outside of the Americas.

In the winter, U.S. populations are restricted to the southernmost regions of the Gulf Coast, primarily in south Florida, southwest Louisiana, and coastal Texas. In Florida, the species is found in Florida Bay, Tampa Bay, and Brevard County.

Although their range is poorly documented in South America, spoonbills are known to inhabit some portion of each South American country at some time of year. Unlike the spoonbills of the U.S., the spoonbills in South America tend to prefer living and nesting inland around freshwater. Some believe the South American populations are distinct from the resident populations in the USA and Central America.

As for breeding range, in the U.S., the roseate spoonbill breeds along the coasts of Texas, Louisiana, and southern Florida. Outside of the U.S., spoonbills only seem to breed along the coasts of Mexico and Central American countries, although this is not well documented. Little information on the spoonbills breeding range is available in Central and South America.

Habitat

Roseate spoonbills are aquatic wading birds with separate feeding and nesting habitats.

Feeding Habitat

Their preferred feeding habitat is shallow water with a muddy substrate bottom. Since spoonbills use their elongate bill to sift through the mud for food and their ability to lean in is dictated by their height, the water must be shallow for them to successfully forage. The spoonbills’ tarsus, or lower leg, is typically 4.2 to 4.8 inches long, meaning that their preferred water depth is equal to or less than 4.7 inches, on average. When absolutely necessary, spoonbills will occasionally feed in deeper water, where their breast feathers and heads are fully immersed.

Spoonbills do not seem to be directly affected by salinity and will forage in a variety of salt, brackish, and freshwater habitats.

Some specific locations include coastal bays, estuaries, lagoons, seagrass flats, marsh, tidal pools and mosquito control impoundments. One study in Florida found that spoonbills seem to prefer freshwater in some areas, which may be related to a limited ability to deal with hyperosmotic prey.

Nesting Habitat

In an attempt to stay far from potential disturbances and predators, Roseate spoonbills primarily nest and roost on islands, islets, or keys, in dense vegetation above ground or standing water. Although less preferable, spoonbills will also nest in shrub and forest wetlands on the mainland and occasionally in upland habitats farther inland.

Spoonbills do not require unique nesting habitat and will nest in mixed colonies with egrets, ibises, herons and other wading birds, so long as they are near suitable foraging habitat.

Roseate spoonbills construct their nests on shady horizontal branches, five to fifteen feet above ground or water. The highest spoonbill nest recorded measured 98 feet above the ground.

No specific vegetation is required, as spoonbills will construct their nests atop any low vegetation, trees, or shrubs with any plant material that is abundant in the nesting location or nearby shoreline.

Nesting Facts

Clutch Size:	1-5 eggs
Number of Broods:	1 brood
Egg Length:	2.2-2.8 in
Incubation Period:	22 days
Nestling Period:	35-42 days
Egg Description:	Whitish to pale green, evenly covered with brown spots.
Condition at Hatching:	Pink skinned and covered with white down. Eyed closed and unable to stand.

Threats

In the late 1800s, hunting for the feather trade decimated the roseate spoonbill population. The US Migratory Bird Treaty Act of 1918 was enacted, prohibiting the taking of roseate spoonbills, their eggs, and their nests.

Currently, roseate spoonbills are under least concern on the IUCN Red list with a stable population. Even though their population is stable, roseate spoonbills are suffering from habitat degradation and loss. Roseate spoonbills feed and nest in coastal marshes, lagoons, mudflats, and mangroves that are being highly altered from coastal development. Tourism in these newly developed areas further degrades the habitat of waterbird species.

Roseate spoonbills have been observed to stay away from high traffic areas, which may affect their migration routes and breeding sites. Analyzing hydrological processes, nesting distribution, and reproductive success is important when conserving the habitat for the roseate spoonbill.

Along with habitat loss, parasites are also a cause for concern to roseate spoonbill populations. In Southern Florida, 89% of roseate spoonbills examined were found to be infected with parasitic helminths. These parasites may come from their diet and lead to pathogens for roseate spoonbills. Texas roseate spoonbills are not infected by similar helminth species as the Florida individuals. One cause for this may be a difference in diet, resulting in different parasites being present. In Texas populations, nematode and cestode parasites have been found. The effects of these parasites is not well known but may lead to eggshell thinning, developmental issues, and an increase in disease.

As a result of polluted waters from increased development, the presence of mercury in roseate spoonbill livers has been observed. Increasingly polluted waters affect roseate spoonbills because it increases the concentration of contaminants such as mercury in fish species that constitute a large portion of their diet. Populations that eat larger fish accumulate a greater concentration of mercury in their systems due to biomagnification. Effects of mercury in wading birds include loss of motor skill, an increase in diseases, decreased immune function, embryo mortality, and alterations in behavior. Other toxins that may be of concern to the roseate spoonbill include cadmium, lead, and organochlorides.

Predators can threaten the roseate spoonbill population if there is an increase in predator density. Common predators to roseate spoonbills include humans, raccoons, fish crows, great-tailed grackles, and the red imported fire ant (Solenopsis invicta). Many of these predators attack the eggs and nestlings of waterbirds. To decrease the effects of predators on prey populations, monitoring the interaction and population of each species is necessary.

Some of these threats may worsen and lead to a susceptible roseate spoonbill population. In order to prevent this, systematic monitoring schemes, conservation sites, buffer zones, and water quality monitoring must continue.

Conservation and Management

Today, the roseate spoonbill is protected in the United States by the U.S. Migratory Bird Treaty Act of 1918 and in Florida as a State-designated Threatened species by Florida’s Endangered and Threatened Species Rule.

Perhaps the most important conservation problem for this species is the degradation and destruction of coastal foraging and nesting habitat.

Some of the human activities that put the roseate spoonbill population at risk include--recreational development, channelization of streams, creation of locks and dams, dredging, increasing boat traffic, draining wetlands, applying pesticide on agricultural land, and deforestation.

A major threat to roseate spoonbills is food availability, which is easily threatened by reduced freshwater inflow and hypersalinity exceeding the physiological tolerance of prey.

In addition to salinity issues, pesticides and other toxic contaminants such as organochlorides (DDT, DDD, dieldrin) and heavy metals (cadmium, lead), are harmful to both roseate spoonbills and their prey. With proper coastal water management, however, these last two threats are manageable.

Overall, some of the management practices necessary for maintaining preferable habitat for roseate spoonbills include--maintaining undisturbed/undeveloped areas, riparian habitat, and nature preserves; restricting human disturbance during migration, breeding, and nesting by creating no-access buffer zones; controlling pollution in aquatic habitats; protecting existing wetlands and restoring degraded wetlands; prohibiting hunting; and providing protection from predators like feral dogs and raccoons.

For now, the main goal should be the continual protection of the roseate spoonbill’s foraging and nesting habitat to ensure recruitment opportunities in the future. In order to properly manage the roseate spoonbill population, a few aspects of their biology need to be thoroughly investigated. Some areas of future research should include nesting and breeding ecology, diet and foraging ecology, demographic parameters, population genetics, and behavioral repertoire.

Images

Roseate Spoonbill in Merritt Island National Wildlife Refuge.

Roseate spoonbill (Platalea ajaja) wading in the Indian River Lagoon.

Roseate spoonbill in flight.

Roseate spoonbill foraging.

Roseate spoonbill nest.

Roseate spoonbill feeding at Merritt Island National Wildlife Refuge.

Roseate Spoonbill (Platalea ajaja) in the estuary

Weblinks

• Encyclopedia of life Roseate Spoonbill
• Florida Wildlife Conservation - Roseate Spoonbill
• FWS Darling National Wildlife Refuge - Roseate spoonbill
• Smithsonian National Zoo - Roseate spoonbill
• All About Birds - Roseate spoonbill
• National Park Service - Roseate Spoonbill
• Texas Parks and Wildlife - Roseate spoonbill
• Roseate Spoonbill in Tampa Bay
• Roseate Spoonbill Population Rebound
• Migratory Bird Treaty Act
• Florida Rule 68A-27 - Endangered or Threatened Species

Documents

• Florida Natural Areas Inventory - Roseate spoonbill (PDF, 2pp, 48KB)
• FWC - A Species Action Plan for Six Imperiled Wading Birds (PDF)
• Roseate Factsheet (PDF)
• Roseate spoonbill reproduction as an indicator for restoration of the Everglades and the Everglades estuaries. (PDF)

References