The Everglade snail kite is a small raptor found exclusively in Florida. This endangered bird relies on apple snails as its primary food source and is therefore restricted to wetland habitats where these snails are found. Over the past several decades, loss of wetlands in Florida has caused major declines in Everglade snail kite numbers. Today, conservation efforts aim to protect and restore snail kite habitat in order to stabilize the remaining population.
What is the Everglade snail kite?
The Everglade snail kite (Rostrhamus sociabilis plumbeus) is a subspecies of snail kite found only in southern Florida. It is a medium-sized bird of prey, with adults reaching 12-15 inches in length and weighing around 10 ounces. Everglade snail kites have slate-gray plumage, long hooked bills adapted for extracting snails from their shells, and distinctive red eyes. They are specialized to hunt apple snails, which make up over 90% of their diet. Because of this extreme diet specialization, Everglade snail kites rely on wetlands with healthy apple snail populations in order to survive.
Everglade snail kites breed during the dry season from December to July. They build nests over stands of vegetation emerging from the water and lay 2-3 eggs per clutch. Both parents help incubate the eggs and feed the young once they hatch. After fledging, juvenile snail kites will remain with their parents for several months as they learn to hunt snails on their own.
Why are Everglade snail kites endangered?
Everglade snail kites are listed as an endangered species under the Endangered Species Act. This means the population is at risk of extinction throughout all or much of its range. There are several major reasons why Everglade snail kites have declined so severely since the early 1900s:
- Habitat loss – Draining of wetlands for agriculture and development has destroyed much of the snail kite’s habitat.
- Changes in hydrology – Constructing canals and levees has disrupted the natural water flows that recharge wetlands.
- Invasive plants – Non-native plants like hydrilla and water hyacinth displace native apple snail habitat.
- Environmental pollution – Runoff containing fertilizers, pesticides, and mercury harms apple snails.
- Droughts – Lack of rainfall dries up wetlands and reduces apple snail populations.
These threats have caused snail kite numbers to plummet from around 3000 birds in the 1960s to less than 1000 by the 1990s. Habitat loss is considered the primary reason for their endangered status today.
Habitat Loss
The Everglade snail kite relies on specific wetland habitats found only in southern Florida. These include the Everglades themselves as well as Lake Okeechobee, Upper St. Johns River basin, and other marsh systems. It is estimated that prior to drainage and development, there were over 8 million acres of snail kite habitat in Florida. Today, roughly 2 million acres remain.
Much of the wetland loss occurred in the early 20th century as swamps were converted to farmland. Canals and levees were constructed to control water flows. Lowered water levels led to invasion by woody plants, fires, and transition to drier upland habitats. More recently, continuing habitat destruction around major snail kite sites has further isolated and fragmented their range.
Hydrological Changes
Natural water flow patterns are critical to maintaining high quality snail kite habitat. Apple snails require shallow, consistently wet marshes with emergent vegetation. Disruption of seasonal flooding cycles and water drainage patterns degrades snail habitat. Construction of large canals and levees has greatly altered hydrology in the Everglades ecosystem. Diversion of water for agriculture and development also reduces water levels. Droughts in recent decades have compounded habitat damage from hydrological changes.
Invasive Species
Non-native plants have invaded many remaining Everglade snail kite wetlands. Two major invasive species are hydrilla and water hyacinth. These fast-growing plants form dense mats that crowd out native vegetation needed by apple snails. Chemical and mechanical efforts to control invasive plants have had limited success. Restoration of natural water flows may help reduce spread of invasives while favoring growth of native plants.
Pollution
Agricultural and residential runoff carries pollutants that can accumulate in wetlands, degrading habitat quality. Nutrient pollution from fertilizers promotes algae blooms and disrupts oxygen levels. Pesticides are also highly toxic to snails. Mercury accumulates up the food chain and can reduce snail kite reproduction. Development of treatment wetlands and limits on chemical use are needed to control sources of pollution.
How many Everglade snail kites are left today?
According to annual surveys conducted since 1972, the total Everglade snail kite population has ranged from around 500 to over 3000 birds. Numbers crashed dramatically during major droughts in the 1980s and early 2000s. Following these declines, population growth has rebounded during wetter years but not to historical levels.
The 2021 snail kite survey found 606 individual kites, up slightly from 592 in 2020 but below the 10-year average. For comparison, in 2000 near the end of a major drought, only 386 snail kites were observed. The highest count occurred in 2005 at 1394 birds.
While snail kites have maintained a population over 500 for two decades, their small overall numbers and fragmented distribution continue to pose a high risk of extinction. Most kites are restricted to just three sites – Lake Okeechobee, Water Conservation Area 3, and the Upper St. Johns River basin. A single severe drought, hurricane, or other disaster could decimate the remaining birds.
What is being done to help Everglade snail kites?
Efforts to stabilize and recover the endangered Everglade snail kite have focused on habitat protection, restoration, and management. Major initiatives aim to conserve wetlands, improve hydrology, and boost snail numbers across Florida:
Habitat Conservation
Government agencies and conservation groups have worked to secure protected status for remaining snail kite wetlands. Major sites have been designated as state wildlife management areas or acquired for projects like the Everglades National Park and Big Cypress National Preserve. Regulations limit development and habitat destruction within sensitive areas. Restoring wetlands on public and private lands around protected areas would help enlarge and connect snail kite habitat.
Hydrological Restoration
Fixing water flows disrupted by drainage and diversion is key for restoring healthy marshes. Plugging canals, removing levees, and rerouting water are all part of Everglades hydrology restoration. Allowing natural sheet flow and seasonal variations will boost apple snail reproduction and vegetation. Wetland water levels can also be adaptively managed via controlled releases from reservoirs.
Invasive Plant Control
Chemical, mechanical, and biological methods are used to reduce invasive marsh plants. Herbicide application and aquatic weed harvesters target individual plants while research explores using insects as biocontrol agents. Restoring natural hydrology to discourage non-native plants is likely the most effective long-term control strategy.
Snail Supplementation
Releasing captive-bred apple snails into managed wetlands has successfully boosted snail numbers where they were severely depleted. This provides a vital food source while habitat restoration matures. A central snail hatchery supplies juveniles to stock wetland areas, often before the breeding season. Snail supplementation has helped support higher snail kite populations during recent droughts compared to the 1980s.
Nest Monitoring
Tracking snail kite nests helps resource managers protect important breeding locations. Nests are located by airboat or helicopter surveys during the breeding season. Water levels can then be managed to prevent nest flooding or drying out. Nest access restrictions limit disturbances, and nest platforms have also been provided where vegetation is scarce.
Supplemental Feeding
Providing alternative food sources can help sustain snail kites when apple snails are scarce. Captive-bred snails and fresh meat have been placed on elevated platforms in key wetlands to provide access during low water. This strategy temporarily supported nesting kites during the 2015-2016 drought.
What is the outlook for Everglade snail kites?
The long-term outlook for Everglade snail kites remains uncertain due to their small population size, restricted habitat, and ongoing threats. Recovery goals aim to reach at least 2000 adult birds sustained across a wider range. Reaching this level would require restoration of over 1 million acres of wetlands and healthy snail populations. If current conservation targets are met, snail kites could potentially be downlisted to threatened status in the next decade.
However, habitat loss and degradation continue to outpace restoration efforts. Climate change poses additional risks from sea level rise reducing coastal wetlands and increased droughts that dry out marshes. Sustaining progress on hydrological repair, invasive plant control, and snail supplementation will be key. Expanding protected habitat areas and investing in major restoration projects focused on snail kite sites will help determine whether the species can recover.
Public education is also vital to build awareness of the snail kite’s imperiled status. Most Florida residents are unaware of this unique raptor and its role as an indicator of Everglades ecosystem health. Community wetland restoration efforts, citizen science monitoring, and engagement of policymakers can all aid snail kite conservation. While still critically endangered, targeted management paired with habitat restoration provides hope for the future of Everglade snail kites.
Conclusion
The specialized Everglade snail kite has faced catastrophic declines due to rapid Florida wetland destruction over the past century. Draining marshes for agriculture and development destroyed its habitat and degraded conditions through hydrological disruption, invasive plants, and pollution. From an estimated historical population around 3000, snail kites dropped to just a few hundred birds in the 1990s.
Conservation efforts have since focused on preserving and restoring key wetlands, managing water flows, boosting apple snail food sources, and monitoring nests. These initiatives have succeeded in boosting numbers to over 600 today, but the snail kite remains critically endangered. Expanding habitat protection areas and continuing ecosystem restoration projects focused on snail kite sites offer hope for recovery. Significant public engagement and long-term resources will be required to bring Everglade snail kites back from the brink.