The Development of the Light-footed clapper rail Rallus longirostris levipes Recovery Program Laurie Conrad, Assistant Curator of Birds, SeaWorld California, 500 SeaWorld Dr. San Diego, CA 92109 email@example.com
Charles Gailband, Curator of Animals, Chula Vista Nature Center firstname.lastname@example.org
Dr. Richard Zembal, Natural Resources Director Orange County Water District, RZembal@ocwd.com
Michael Mace, Curator of Birds, San Diego Wild Animal Park, email@example.com
The Light-footed clapper rail Rallus longirostris levipes is one of the most endangered coastal birds in California. The population had declined to fewer than two hundred breeding pairs in the 1980s, primarily as a result of coastal wetlands destruction and degradation. The range of this sub species is from Santa Barbara to Imperial Beach, California in approximately twenty-three distinct locations.
Dr. Richard Zembal championed the plight of the Light-footed clapper rail and formed a coalition dedicated to the study and propagation of this species. U.S. Fish & Wildlife Service, Chula Vista Nature Center (CVNC), Sea World California (SWC), the San Diego Wild Animal Park (WAP), and independent biologists have partnered to develop a Captive Propagation Protocol.
The program has successfully bred both wild-captured rails and birds hand-reared from wild collected eggs and released them into the wild while developing a captive breeding protocol. Since 2001, both parent and artificial incubation/hand-rearing techniques have been used to fledge a total of 164 rails into nine distinct areas identified as rail habitat with depressed populations. Additionally, seven rails derived from the wild collected eggs were fostered by a captive breeding pair and released to the wild.
Telemetry was used to monitor the movements of some captive reared rails in 2005, 2006, and 2007 at four release sites. Preliminary telemetry studies have shown that the techniques used to rear the captive hatched clapper rails result in a bird that can survive after release.
Habitat restoration and captive breeding/release efforts have played an important role in the partial restoration of the Light-footed clapper rail. Educating the public about the bird’s plight and its connection to wetlands is also an important factor for the species survival. The Light-footed clapper rail recovery program has been committed to increasing public awareness about the plight of this endangered bird and saving North American wetlands.
MATERIALS AND METHODS
Eggs collected from the wild for artificial incubation are candled and/or floated in the field to determine fertility. The air cells of the eggs are marked in the field with a nontoxic Sharpie® marker. Eggs are collected from wild nests in Newport Bay and transported to SWC in a portable incubator set at 99.0 F (37.2C). Within the incubator the eggs are placed in a millet-filled container which is lined with foam to cushion the delicate eggs. Transport time is approximately 2 ½ hours. Upon arrival at SWC eggs are weighed, candled, and transferred to a Humidaire™ model 21 incubator. All eggs are candled using a Marsh Farm’s Hi-Intensity Candler to determine fertility and to check eggs for damage. Incubation parameters are 99.0 F (37.2C) dry bulb, 82-84 F (27.8 – 28.9 C) wet bulb. Eggs are manually turned, by hand, 180o, five times a day. Each egg is marked with an arrow on opposing sides, pointing opposite directions, to indicate the turning direction. This is important to prevent constant rotation in the same direction. Egg turning stops when the chick pips through the exterior egg shell. At this time the chick is moved into a Grumbach Hatcher. A hatching egg is placed on a bar mat lined tray with the air cell tilted slightly up. Pip to hatch interval is 24 - 48 hours. A clutch of healthy rail embryos should hatch synchronously, making it preferable to set all eggs from a clutch at the same time. Eggs are generally left with the female in the nest until transport for artificial incubation. Eggs are not stored as part of the management for this program. Rail chicks are precocial and begin walking within an hour of hatching. They hatch with their downy feathers matted to their skin. A newly hatched chick takes on a black and fluffy appearance within an hour. Chicks are moved from the hatcher to a brooder box at approximately 24 hours after hatching.
Housing & Rearing
The brooder box is 20” x 20” x 20” of wood construction. The box has screen vents that allow for light and air circulation. The heater is a porcelain based receptacle with a six watt red bulb and a thermostat. A second porcelain based bulb controlled by a toggle switch provides light. The light is switched on for roughly twelve hours each day. The brooder box surfaces are sealed with paint for ease of cleaning and disinfection. The box is lined with a clean towel free of holes or frays. Bar mat or shelf liner is placed on top of the towel as substrate for the small chicks. The shelf liner is changed out frequently during the day as needed. Rail chicks easily become tangled in loose threads so it is important to constantly check towels. Feather dusters are not recommended as brooders due to entanglement. The brooder box is cleaned and disinfected daily with an iodine based disinfectant such as Betadine or Pro Clean 200.
Tapes of ambient marsh sounds are continually played to minimize the potential for habituation to the sounds of keeper activity. Chicks are puppet reared in the brooder box until they are eating from a dish without stimulation. The chicks begin to pick at food dropped on the floor of the brooder by day two and puppet rearing is discontinued soon thereafter. At seven days of age, the chicks are moved to a heavily planted 4’ x 8’ enclosure with supplemental heat provided by a 250-watt ceramic core heater. The enclosure is screened with opaque plastic or screen to minimize human contact. The marsh sounds are played in this new enclosure and there is no talking in the area. Daily maintenance is limited to minimize exposure to animal care givers. By day ten the chicks eat live food items with ease and the base diet (commercial pellet items) is discontinued. At day 14 chicks are moved to an outside planted 4’ x 8’ enclosure with supplemental heat and a gently sloped pool. Supplemental heat is provided until the chicks are three weeks old and thermo-regulating in ambient temperatures. Diet
Rail chicks begin to eat almost immediately upon being moved to the brooder. The chicks are encouraged to eat independently by using a puppet head and forceps to tap at food. All feeding dishes are natural appearing artificial rocks. Mazuri Waterfowl Chick Starter ™, soaked dog food (Wayne’s Sensible Choice ™), hard-boiled egg yolk, are considered the base diet for newly hatched rail chicks. Fresh frozen fish (herring, capelin, whitebait, and silversides), krill, duckweed, and chopped romaine lettuce are also offered to the chicks. Live food items are placed on top of the base diet to stimulate interest in food and prevent the chicks from developing a preference for commercial diets. The live dietary components are varied on a daily basis. Readily available commercial components including crickets, mealworms, wax worms, bloodworms, pinkie mice, snails, and mosquito fish are fed because they are similar to natural prey items the rails would forage on in their natural habitat. Additionally, live organisms such as killifish, fiddler crabs, shore crabs, and isopods are collected from Sweetwater Marsh National Wildlife Refuge (SWMNWR) in Chula Vista, California, and fed to both hand-reared and parent-reared chicks as much as possible. Both natural and commercial live foods are important components of the diet because they provide stimulation and develop foraging behaviors that the birds will need for survival after release to the wild. Initially, diets are changed/ replenished ten times a day to prevent food spoilage. The interval between feedings and the volume fed increases and the number of feedings decreases as the chicks learns to forage. All food items are sprinkled with Vionate, a multivitamin, and calcium carbonate while chicks are fed previously frozen/thawed fish, krill and commercial pellet. Once sufficient foraging is identified in all members of a group (based on consecutive weight gains), the diet is transitioned to a live food only diet.
Transition for release
When the rail chicks are 90% hard-penned (after approximately 40 days) they are moved to a large transition enclosure in preparation for releases. The transition enclosures are built over a tidal slough on the SWMNWR at the CVNC. Enclosures are 75’ x 25’ and are heavily planted with native, inertial wetland plants. These enclosures provide an environment similar to the release habitat the birds spend 30 to 50 days in the conditioning enclosures before being released into the wild. Observers closely monitor the inexperienced birds from four to six hours a day, through a blind, to ensure each individual exhibits appropriate foraging and survival behaviors. Birds that fail to hide in the presence of native raptors are hazed by keepers and observers until they exhibit appropriate reactions. Diets at this stage consist largely of native, live prey items and commercial insects and fishes that are scattered randomly in to the enclosure to force foraging behaviors natural to the species.
Post-release Monitoring and Radio Telemetry
The Light-footed clapper rail is very elusive in its natural wetland habitat. The birds are so difficult to see in the wild that annual censuses are conducted by counting vocalizations as opposed to sightings. Each captive-bred rail is banded with a Federal (United States Fish and Wildlife) aluminum band and a colored leg marker. A variety of color markers have been used with varying degrees of effectiveness. The colored markers serve to denote the year of banding/release. Catching a glimpse of the colored band is difficult and identifying a rail by reading a band number is nearly impossible. This makes tracking released rails difficult. Radio telemetry was employed to monitor post release survivability and movements of captive reared rails in 2005, 2006 and 2007. Two different transmitter models have been used over the three years. In 2005, six gram transmitters were used with both tail mounts and a body harness for a handful of birds. In 2006 and 2007, one gram transmitters were used exclusively with tail mounts. The results were varied but the use of radio telemetry has confirmed that captive reared clapper rails can survive in the wild using the techniques currently employed.
Release sites are selected by Richard Zembal after the annual census is conducted. Resource management, food availability, vegetation, and existing rail populations are considered during the selection process. Zembal is the expert on the sustainability potential of habitat and Light-footed clapper rail behavior after over twenty years of study and data collection. Descriptions of all the marshes recently occupied by Light-footed clapper rails are available (U.S. Fish and Wildlife Service 1985). Artificial nest baskets designed by Zembal have been used successfully in rail habitat to provide suitable cover for rails in areas lacking sufficient vegetation. The baskets are a 2’ X 2’ piece of outdoor plywood covered with a dome of welded wire that is entwined and covered with raffia except for four side doors. The baskets were fixed 18 – 24 inches above the ground, beginning level with the vegetation canopy and proceeding above it, on two pieces of aluminum conduit driven securely into the substrate. Skinny bamboo rods were attached at various angles to and through the basket, protruding 36” in all directions above, to deter raptor perching. Continued efforts to provide enhanced cover, natural and artificial will, perhaps, make a positive difference over time.
Table 3. Number of Captive-reared Light-footed clapper rails Released into Target Marshes, 2001 – 2007.
The clapper rail has become a marquee species for all of the fauna that depend on coastal wetlands. CVNC, SWC, and the SDWAP have developed programs and educational opportunities to increase public awareness of the Light-footed clapper rail. CVNC exhibits the rail, allowing 60,000 to 80,000 guests a year to see the elusive, secretive bird up-close. SWC has brought the story of the Light-footed clapper rail in to the homes of millions of by featuring the rail and reintroduction efforts on their educational television series Shamu TV. SeaWorld and Busch Garden’s animal ambassador Julie Scardina has also featured in a segment of Jack Hanna’s Animal Wise highlighting the rail program. Another method used to create public awareness is the involvement of local volunteers for Light-footed clapper rail studies and reintroduction efforts. Animal Keepers at local zoological institutions have an opportunity to participate in field work including bird observations, habitat restoration, call counts, and nest checks with low transportation and logistical costs. The experience generates enthusiasm about the species and provides a greater insight into the natural history of the animal which has an impact on the knowledge and quality of care provided by the keepers. The program has incorporated local wetland community residents in a variety of activities like: censuses, artificial nest construction and maintenance, rail releases, and even radio telemetry tracking. Including citizens of nearby wetlands has resulted in increasing their sense of “ownership” of the resource and their willingness to be stewards and advocates for wetlands and the Light-footed clapper rail.
The annual counts from February until May are some of the best indicators of program success. A team of biologists study the calls of the rails to determine the number of pairs in more than thirty marsh habitats. In 2007 the California population of Light-footed clapper rails reached a population high for the fourth consecutive year. 443 pairs of rails were identified in 19 marshes. This is an increase from 218 pairs in 2001, the first year of the cooperative program. This is the largest number recorded since annual surveys were started in 1980. This former record high has now been exceeded in three consecutive years, 2004 – 2006. The population increase has been the result of rails management efforts, mainly the captive breeding/reintroduction activities, and major habitat restoration.
Although the propagation program has largely been a great success to date, survival has been poor for some early first clutches and broods. Early season egg and chick deaths appeared to be the results of exposure due to poor parental care during cold, wet conditions. One female in particular, ignored the chicks almost immediately and prepared to lay her next clutch. As a result, at least half and sometimes entire early first clutches have been pulled and artificially incubated to ensure higher survival. Nest success in captive breeding pens has increased by providing a heat source and/or cover. Nest failures due to predation from rats and a gopher snake in captive pens have had an impact on captive breeding despite predator abatement measures by some holding institutions. Nervous pairs have been documented destroying eggs.
The program has shown that the captive propagation and release of Light-footed clapper rails are a viable means to increase the genetic diversity and boost the wild population. The techniques for breeding and rearing Light-footed clapper rails are now being used by CVNC, SWC, and the WAP. Increased participation from other regional zoological institutions is being investigated for future program growth. However, a healthy Light-footed clapper rail population will not be based solely on the number of birds raised in captivity and returned to the wild. Wetland conservation and restoration are vital to the future of this coastal bird. There are currently important environmental measures in place to protect and restore coastal wetlands. However, these restoration efforts take time and will not be possible without support from the general public. The Clapper Rail and the importance of coastal wetlands have been incorporated into educational programs at the CVNV, SWC, and the SDWAP. A continued focus on education about coastal salt marsh preservation and the captive propagation and reintroduction of the Light-footed clapper rail will be important. Conservation measures and education are critical to ensure a healthy future for Light-footed clapper rails. This project is an example of the type work that can be done to benefit regional species and habitats while helping foster appreciation for local biological diversity. It is a reminder and example that zoological facilities can greatly benefit local conservation efforts. Further information can be found at www.clapperrail.com.
U.S. Fish and Wildlife Service. 1985. Recovery Plan for the Light-footed Clapper Rail. Portland, OR. 121pp.
Zembal, R., S. Hoffman, and J. Konecny. 2006. Statuses and Distribution of the Light-footed Clapper Rail in California, 2006. Report to CA Dept. Fish and Game, San Diego, CA. 16pp.
Zembal, R., S. Hoffman, C. Gailband, L. Conrad, and M. Mace. 2007. Light-Footed Clapper Rail Management, Study and Translocation in California, 2006. Report to CA Dept. Fish and Game, San Diego, CA. 30pp.
We thank Brian Collins, Jim Robins, and Lyann Comrack, for their leadership in the recovery program; Jim Kelly, John Konecny, Jim Robins for the many hours of searching for rail nests. Special acknowledgment goes to Susan Hoffman; the staff of the Chula Vista Nature Center, particularly Joyce Remp; the Sea World Avian Center team, particularly Richard Sardena and Dr. Judy St. Leger; the Fish and Wildlife Service; California Department of Fish and Game, particularly Lyann Comrack; the staff of the Wild Animal Park; and The Huntington Beach Wetlands Conservancy. These activities are conducted under Master Bird Banding Permit No. 22420, Federal Fish and Wildlife Permit No. TE839480-0, and a Scientific Collecting Permit and Memorandum of Understanding issued by the California Department of Fish and Game to Richard Zembal.
Newly hatched rail chick
Transition enclosure and observation blind
SeaWorld staff installing rail rafts for nests in the wild