General Biology

The Order Ciconiiformes comprises medium- to large-sized, charismatic wading birds that are popular in zoologic collections. This group has a worldwide distribution in temperate, subtropical, and tropical climates. The five families include Ardeidae (herons, bitterns, and egrets), Balaenicipitidae (shoebills), Ciconiidae (storks), Scopidae (hammerkopfs), and Threskiornithidae (ibises and spoonbills).^11,24 Over 26 species are considered near threatened, vulnerable, or endangered by the International Union for the Conservation of Nature.³⁰ Many species are long lived, with some of the larger species living for 40 to 50 years.⁸

Most species are sexually monomorphic with similar feathering; however, females are usually smaller than males. Gender determination may be accomplished through DNA (deoxyribonucleic acid) analysis of whole blood or blood feathers. Other techniques, which have proved successful, include measurements of bill length, tibiotarsal length, and body length.^51,68,70

Unique Anatomy

Most Ciconiiformes species have long legs and elongated toes with slightly webbed feet. The middle toe may be well developed for feather maintenance. Most have long necks with 15 to 20 vertebrae. Herons have a modified sixth cervical vertebra, which allows the neck to be held in an S-shape during flight. Many species have bare portions to the head and neck. Herons have powder-down feathers; however, adult storks, ibises, and spoonbills lack this feature.

Storks lack syringeal musculature, and most are mute. Bill clattering is an important form of communication, especially in Ciconiidae. Openbill storks have a distinct separation between their rhamphotheca and gnathotheca, whereas the other stork species have variably tapered long beaks.¹⁸

Special Housing Requirements

In a captive environment, meeting the physical, social, and psychological needs of the species through appropriate exhibits, social groupings, and opportunities to express species-appropriate behaviors will maximize their welfare. Large meshed exhibits, which allow uninterrupted flight, are most ideal. Where this is not possible, feather clipping may be performed to keep birds in open exhibits. Pinioning is not recommended, as it potentially interferes with breeding ability and may violate legal regulations in some countries. A water feature such as a pond or small lake should be available. Natural substrate with low, wide stumps is preferred, and trees should be available for perching. Many zoologic facilities successfully display various Ciconiiformes species in mixed-species exhibits; however, care should be taken because interspecific aggression–related trauma has been documented. When these birds are housed with larger species, a safety zone should be established that allows the birds ability to enter while preventing access by the larger species.

Feeding

Most Ciconiiformes species are aquatic carnivores, and fish, amphibians, aquatic insects, molluscs, small mammals, birds, and reptiles are part of the diet in the wild; however, not all species feed on all of these. Some are generalists, whereas others are specialists. For example, openbill storks feed on freshwater snails (Pilia spp.) and bivalve mollusks almost exclusively. Adjutant storks are part-time scavengers at kills of large predators; however, they feed their young only live-caught prey. Some ibises hunt for insects in grasslands. Spoonbills have large, flat, spatulate bills and feed by wading through shallow water, sweeping the partly opened bill from side to side. The moment any small aquatic creature—an insect, crustacean, or tiny fish—touches the inside of the bill, it is snapped shut.^10,18

In a captive environment, Ciconiiformes species are fed a variety of fish, whole vertebrate prey (e.g., rodents, juvenile rabbits, day-old chicks, and amphibians), nutritionally balanced ground-meat carnivore products, insects, earthworms, and commercially prepared carnivore and avian dry and semi-dry pelleted diets. As in other carnivore species, it is important to avoid excessive amounts of vitamin A in the diet. Chicks are fed regurgitated food, so appropriate food sizes are important. For growing chicks, it is important to supplement the diet with calcium (e.g., bone meal, calcium lactate) and to ensure that they have access to dietary sources of vitamin D (as found in whole prey food items) and exposure to natural or artificial ultraviolet B (UVB) light. Where fish is a predominant portion of the diet, it is essential to supplement with vitamin E and thiamine to offset the peroxidation and thiaminase activity in frozen fish.^18,69 Roseate spoonbill and scarlet ibis require supplementation with special pigments (synthetic canthaxanthin) in their diet so that they can exhibit normal natural brilliant feather and skin coloration similar to flamingos. In the wild, they obtain these pigments from feeding on aquatic invertebrates. Newly hatched chicks of these species will lack pigment.

Restraint and Handling

Appropriate planning should take place prior to capture or immobilization. Capture myopathy is not uncommon in Ciconiiformes. Care should be taken when handling and restraining to prevent injury to the bird and to the handler. Ensuring that an appropriate number of people are present is paramount, particularly with larger birds. Birds may be initially netted, or herded into a smaller space, for hand capture. The long legs and the beak should be controlled to prevent trauma. Personal protective equipment such as safety glasses or face shields is recommended, particularly with aggressive individuals. Some handlers place a large syringe case or a similar apparatus over the beak as an additional safety measure for species with sharp-tipped bills.

Anesthetic techniques are similar to those used for other large avian species. To accommodate the large bill, anesthetic masks often need to be fabricated from plastic syringe cases, bottles, cones, obstetric gloves, or sheets of rubber. Induction and maintenance with gaseous anesthetics (isoflurane or sevoflurane) in oxygen at appropriate flow rates is most commonly used for anesthesia. Intubation is typically straightforward; however, it should be performed with utmost care to minimize trauma and resultant inflammation, as postintubation tracheal granulomatous obstruction has been reported in some species of Ciconiiformes.^48,64 Many of the Ciconiiformes species have a crista ventralis in the center of the glottis, which may make intubation a bit more challenging. Induction with an intravenous (IV) agent such as propofol (5–7 milligrams per kilogram [mg/kg] to effect) is also effective. Where gaseous anesthesia is not possible, a combination of intramuscular (IM) medetomidine (0.1 mg/kg), ketamine (5–10 mg/kg), and midazolam (0.1 mg/kg) has proven successful for immobilization in larger stork species and would likely work well in other Ciconiiformes species. While the bird is under anesthesia, monitoring of end tidal carbon dioxide is strongly recommended, as ventilation may be affected by patient positioning and significant dead space may exist in the long trachea and air sacs. Intermittent positive pressure ventilation during anesthesia is successful in reducing hypercapnea. During recovery from anesthesia, the bird should be held or semi-confined (e.g., in a padded crate) until it is capable of standing to prevent injury. It is best to avoid keeping the legs in one position for the entire procedure or surgery.

Surgery (Common and Special Considerations)

Traumatic injury, either self-inflicted or from intraspecies or interspecies aggression, is the most frequent cause for surgery encountered in a captive setting. Techniques used in other avian species are applicable. The novel use of hinged braces as an external support device for soft tissue joint injuries has been described in storks.³⁶ Beak prosthetics have also been used successfully. In northern climates, ischemic necrosis from frostbite may necessitate amputation when medical management is not successful. Necrosis of the cervical throat sac was documented in a marabou stork that was managed successfully with surgical resection and supportive care (Donna Todd, personal communication, 2011).

Postintubation tracheal obstruction has been reported in storks and often requires surgical management via tracheal resection and anastomosis or laser ablation.^48,64

Multimodal analgesia is an important component of surgical management. Pharmacokinetic and clinical efficacy studies of analgesics have not been published for any Ciconiiformes species, so extrapolation is made from other avian species. Local anesthetics (lidocaine 1 mg/kg, bupivacaine 1 mg/kg), meloxicam (0.3–0.5 mg/kg, IM, once daily [SID]), and the opioid butorphanol (0.5–1.0 mg/kg, IM, every 4–6 hours [q4-6h]) have been used successfully by the authors of this chapter.

Other Pharmaceuticals

No published studies of pharmacokinetics or clinical efficacy exist for Ciconiiformes species. Extrapolation for drug dosages is based on published studies and experience with other avian species. Fenbendazole toxicity has been reported in marabou storks at a dosage of 60 mg/kg, so caution is advised when using this anthelmintic in Ciconiiformes.⁶

Physical Examination and Diagnostics

A systematic approach to the physical examination should always be followed. Ciconiiformes may be safely physically restrained for the examination.

Specimen collection and handling are the same as in other avian species. Venipuncture may be accomplished from the jugular vein, the medial metatarsal vein, or the ulnar vein. As many storks will defecate and urinate on their legs to keep cool, it is important to clean the metatarsus prior to blood collection to avoid false elevations in uric acid.

Erythrocyte morphology and hematologic and serum biochemistry parameters have been studied in juveniles and adults of several Ciconiiformes species.^{1,2,9,12,16,28,31,39,55,57,58,65} The hematocrit, the erythrocyte count, and the hemoglobin concentration increase from hatching to adulthood, and this is thought to be related to oxygen demands for flight.^2,55 Gender- and age-related alterations to serum biochemical values have been noted, especially in total protein, albumin, uric acid, cholesterol, and aspartate aminotransferase.^31,39 The interpretation of hematologic and serum biochemical values is similar to that in other avian species. Spoonbills and scarlet ibises have pink plasma, which should not be confused with hemolysis. Reference ranges for species held in captivity are available from the International Species Information System (www.isis.org).