Puerto Rican Plain Pigeon Food Intake in a Captive Breeding Program I.I. Aviles-Vasquez & K. Aviles-Vasquez* *University of Michigan Residential College 124 Green, East Quad 1245 Ann Arbor, MI 48109 Puerto Rican Plain Pigeon at the aviary of the Puerto Rican Plain Pigeon Project, Humacao Campus of the University of Puerto Rico. Photo courtesy of Fr. Alejandro J. Sánchez Muñoz, Puerto Rico. Vol. 21 No. 4 2004 Endangered Species UPDATE 139 The Puerto Rican Plain Pigeon prickle (Zanthoxylum martinicense). (Columba inornata wetmorei) is one (USFWS 2004) of the endangered species in the is- Extensive destruction of natu- land of Puerto Rico. A captive ral forest habitat and overhunting breeding program was established are given as causes for the decline from 1984 to 2001 at the Univer- of the species. We can see this pat- sity of Puerto Rico (UPR) Humacao tern manifested in the development Campus as a way of combating the history of Puerto Rico. By 1912, decline of this species. The captive Puerto Rico had been largely breeding program in UPR cleared for agriculture and other Humacao had the objective of es- purposes with one estimate placing tablishing appropriate techniques the amount of remaining forest at for reproducing the species and no more than 5,000 acres of virgin produce individuals to be freed in or slightly-culled timber. By the the state forests. The captive pro- middle 1930s the plain pigeon gram has been successful in its use population was considered to be ex- of pigeon milk to feed the tinct, until, in 1963, a population hatchlings by a surrogate mother or was rediscovered in the town of by hand. This led to the successful Cidra, also following the pattern of breeding of 44 pigeons in 1989, a forest regrowth in the island. Stud- record in captive breeding pro- ies of that population between De- grams (Perez 2004). Despite the cember 1973 and September 1975 longevity and successes of the pro- attributed the majority of nest fail- gram, specifics for this particular ures observed to human-caused dis- race of plain pigeon are not well turbances. Habitat loss due to the known. For the first time in this rapid development of the Cidra study we measured the amount of area is the most serious threat to the feed that the pigeons consume in species’ existence. Though breeding captivity to determine their caloric occurs throughout the year, this intake and needs in case daily feeds species only lays one egg, and a are not available or illness arises in maximum of 3 broods has been re- an individual. corded. This contributes to de- The plain pigeon is the size of a creased population growth when its domestic pigeon with a pale blue- nesting areas are reduced every gray color, and dark red beak and year. Furthermore, it is thought legs. Historically, it was widespread that establishment of new popula- in the western foothills and valleys tions has been limited by the bird’s of Puerto Rico. General habitat reluctance to colonize new areas. types used include lowland swamps (USFWS 2004) and woodland, open woodland and For this study, the diet for the cultivated land in the mountains, captive individuals usually con- limestone karst, and coffee planta- sisted of grains, supplemented with tions in upland hills. The main day jasmine (Cestrum diurnum) source of food for the Plain Pigeon seeds, when in season. For the cap- are day jasmine seeds (Cestrum tive program, the amount of feed diurnum), but they also feed on was determined based on the esti- royal palm (Roystonea borinquena), mated protein and fat requirements mountain immortelle (Erythrina of the family Columbidae (Baer poeppigiana), West Indies trema 1984). However, such estimates are (Trema lamarckiana), and white not precise and despite of the lon- 140 Endangered Species UPDATE Vol. 21 No. 4 2004 gevity of the captive program, the erably smaller than the average for exact dietary requirements of the the Columbidae family (Perez 2004). plain pigeon and the effects of cap- Approximately one third of the pi- tivity on its feeding behaviors are geons would had no food intake for largely unknown. As the nature of days, despite readily available food, captive programs make daily and when they did eat, it was in feedings difficult, insights into di- very small quantities. On average, etary requirements of the plain pi- the older plain pigeons ate much geon are critical, not only to evalu- less than expected under normal ate the health of captive individu- conditions for Columbidae. als, but also to make necessary ad- Some possible reasons for these justments to avoid food deficits. results are 1. Plain pigeons in cap- Our objective was to determine tivity eat less than pigeons in the the average caloric intake of the wild because they don’t have to Puerto Rican plain pigeon in cap- spend energy on flying, looking for tivity. Each pigeon was kept in in- food, and/or mating rituals 2. Food dividual cages, and we chose 8 in- consumption of the pigeons de- dividuals for this study from the creases with age, and this was a smallest cages in the captive breed- likely factor in this study (pigeons ing project, due to ease of handling. on average were 10 years old). Fur- The daily feed for the captive plain ther studies are needed to deter- pigeons consisted of grains, con- mine if the effect of captivity, age, taining 15% protein, 2.5% fat, and or an interaction of these two fac- 10.5% fiber, well within the range tors caused the decrease in food in- of proteins (12-28%), and fat take of the captive individuals. Po- (1%) suggested by Dierenfeld tential future research may include (Dierenfeld and Kreger 1992). Each monitoring of wild individuals par- bird was given 45-55g of feed each allel to a similar set-up of this study morning in a marked cup. A small with younger actively breeding cap- carton box was placed under each tive individuals. Further research cage to collect the feed spilled dur- may help us to better understand ing the day. Unconsumed feed was and improve the health of the cap- collected from the cup and the car- tive individuals and the success of ton box and weighed each day be- the captive breeding program. tween 6 and 7pm to determine the Agradecimientos al ex-personal daily consumption of each of the del ex-aviario de Humacao y a birds (the original weight of feed Christian Espinoza-Pino. minus the weight of unconsumed feed). To determine the daily ca- Literature Cited loric intake the weight of feed con- Baer, David J. 1984. Animal Nutrition. To- ledo Zoological Society. sumed was then converted to a ca- Dierenfeld, E.S. y M.D. Kreger. 1992. Guía loric equivalent. This procedure Nutritiva y Dietética de los Animales was repeated each day of every Silvestres en Cautiverio. New York Zoo- other week from February through logical Society. Pp. 31-32 April in 2001. Pérez, Raul. 2004. Director, University of Puerto Rico Humacao Campus, Puerto We found that the captive Rico: personal communication. Puerto Rican plain pigeon con- U.S. Fish and Wildlife Service. Puerto sumes an average of 11.425 grams Rican Plain Pigeon. Species accounts. Di- of feed daily or 54.383 cal. This av- vision of Endangered Species. http:// endangered.fws.gov/i/b/sab40.html (ac- erage daily caloric intake is consid- cessed 1/Nov/04). Vol. 21 No. 4 2004 Endangered Species UPDATE 141.