Engeman RM, Shwiff SA, Cano F, Constantin B
46 (2): 283-292 SEP 2003
The Puerto Rican parrot is one of the ten most endangered birds in the world, with the only wild population comprised of 30-40 birds. Predation has been identified as one of the factors limiting Puerto Rican parrot productivity in the wild, and the loss of a very few birds can have a great impact on the species. Management of red-tailed hawks, and black rats, feral cats and Indian mongooses, as well as further management of pearly-eyed thrashers is potentially beneficial to the parrot population. Because funding for the recovery of this rare species is finite, an analytical examination of the economics of predator management as a species enhancement method can provide managers with a solid basis for justifying and implementing this management approach.
We used a benefit-cost analysis (BCA) to examine the potential Pareto improvements of predator management for protecting Puerto Rican parrots. The median and minimum expenditures aimed at parrot reproduction for both captive and wild parrots from 1997 to 2001 were used to define monetary values for Puerto Rican parrots. Predator management costs were estimated from existing US Department of Agriculture/Wildlife Services (USDA/WS) contracts for similar work in Puerto Rico. We examined the benefit-cost ratios (BCRs) for predator management assuming one to five and ten parrots were saved by the efforts.
Analyses were conducted separately for each predator species and all species combined. The primary analyses focused on the benefits and costs for predator management for the current wild parrot population in the Caribbean National Forest (CNF), but another set of analyses targeted the proposed Rio Abajo (RA) site for the establishment of a second wild population. This second set of analyses was more conservative than for the existing population because predator management costs were assumed to be higher. Even when using the minimum monetary valuation for Puerto Rican parrots, the prevention of a single mortality due to predation within the existing wild population results in monetary benefits slightly exceeding the combined costs for management of each predator species (BCR = 1.01). If median parrot values are applied, then only one parrot saved every 2.6 years allows the combined predator management to be cost-effective.
If the year of maximal parrot values (averaged over captive and wild populations) is used, then only one parrot saved every 4.2 years makes application of all predator management methods cost-effective. Use of the single highest per-parrot value from among years and populations would result in the combined application of all forms of predator management being cost-effective if only one parrot is preserved from predation every 11.8 years.
Assuming higher costs and minimum parrot values results in the combined application of predator management at the RA proposed population site to be cost-effective if 1.8 parrots/year are saved from predation. Use of median parrot value allows predation management to be cost-effective if one parrot is saved every 1.4 years. If actual costs for the RA site are the same as for the CNF, then the BCRs improve correspondingly. As more parrots are saved, the BCRs increase dramatically for each site. Published by Elsevier B.V.
benefit-cost analysis, benefit-cost ratios endangered species, predation management
Engeman RM, Natl Wildlife Res Ctr, 4101 LaPorte Ave, Ft Collins, CO 80521 USA
Natl Wildlife Res Ctr, Ft Collins, CO 80521 USA
Caribbean Natl Forest Catalina Work Ctr, Palmer, PR 00721 USA
USDA, APHIS, WS, Gainesville, FL 32641 USA
ELSEVIER SCIENCE BV, PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS