You are not currently logged in.
Access your personal account or get JSTOR access through your library or other institution:
Predicting Early Mortality of Newborn Guanacos by Birth Mass and Hematological Parameters: A Provisional Model
Laura L. Gustafson, William L. Franklin, Ronald J. Sarno, Russel L. Hunter, Karen M. Young, Warren E. Johnson and Michael J. Behl
The Journal of Wildlife Management
Vol. 62, No. 1 (Jan., 1998), pp. 24-35
Stable URL: http://www.jstor.org/stable/3802261
Page Count: 12
Preview not available
We measured hematological determinants, endocrine parameters, and birth mass of 145 newborn (chulengo) guanacos (Lama guanicoe) in Torres del Paine National Park, Chile, to determine if these factors were predictors of early mortality. Within 10 days of life, 16% of chulengos died in 1991 and 14% died in 1992. The principal cause (68%) of chulengo mortality was predation by the Patagonian puma (Felis concolor patagonia), but the role of compromised health was unknown. We assessed the health status of hand-captured chulengos by measuring white blood cell (WBC) count, differential leukocyte count, neutrophil:lymphocyte ratio (N:L), metarubricyte count, cortisol levels, total T3 and T4, and birth mass. We evaluated the prognostic relation of these parameters on neonatal mortality through Chi-square and Bayesian analyses. Band neutrophil count >1000/μL, lymphocyte count >4000/μL, N:L ratio <2, metarubricyte count >300/μL, and birth mass <10 kg categorized the nonsurvivor group more than the survivor group. A Bayesian model using band neutrophil count and N:L ratio labeled 9% of the newborns as "unhealthy," and correctly predicted 44% of the mortalities and 96% of the survivors. Variations between cohorts suggested that a low N:L ratio (possible prematurity) and metarubricytosis were more common in 1991, but that sepsis was more important in 1992. Within the category of correctly predicted mortalities, none (0/3) of the carcasses of animals with band counts >1000/μL (suggestive of sepsis) showed signs of puma predation, while 100% (4/4) with an N:L ratio <2.0 (possible prematurity) showed signs of puma predation. The hematological parameters showing the strongest relation with mortality were also some of the least expensive and easiest parameters to measure. Readers should consider this Bayesian model groundwork for future studies assessing health-related neonatal mortality in guanacos. The approach also has research and management implications for other wildlife species.
The Journal of Wildlife Management © 1998 Wiley