Mysterious disappearances of a large mammal in Neotropical forests

Abstract

SummaryThe drivers of periodic population cycling by some animal species in northern systems remain unresolved1. Mysterious disappearances of populations of the Neotropical, herdforming white-lipped peccary (Tayassu pecari, henceforth “WLP”) have been anecdotally documented and explained as local events resulting from migratory movements or overhunting2,3,4, or as disease outbreaks5,6, and have not been considered in the context of large-scale species-specific population dynamics. Here we present evidence that WLP disappearances represent troughs in population cycles that occur with regular periodicity and are synchronized at regional and perhaps continent-wide spatial scales. Analysis of 43 disappearance events and 88 years of commercial and subsistence harvesting data reveals boom – bust population cycles lasting from 20 to 30 years, in which a rapid population crash occurring over 1 to 5 years is followed by a period of absence of 7 to12 years and then a slow growth phase. Overhunting alone cannot explain the crashes, but as in northern systems dispersal during the growth phase appears to play a key role. This is the first documentation of population cycling in a tropical vertebrate.

Disappearance of an ecosystem engineer, the white-lipped peccary (Tayassu pecari), leads to density compensation and ecological release

“…2 A). These patterns are consistent with the proposed crash event periods described by Fragoso et al ( 2020 ) based on the ratio of white-lipped peccary to collared peccary in the southwestern Amazon (recreated in Fig. 2 B).…”

“…2 A Mean and 95% credible intervals of the predicted habitat use for WLP in the pre-crash (2005/2006, purple and circles) and post-crash (2019, orange and triangles) periods, and between two major habitat types; terra firma and floodplain. B Focal camera trapping periods overlayed on the hunting off-take data from the region—adapted from Mysterious disappearances of a large mammal in Neotropical forests (Fragoso et al 2020 ) …”

“…White-lipped peccary ( Tayassu pecari —WLP herein), a species of conservation concern, has been extirpated in 21% of its range over the past century, with reduced abundance and a low to medium probability of long-term survival in 48% of their current range (Altrichter et al 2012 ; Richard-Hansen et al 2014 ; Fragoso et al 2020 ). This has been attributed in some cases to localised population reduction or extirpation due to hunting (Reyna-Hurtado 2009 ; Reyna-Hurtado et al 2010 ), habitat loss, and fragmentation (Keuroghlian et al 2015 ).…”

“…This has been attributed in some cases to localised population reduction or extirpation due to hunting (Reyna-Hurtado 2009 ; Reyna-Hurtado et al 2010 ), habitat loss, and fragmentation (Keuroghlian et al 2015 ). However, recent evidence also suggests that population boom-bust cycles occur across wide regions, and potentially, even biomes (Richard-Hansen et al 2014 ; Fragoso et al 2020 ). Such boom-bust dynamics have been speculatively attributed to epidemic outbreaks and associated rapid mass die-offs, likely tied to WLP’s tendency to form mega-herds, a unique social structure for a Neotropical mammal (Fragoso 2004 ).…”

“…To explore the implications of a single species disappearance on the wider vertebrate community composition, we take advantage of a fortuitous natural experiment using camera traps to quantify habitat-use prior to (2006–2007) and post (2019) a widespread population crash in WLP, which occurred around 2010 (Fragoso et al 2020 ). To achieve this, we use a temporally replicated camera trapping dataset to examine the effects of WLP disappearance on the terrestrial, medium-large vertebrate community structure within the Los Amigos Conservation Concession (LACC).…”