Predation of artificial nests in a fragmented landscape in the tropical
region of Los Tuxtlas, Mexico
Alejandro Estrada*, Andro
´
meda Rivera, Rosamond Coates-Estrada
Estacio
´
n de Biologı
´
a ‘‘Los Tuxtlas’’, Instituto de Biologı
´
a, Universidad Nacional Auto
´
noma de Me
´
xico,
Apdo 176, San Andre
´
s Tuxla, Veracruz, Mexico
Received 3 April 2001; received in revised form 27 July 2001; accepted 24 October 2001
Abstract
Predation rates of artificial nests were investigated in a fragmented landscape in the lowlands of Los Tuxtlas in southern Mexico.
Hen and plasticine eggs were used to assess predation pressure in four habitats: the interior of forest fragments, the forest–pasture
edge, corridors of residual forest vegetation and linear strips of live fences across pastures. Three sites per habitat were used in three
experimental trials. Hen and plasticine ground nests with three eggs each were alternated every 50 m along transects at each site.
Predation rates on each type of nest were monitored for 9 days. Survey of potential avian and mammalian potential nest predators
were conducted at each site prior to the experimental trails. Readings of amount of light illuminating the ground were taken by each
nest at each site to assess exposure of nests. In general, average predation rates were significantly higher for both hen and plasticine
nests in the forest–pasture edge and in the corridors than in the interior of the forest fragments. While birds and mammals were the
principal predators on hen eggs in the forests, mammals were responsible for the majority (570%) of eggs damaged at the other
habitats. Surveys of potential nest predators showed that avian and mammalian potential nest predators were significantly more
common at the forest–pasture edges and at the other habitats than in the forests. Readings of light reaching the ground suggest that
concealment of nests by the vegetation may play an important role in predation risk. Our results are consistent with reports from
other Neotropical rainforests indicating an increase of artificial nest predation pressures from forest interior to open habitats.
Restoration of forest fragments, allowing the vegetation to grow along the forest–pasture edge and the planting of arboreal crops at
the forest–pasture edges may be measures that could increase cover and nest protection. # 2002 Published by Elsevier Science Ltd.
Keywords: Forest fragmentation; Nest predation; Edge effects; Los Tuxtlas; Mexico; Neotropics; Conservation
1. Introduction
Forest fragmentation exposes the organisms that
remain in the fragment to the conditions of a different
surrounding ecosystem. Most of the resulting edge
effects seem to be deleterious to forest fragments by
causing changes in abiotic and biotic conditions (Mur-
cia, 1995; Laurance et al., 1997). Birds and other egg
laying animals may see their populations further dimin-
ished by high predation rates of nests in fragmented
landscapes (Zanette and Jenkins, 2000). Predation rates
of artificial nests are reported to be higher at forest
edges than in forest interior habitats (Moller, 1988;
Gibbs, 1991). Such patterns may result from increased
edge effects (Wilcove et al., 1986; Andre
´
n and Angel-
stam, 1988) or increase abundance of nest predators in
small forest patches (Terborgh and Winter, 1980; Karr,
1982; Andre
´
n 1992; Marini et al., 1995). Small forest
fragments contain more edge habitat than large frag-
ments which may result in low nesting success due to
high nest predation (Small and Hunter, 1988; Temple
and Cary, 1988; Hoover et al., 1995; Tellerı
´
a and Dı
´
az,
1995; Zanette and Jenkins, 2000).
Most studies of artificial nest predation have been
conducted in temperate forests and very few studies
have been reported for the tropics (Janzen, 1978; Loi-
selle and Hoppes, 1983; Gibbs, 1991; Tellerı
´
a and Dı
´
az,
1995; Latta et al., 1995; Wong et al., 1998). These stud-
ies showed that predation of nests seems to increase
0006-3207/02/$ - see front matter # 2002 Published by Elsevier Science Ltd.
PII: S0006-3207(01)00246-4
Biological Conservation 106 (2002) 199–209
www.elsevier.com/locate/biocon
* Corresponding author. Tel.: +52-294-30517; fax: +52-294-
24668.
E-mail address: aestrada@primatesmx.com (A. Estrada).