Revista de Biología Tropical, ISSN: 2215-2075, Vol. 72: e53238, enero-diciembre 2024 (Publicado Feb. 29, 2024)
Impact of Collared Peccaries Dycotiles tajacu (Artiodactyla: Tayassuidae)
on understory vegetation in the tropical rainforest of
the Nogal-La Selva Biological Corridor, Costa Rica
Marco Herminio Osorto-Nuñez1*; https://orcid.org/0000-0003-2061-4950
Luis Diego Alfaro Alvarado2; https://orcid.org/0000-0001-9534-1948
Federico A. Chinchilla Romero3; https://orcid.org/0000-0001-5473-4307
Flávio H. Guimarães Rodrigues4; https://orcid.org/0000-0002-4797-0085
1. Instituto Internacional de Conservación y Manejo de Vida Silvestre. Universidad Nacional. Facultad de ciencias de la
Tierra y el Mar. Campus Omar Dengo, 40101, Provincia de Heredia, Heredia, Costa Rica; marco.osorto.nunez@est.una.
ac.cr (*Correspondence)
2. Facultad de Ciencias de la Tierra y el Mar, Escuela de Ciencias Ambientales, Universidad Nacional. Calle 9 y av. 1,
40101, Provincia de Heredia. Heredia, Costa Rica; luis.alfaro.alvarado@una.cr
3. Instituto Monteverde, Puntarenas, Costa Rica; federicoeap@gmail.com
4. Departamento de Genética, Ecologia e Evolução, Instituto de Ciências Biológicas, Universidade Federal de Minas
Gerais, Avenida Antônio Carlos 6627, Belo Horizonte, Minas Gerais, Brazil; rodriguesfhg@gmail.com
Received 15-VIII-2023. Corrected 20-II-2024. Accepted 22-II-2024.
Introduction: Evidence suggests that herbivores, such as peccaries, shape vegetation structure and diversity
through predation, trampling, dispersal, and rooting behavior.
Objective: To evaluate the impact of peccaries (Dycotiles tajacu) on the understory vegetation of the tropical
rainforest in the Nogal-La Selva Local Biological Corridor, Costa Rica, comparing a site with the absence of pec-
caries to another with the presence of these animals.
Methodology: From June to November 2021, 20 experimental exclusions and 20 free access plots, each measur-
ing 2 m2 were used to quantify herbivory, the number of leaf blades, damaged leaves, healthy leaves, sapling
height, and fallen biomass at both sites.
Results: A higher sapling density was found in the Nogal Reserve, but a lower sapling diversity, while in La Selva
there was a higher sapling diversity, but a lower density of seedlings. Herbivory and sapling height in La Selva
exceeded those in Nogal. The exclusion of peccaries reduced seedling damage but did not affect the dynamics
of fallen biomass.
Conclusion: For the design, implementation, and evaluation of the effectiveness of biological corridors, it is
crucial to consider plant-animal interactions to enhance the flow of ecological processes through functional and
structural connectivity, analyzed from interactions such as those presented in this paper.
Key words: Biological Station La Selva; herbivory; sapling height; natural regeneration; Nogal Reserve; Pecari
tajacu; recruitment.
https://doi.org/ 10.15517/rev.biol.trop..v72i1.53238
2Revista de Biología Tropical, ISSN: 2215-2075 Vol. 72: e53238, enero-diciembre 2024 (Publicado Feb. 29, 2024)
Herbivory, dispersion, and seed preda-
tion by wildlife species are vital processes in
forest ecosystems. These processes are a key
feature that may significantly influence sapling
establishment, growth, composition, and for-
est recovery (Feng et al., 2021; Genes & Dirzo,
2022; Neuschulz et al., 2016; Norden, 2014;
Vallejo-Marín et al., 2006). Herbivory is a cru-
cial ecological process that contributes to the
individual adaptation of species (Janzen, 1971).
Environmental variables such as temperature
fluctuations, humidity, and sunlight also can
also impact forest recovery, affecting various
trophic levels (Kuprewicz, 2013; Powell et al.,
2015; Yong et al., 2011).
Wild mammals play a key role in the
conservation of neotropical systems (Curran
& Webb, 2000; Hermes et al., 2006), as they
affect vegetation community diversity (Dirzo
& Miranda, 1991; Ickes et al., 2001; Mendoza &
Dirzo, 2007; Terborgh & Wright, 1994), through
predation of reproductive and vegetation com-
ponents, and recovery recruitment (DeMattia
et al., 2004). They facilitate modifications in
demography and plants composition in the
forest (Romero et al., 2016). Some findings sug-
gest that herbivores may become dominant in
trophic cascades (Borer et al., 2005). Neverthe-
less, analyzing the causes of mortality of sapling
is vital for understanding the processes that
maintain forest species diversity (Paine & Beck,
2007), since, besides herbivory, there are other
factors restricting the undergrowth sapling
recruitment. These factors include dispersion
restriction, environmental filters, biotic and
abiotic factors, and the negative density depen-
dence (Ramírez-Mejía & Mendoza, 2010).
Substantial evidence has been encoun-
tered, indicating that large herbivores such as
peccaries significantly contribute to physical
damage and mortality of undergrowth sapling
due to their rooting and trampling behaviors
while searching for fruits and seeds (Beck,
2005; Queenborough et al., 2012). However,
peccaries also contribute to the structure and
diversity of ecosystems and vegetation commu-
nities since they serve as seed dispensers and
predators (Beck, 2005; Beck et al., 2010; Clark
& Clark, 1989; Paine & Beck, 2007; Roldán
& Simonetti, 2001). Thus, relevance of wild
mammals in herbivory, such as peccaries, has
been acknowledged; disturbing their densities
Impacto del pecarí de collar, Dycotiles tajacu (Artiodactyla: Tayassuidae) en la vegetación del sotobosque
del bosque tropical húmedo del Corredor Biológico Local Nogal-La Selva, Costa Rica
Introducción: Existe evidencia que herbívoros, como los saínos, dan forma a la estructura y diversidad de la
vegetación a través del comportamiento de depredación, pisoteo, dispersión y enraizamiento.
Objetivo: Evaluar el impacto de los saínos (Dycotiles tajacu) en la vegetación del sotobosque del bosque tropical
húmedo en el Corredor Biológico Local Nogal-La Selva, Costa Rica, en un sitio con ausencia y en otro con pre-
sencia de saínos.
Métodos: De junio a noviembre de 2021 se utilizaron 20 exclusiones experimentales y 20 parcelas de acceso libre
de 2 m2, se cuantifico la herbivoría, número de láminas foliares, hojas dañadas, hojas sanas, altura de brinzales y
biomasa caída en ambos sitios.
Resultados: Se encontró una mayor densidad de brinzales en Reserva Nogal pero una menor diversidad, contra-
rio en La Selva donde se encontró una mayor diversidad de brinzales, pero una menor densidad de plántulas. La
herbivoría y la altura de brinzales en La Selva fue mayor que en Nogal. La exclusión de los saínos disminuyó el
daño a las plántulas, pero no afectó la dinámica de la biomasa caída.
Conclusión: Es necesario contemplar para el diseño, implementación y evaluación de la efectividad de corredores
biológicos, las interacciones planta-animal, para potencializar el flujo de procesos ecológicos mediante la conecti-
vidad funcional y estructural, analizada a partir de interacciones como las presentadas en este trabajo.
Palabras claves: Estación Biológica La Selva; herbivoría; altura de brinzales; regeneración natural; Reserva Nogal;
Pecari tajacu; reclutamiento.
Revista de Biología Tropical, ISSN: 2215-2075, Vol. 72: e53238, enero-diciembre 2024 (Publicado Feb. 29, 2024)
can have detrimental effects on the forest and
organisms that depend on litterfall and dendrit-
ic food webs (Beck, 2005; Reider et al., 2013).
On the other hand, peccary popula-
tions around La Selva Biological Station have
declined or become locally extinct (Kuprewicz,
2013). For instance, there are no reports of
peccary presence in the Nogal Private Wildlife
Refuge (Nogal) since 2004 by locals or based
on monitoring activities conducted by person-
nel of the reserve. Since 2004, wildlife tracking
has been conducted through field observation
and camera traps at the site, without sight-
ing any peccaries (pers. comm). In regard to
La Selva, studies on the historical and cur-
rent abundance of peccaries suggest population
growth (Kuprewicz, 2013; Michel et al., 2015;
Romero et al., 2013). Thus, comprehending the
role of this species in natural forest recovery is
essential, knowing that there is a possibility of
a significant reduction in its population in neo-
tropical areas (Beck, 2005; Gongora et al., 2011;
Ontiveros et al., 2021; Reider et al., 2013). This
reduction is attributable to rapid deforestation
rates and excessive hunting, which may impact
in the trophic cascade and the natural recovery
(Reider et al., 2013; Stoner et al., 2007).
Overall, recent studies have shown a ten-
dency of increasing peccary populations at La
Selva (Romero et al., 2013), leading to the per-
ception that peccaries are the source of nega-
tive impact on forest natural recovery (Michel
& Sherry, 2012). Based on this, a debate about
the management of this species at La Selva
has emerged (Romero et al., 2013). Investiga-
tions have focused on direct trophic relations
with one or more species in trophic cascades
(Michel et al., 2014), effects on insectivorous
birds and bats (Kalka et al., 2008; Van Bael &
Brawn, 2005), interaction and perturbation
between palms and peccaries (Avalos et al.,
2016; Queenborough et al., 2012), use of natu-
ral and anthropized areas (Osorto-Nuñez &
Alvarado, 2023) peccaries as important agents
that impact litterfall structure, and the abun-
dance of aquatic (anurans), and the terrestrial
reptiles (Beck et al., 2010; Reider et al., 2013).
However, few investigations have centered on
the direct relation of peccaries with recovery
dynamics and their influence in the tropical
forest at La Selva (Clark & Clark, 1989). Most
studies with mammals have been conducted
in other natural locations. (DeMattia et al.,
2004; Dirzo & Miranda, 1991; Ickes et al.,
2001; Mendoza & Dirzo, 2007; Paine & Beck,
2007; Roldán & Simonetti, 2001; Terborgh &
Wright, 1994).
Nevertheless, the presence of peccaries and
their relationship with the ecosystem should
not be considered negative a priori because its
natural distribution plays a crucial role within
the trophic chain or other ecological processes.
Therefore, efforts must be channeled to pre-
serve the integrity of mammal communities
and research the causes of sapling mortality to
better understand the processes that maintain
the diversity of forest species. In this way, we
can ensure the preservation of fauna and flora
and the ecological processes that favor the
recovery and maintenance at La Selva. Hence,
this study aims to measure the impact of pec-
caries (Dycotiles tajacu) on the understory veg-
etation of the tropical rainforest at the Nogal-La
Selva Biological Corridor, Costa Rica, in a site
without peccaries and another location with
their presence.
Study Areas: The study was conducted
within the biological corridor at Nogal-La
Selva, Heredia, Northwest Costa Rica. The
corridor was developed within the Natura-
leza y Communidad Project located in Nogal
(Masis-Aguilar, 2019; Ubieta et al., 2009).
It was created through collaborative efforts
involving Chiquita Brands, the local commu-
nity, the Sarapiquí local government, Rainfor-
est Alliance, German Technical Cooperation
Agency (GTZ), and the Swiss supermarket
chain Migros (Ubieta et al., 2009). Ecological
restoration actions took place from 2004 to the
present, aiming to connect the Nogal Private
Wildlife Refuge (Nogal) with La Selva Biologi-
cal Station (Masis-Aguilar, 2019). La Selva com-
prises an area of 1 600 hectares. It is classified
4Revista de Biología Tropical, ISSN: 2215-2075 Vol. 72: e53238, enero-diciembre 2024 (Publicado Feb. 29, 2024)
as a wet tropical rainforest (Hartshorn, 1983).
The average daytime temperatures range from
24.7 to 27.1 °C and receives between 3 800–4
000 mm of rainfall annually (Armstrong et
al., 2020; Robinson et al., 2018). The rainfall
is slightly lower from January to April (Clark
et al., 2013), while higher rainfall occurs from
June to July and from November to December
(Salazar-Blanco, 2001). La Selva is connected
with Braulio Carrillo National Park, featuring
primary rainforest, various stages of second
growth, and forestry systems (Arroyo-Arce et
al., 2013; Oviedo-Pérez, 2008; Raich et al., 2014;
Romero et al., 2013). It is located on volcanic
origin soil, which provokes an extreme of high
fertility of lowlands neotropical forests (Clark et
al., 2013) Fig. 1).
Meanwhile, Nogal, owned by Chiquita
Brand S.R.L, is in Puerto Viejo district, Sara-
piquí, Heredia, North Caribbean region of
Costa Rica (10°29’23’’ N & 83°56’15” W). This
reserve adjoins the Río Sucio to the North,
forming the Nogal-La Selva ecological corridor
(Masis-Aguilar, 2019). There are two areas of 92
hectares of wet rainforest and riverine habitat.
The reserve is mainly dominated by second-
growth forest and dense scrubland reed (Arun-
do donax), and it is 7.8 km away from La Selva
(Masis-Aguilar, 2019; Rodríguez-Matamoros
et al., 2012). The site falls within the tropical
rainforest life-zone (Holdridge, 1988) and has
a flat topography and elevations ranging from
40 to 51 m.a.s.l. The climate is predominantly
warm and humid, with temperatures fluctuat-
ing between 26 °C and 28 °C and an annual
rainfall of 4 000 mm (Masis-Aguilar, 2019)
(refer to Fig. 1).
Design of Exclosures and Control Plots:
La Selva served as the control site with the
presence of D. tajacu, while Nogal Refuge
was designated as the exclusion site without
Fig. 1. Location of experimental plots (exclosure and control) at La Selva Biological Station and Nogal Private Wildlife
Revista de Biología Tropical, ISSN: 2215-2075, Vol. 72: e53238, enero-diciembre 2024 (Publicado Feb. 29, 2024)
D. tajacu. In both areas, 20 paired plots of 2
x 2 meters were established, consisting of 10
exclosures treatments and 10 control treat-
ments with free access. Sampling periods were
conducted from June 9th, 2021, to January 31st,
2022. Before implementing the treatments, sev-
eral sampling areas were created to select the
precise site where plots were located. Polygons
were selected in Tres Ríos, Las Vegas, and
Arriera-Zompopa trails. Subsequently, random
points were created using QGIS 3.10 software,
considering 50 meters of separation distance
between plots to ensure the rain-induced seed
independence from the same parent tree, which
is significantly reduced after 50 meters (Ceccon
& Hernández, 2009; Cole et al., 2010; Martínez-
Ramos & Soto-Castro, 1993) (Fig. 2).
The paired treatments were separated by
a 5 m distance as shown in Fig. 3. Exclosure
treatments were surrounded by a galvanized
metallic mesh extending up to 1.10 m in height,
supported by stakes of flat iron rods with cor-
ners angled at 40 degrees. Plots had an opening
of 15 x 10 cm of wall base to allow the entrance
Fig. 2. Random points and points selected for exclosures and control plots in A. Nogal Private Wildlife Reserve and B. La
Selva Biological Station.