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.

ABSTRACT

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

TERRESTRIAL ECOLOGY

2Revista de Biología Tropical, ISSN: 2215-2075 Vol. 72: e53238, enero-diciembre 2024 (Publicado Feb. 29, 2024)

INTRODUCTION

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

RESUMEN

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.

MATERIALS AND METHODS

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

Refuge.

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.