Alice Roy‐Bolduc Justine Alexander Guillaume Peterson‐St Laurent
Internship Report: Observations on the Ecology and Behavior of Saguinus geoffroyi and Aotus zonalis in a Semi Humid forest located in Charges National park.
Under the Supervision of Rafael Samudio and MaribelTejada
Presented to Rafael Samudio and Keisha Kerr Envr 451‐ Research in Panama McGill University April 24th, 2009
Observations on the Ecology and Behavior of Saguinus geoffroyi and Aotus zonalis in a Semi Humid forest located in Charges National park.
Authors: Alice Roy‐Bolduc (School of Environment, McGill University) Justine Alexander (Department of Biology, McGill University) Guillaume Peterson‐St Laurent (School of Environment, McGill University)
Supervision: Rafael Samudio, Jr. Ph.D. Presidente de SOMASPA and director of the Programa de Biodiversidad de Mamíferos [email protected] MaribelTejada Licenciada en Biología
Number of full days dedicated to the project (1 full day = 8 hours) In the field: 12,31 Not in the field: 7,16
April 2009 Cover: Danylo Bobyck
2
ABSTRACT
The destruction of Neotropical forests disturbs and puts the livelihood of many species in Panama at great risk. Arboreal neotropical primates are particularly threatened by habitat conversion. The presence of primates in Panama has important economic and cultural significance and is essential for the functioning of ecosystems. Action should therefore be taken in order to protect primates. More information on primate species could help facilitate conservation practices. The objective of this project was to gather and evaluate data on two primate species which are currently understudied, the Panamanian night monkey (Aotus zonalis) and Geoffroy’s tamarin (Saguinus geoffroyi). ln addition, we realized a brochure on the ecology and conservation of primates in Alto Chagres conservation area and Panama. The investigation was carried out in Campo Chagres, a site located within the conservation area of Alto Chagres, Panama. The site consists of a lowland semi‐deciduous forest with areas of dry forest and young moist tropical forest. Despite protective efforts by ANAM, the area is marked by important human disturbances. The study took place during the dry season (January to April 2009). Four transects, totalling 7,2 km, were established in Campo Chagres along pre existing paths. These transects were surveyed by two or three observers for both primate species at different times. Observations for Saguinus geoffroyi took place during the day and observations for Aotus zonalis took place during the night. When a group was encountered, data regarding the animals and habitat were gathered. Information on troop size and composition, behaviour, habitat use, interaction with other animals and the presence of predominant tree species vegetation were recorded. To obtain more precise data on the troop composition and individuals’ behaviour, the observers could leave the transect line. After the 4 months of field study, 64.65 km of transects in total were travelled and nine different groups of Geoffroy’s tamarin were localized and observed. No Panamanian night monkey was sighted. The areas where the Geoffroy tamarin was localized are characterized by predominantly dry semi‐deciduous vegetation. Tamarin abundance in Campo Chagres was found to be 0.2 groups per km, which is fairly similar to results of other studies done in Chagres national park. Groups ranged on average between three to seven individuals. An analysis of their activity indicated that travelling was by far the most important activity accomplished. The primates were also continually communicating vocally with birdlike squeals and whistles. Since the study was carried out during the dry season, there was an absence of food sources in Campo Chagres. The fact that Geoffroy’s tamarin was successfully observed suggests that there is a difference in the ecology and behaviour of the two primate species. We hypothesized that the night monkeys migrated to richer more elevated and humid regions of Chagres National Park. In conclusion, this investigation highlights the need to consider migration patterns and various scales in the assessment of population abundance and distribution in a dynamic tropical forest. This is essential in order to develop adequate conservation strategies.
3
RESUMEN
La destrucción de los bosques Neotropicales perturba y pone en peligro el sustento de muchas especies de Panamá. La conversión de hábitat pone particularmente los primates arbóreos Neotropicales en peligro. La presencia de primates in Panamá tiene una importancia cultural y económica y es también esencial para mantener el funcionamiento del ecosistema. Entonces, acción debe ser entrepernada para proteger primates. Más información sobre las especies de primates podría ayudar a mejorar las prácticas de conservación. El objetivo de este proyecto fue de reclutar y evaluar los datos sobre dos especies de primate que son actualmente “understudied”, el mono titi (Saguinus geoffroyi) y el mono nocturno (Aotus zonalis). Además, realizamos un folleto sobre la ecología y la conservación de primates en la zona protegida del Alto Chagres y de Panamá. La investigación sucedió en Campo Chagres, un sitio ubicado en la zona protegida de Alto Chagres, Panamá. Campo Chagres es une zona de tierras bajas cubierto de un bosque semicaducifolio joven donde se encontra un mosaico de vegetación seca y húmeda. Aunque es una área protegida por ANAM, este sitio esta bastante perturbado por actividades humanes. El estudio se realizó en Panamá durante la temporada seca (enero abril 2009). 5 transectos fueron establecidos en Campo Chagres por senderos que ya existían. Estos transectos fueron inspeccionados por dos o tres observadores para estudiar los dos especies de primate en tiempos diferentes. Las observaciones del mono titi sucedieron durante el día y observaciones del mono nocturnos sucedieron durante la noche. Cuándo un grupo fue encontrado, los datos con respecto a los animales y el hábitat fueron registrados. Para obtener datos más precisos sobre la composición de tropa y del comportamiento de los individuos, los observadores dejaron la línea de transecto. Después de los 4 meses de estudio de campo, 64,65 Km. de transectos fueron viajados y 9 grupos diferentes de mono titi fueron localizados y observados. Ningún mono nocturno fue observado. Las áreas donde el mono titi fue situado fueron caracterizadas por un bosque bastante seco con una vegetación media caducifolia. La abundancia de mono titi en Campo Chagres fue calculada a 0,2 grupos por km. Este es bastante similar a resultados de otros estudios hechos en áreas del parque nacional Chagres. Los grupos recorrieron en el promedio entre 3‐7 individuos. Una análisis de su patrón de actividades indicó que el movimiento fue de lejos el más importante de las actividades realizada. También, los mono titi estaban continuamente comunicando con chillidos y silbidos parecido a sonidos de aves. El estudio fue llevado durante la temporada seca, entonces había una ausencia de alimentos en Campo Chagres. El hecho que el mono titi fue observado exitosamente soporta que haya una diferencia en la ecología y el comportamiento de las dos especies de primate. Formamos una hipótesis que el mono nocturno emigró a otras regiones más húmedas en el Parque Nacional Chagres. En conclusión, esta investigación revela la necesidad de considerar varios escalas y patrones de migración en la evaluación de la abundancia y distribución de
4
populaciones animales en un sistema tan dinámico con el bosque tropical. Eso es esencial para el desarrollo de estrategias de conservación adecuadas
5
ACKNOWLEDGEMENTS
We would like to thank our host institution SOMASPA who provided us with materials and the needed support from the very beginning of our study. We would especially like to thank Maribel
Tejada, Julieta Carrión de Samudio and Rafael Samudio who have always been supportive throughout our research and who without which this investigation would have not been possible. We are also truly grateful and would like to thank the ANAM staff at Campo Chagres and in particular the rangers who would accompany us during our nightly observations. We are also grateful to Parque Municipal SUMMIT, who allowed us to take pictures of their primates for the creation of our pamphlet on Alto Chagres and Panamanian Monkeys. We are thankful to
Danylo Bobyk who allowed us to use his pictures for the Pamphlet. Additionally we would like to thank The Smithsonian Tropical Institute and McGill for providing the facilities, material and support for this investigation. Finally, we are grateful to our Envr 451 professors Rafael Samudio and Roberto Ibanez along with the courses teaching assistant Kecia Kerr for their continual enthusiasm and help.
6
HOST INSTITUTION INFORMATION
SOMASPA: Parque Lefevre, Vía Cincuentenario, Edificio INVESA, Local 3‐A [email protected]
The Sociedad Mastozoológica de Panamá (SOMASPA) is dedicated to the conservation of biodiversity. It is specifically concerned about the preservation of Panamanian mammals. They carry out scientific investigations, education programs, and cooperated with other institutions.
SOMASPA’s aim is to obtain the necessary knowledge on biodiversity in order to promote sustainable development and to increase conservation efforts in the country. They believe their work is essential in order to maintain the ecological integrity of Panama, particularly in the context of Panama’s national development strategy. They are already very active in the region of Alto Chagres and have realized several research projects in the area. Among other projects
SOMASPA is particularly involved in working on jaguar and the harpy eagle conservation
(SOMASPA 2007).
7
TABLE OF CONTENTS
EXECUTIVE SUMMARY ...... 1
RESUMEN EJECUTIVO ...... 3
ACKNOWLEDGEMENTS ...... 6
HOST INSTITUTION INFORMATION ...... 7
TABLE OF CONTENTS ...... 8
LIST OF FIGURES ...... 10
1. INTRODUCTION ...... 11
1.1 BACKGROUND INFORMATION ...... 11
1.1.1 Panama Conservation ...... 11
1.1.2 Geoffroy’s Tamarin ...... 12
1.1.3 Panamanian Night Monkey ...... 14
1.2 OBJECTIVES ...... 15
2. METHODOLOGY ...... 16
2.1 STUDY SITE ...... 16
2.2 DATA COLLECTION METHODS ...... 18
3. RESULTS ...... 20
3.1 GEOFFROY’S TAMARIN ...... 20
3.1.1 Distribution ...... 20
3.1.2 Abundance ...... 21
8
3.1.3 Ecology and behaviour ...... 21
3.2 PANAMANIAN NIGHT MONKEY ...... 24
4. DISCUSSION ...... 24
4.1 GEOFFROY ‘S TAMARIN ...... 24
4.2 PANAMANIAN NIGHT MONKEY ...... 27
4.3 COMPARING THE TWO SPECIES ECOLOGY ...... 29
4.4 LIMITATION AND IMPROVEMENT ...... 30
REFERENCES ...... 34
APPENDIX ...... 37
9
LIST OF FIGURES AND TABLES
FIGURES
Figure 1 – Geoffroy’s tamarin distribution map ………………………………………………………. … page 13
Figure 2 – Panamanian night monkey distribution map ……………………………………………… page 15
Figure 3 – Map of the conservation area of Alto Chagres ...... page 17
Figure 4 – Geoffroy’s tamarin habitat use ……………………………………………………………..…….. page 22
Figure 5 Geoffroy’s tamarin time partitioning …………………………………………………………….. page 22
TABLES
Table 1 – Data collected at Each Site where Primates were encountered ………..………….. page 19
Table 2 – Relative abundance and group size of Geoffroy’s Tamarin in Campo Chagres…page 21
10
1. INTRODUCTION
1.1 BACKGROUND INFORMATION
1.1.1 PANAMA CONSERVATION
Panama’s recent population growth is increasingly putting pressure on the country’s intact forests. The Canal Area faces the highest risk of degradation since it comprises most of the population and infrastructural development. Areas located closest to roads such as the
Transamerican Highway are also particularly at risk. However, a strong conscience towards natural conservation has emerged in the country, and the government has taken actions to protect their pristine forests by officially establishing many National Parks (Santa Maria 2003).
Nevertheless, establishing protected areas and initiating management plans does not guarantee the effective safeguard of ecosystems. It requires the joint effort and collaboration of governmental organisations such as ANAM, non government and international organisations and local communities. Furthermore, it is imperative to increase our understanding of the ecosystems and their interactions in order to achieve an effective conservation.
The destruction of Neotropical forests disturbs and puts the livelihood of many species in
Panama at great risk. Arboreal neotropical primates such as Saguinus geoffroyi and Aotus zonalis are particularly threatened by habitat conversion (Reid 1997). Primates play critical roles in maintaining ecosystem functioning by, for example, increasing seed dispersal and being important prey for other species such as the endangered jaguar. Primates also have a cultural
11
and economic importance in Panama. They have been known to be sold on the illegal pet trade and to also act as an important meat source for some indigenous communities and farmers. It is therefore essential to increase educational awareness about primate conservation and to continue monitoring their abundance and trends of their habitat loss (Pino 2007; Skinner 1985).
1.1.2 GEOFFROY’S TAMARIN
Geoffroy’s tamarin is fairly common and widespread within its range and has been classified as “least concern” by the IUCN (Marsh et al. 2008) and as under minor risk by the
Autoridad Nacional del Ambiente (Pino 2007). This primate is the smallest found in Panama, with a body ranging from around 20 – 29 cm in length and a tail of 31 ‐42 cm long (WNPRC
2009). This squirrel‐like primate is often located in secondary disturbed forests and occurs through out the moist and dry tropical forests of Panama, not necessarily restricted by altitude and humidity (Frey 2000). Within a habitat, the extended family groups of 4‐ 15 individuals generally stay clumped (Skinner 2005). However, the average group size, recorded for Saguinus geoffroyi by Dawson in 1977 was 5‐7 individuals. Saguinus geoffroyiis is a polygamous species with breeding season occurring between January and February. Normally, in a group, only one of the female tamarin will breed and later give birth between April and June to one or two offspring (Marsh et al. 2008). The home range of the group is normally from 9.4 to 24 hectares depending on resources availability and distribution (Dawson 1979). The males of a troop often have an aggressive behaviour toward other members (WNPRC 2009). They use vocal calls – birdlike long whistles – in order to warn others of nearby danger. Their diet consists primarily of
12
fruits and insects. During the dry season, however, they often resort to eating nectar (Frey
2000).
The primate’s range extends from Central and eastern Panama to Colombia. It remains the most northerly located member of its family. The exact western limit is not clearly defined, but according to Reid (1997) they are present west of the Canal area. A wide distribution has been recorded for Geoffroy’s tamarin in Eastern Panama, but its local distribution remains variable (Skinner 1985). Their presence on the Pacific coast has been linked to their preference for its drier forests. (Marsh et al. 2008).
Figure 1: Geoffroy’s tamarin Distribution Map 13 Source : Marsh et al. 2008
1.1.3 PANAMANIAN NIGHT MONKEY
Aotus zonalis IUCN conservation status is currently defined as data deficient (Cuaron et al. 2008), but ANAM classified them as vulnerable (Pino 2007). It displays a short brown and grey fur with a body length that ranges between 24‐37 cm and a tale being 31.6‐40 cm long
(Nowak 1999). The Panamanian night monkey has very large eyes suitable for its nocturnal lifestyle and they have been recorded to be most active at dawn and dusk (Cuaron et al. 2008).
They are socially monogamous living in small groups ranging from 1 to 9 individuals. The troops are usually formed of an adult pair and the parental care is primarily carried out by the male.
Aotus zonalis are predominantly located in primary and secondary forests. One troop normally uses a home range of 6 to 10 hectares (Svensson 2007). During the dry season their food sources become clumped, constricting to the size of their range. Their sleeping sites consist of thickets and branches of bamboo and shrubs, concavities and holes in trees, epiphyte masses, and vines supporting trees (Rathbun and Gache 1980). They make a variety of different vocal sounds which are not used to communicate directly with other members. Monotonous vocal calls are usually given in coordination between pairs (Svensson 2007).
The Panamanian night monkey occurs from the Panama lowlands to Northern Colombia
(Reid 1997). The major threats to this primate are still widely unknown. Deforestation however has been documented to be taking place in a majority of the Panamanian night monkey’s range.
Approximately thirty percent of the forests in its range in Panama and ten percent in Colombia have been converted to agriculture (Cuaron et al. 2008).
14
Figure 2: Panamanian night monkey Distribution Map Source : Cuarón et al. 2008
1.2 OBJECTIVES
The goal of this investigation was firstly to gather data from the field and literature reviews on two primate species which are currently understudied: the Panamanian night monkey and Geoffroy’s tamarin.. We attempted to describe Geoffroy’s tamarin troop structure and composition, estimate its distribution and abundance, assess its pattern of activity, diet and habitat use and characterize its interaction with other species. We also attempted to provide explanations for the absence of Panamanian night monkey field sightings. In addition, we aimed to compare the two species ecology and behaviour. However, because of our lack of data on the night monkey, this part of the objectives became limited. This study took place and focus on the
15
area of Campo Chagres (located in Chagres National Park). More information on these two primate species would help develop improved conservation practices.
Furthermore, we aimed to realize a brochure on the ecology and conservation of primates in Alto Chagres conservation area and Panama. Its main goal consists of acting as an educational tool to provide general information on the conservation area and the 8 primate species present in Panama to park visitors, the general public and tourists.
2. METHODOLOGY
2.1 STUDY SITE
The conservation area of Alto Chagres is located on the east side of the Canal, in the
Colon and Panama provinces. It includes the Chagres National Park and the south portion of
Portobelo National Park. The forests of Alto Chagres are considered to be the most effectively preserved in all of Panama (Pino 2007). The conservation area is a hotspot of biodiversity. The area supports many bird species, amphibians, reptiles, and mammals. Some animals of high conservation importance such as the Harpy eagle, the Jaguar and several primate species occupy the region. Notwithstanding, species in this area are still facing threats due to infrastructure development, hunting and land conversions for agriculture (Svensson 2007).
One of the main objectives of the Alto Chagres conservation area is the preservation of ecological processes that maintain the health of the Chagres River and its capacity to provide
16
environmental services to thousands of Panamanians. Indeed, the Chagres River supplies around 40% of the water required for the Panama Canal operations. It also provides a significant proportion of the water for domestic use and hydroelectricity of Colon and Panama City (ANAM
2006).
This investigation was carried out from January to April 2009 in Campo Chagres, located in the Alto Chagres conservation area. Campo Chagres is a site of the Chagres National Park adjacent to the Alajuela Lake, at 40 km from Panama City, as shown on figure 3.
Campo Chagres
Figure 3. Map of the conservation area of Alto Chagres, including Campo Chagres Source : Pino 2007
Campo Chagres is dominated by moderate hills formed by sedimentary rocks. The highest elevation does not reach higher than 200 meters above sea level. During the dry season precipitation levels on average do not reach higher then 60 mm and temperatures remain above 18 degrees Celsius (Santa Maria 2003). The site consists of a lowland semi‐deciduous 17
forest with areas of dry forest and young moist tropical forest (Svensson 2007). The mosaic of vegetation is mainly due to a sandy limestone layer covering some areas which increases soil drainage and favours vegetation more typical of dry forests. Despite its protection by ANAM, the area is marked by important human disturbances mainly due to its proximity to a populated area (Chilibre) and to previous land conversion to pastures (Santa Maria 2003).
2.2 DATA COLLECTION METHODS
In order to study the ecology and behaviour of Saguinus geoffroyi and Aotus zonalis, we combined field observations and literature review. For arboreal primates and Neotropical mammals, transects is the most commonly used method to collect field data and estimate population density and abundance (Chapman 1988; Pino 2007). Four transects of varying lengths were selected based on existing trails present in Campo Chagres (see Appendix 2). The total length of the transects was 7.2 km and they were walked at an average speed of 3,4 m/s.
Transects were walked along by two, or three observers. For Geoffroy`s tamarin, observations were realized in the morning (search time from 6:00 to 10:00) and in the afternoon
(from 14:00 o 18:00). Saguinus geoffroyi were usually localized by hearing their calling sound.
The Panamanian night monkey was searched during the night (from 6:00 to 9:00 PM). The monkeys were searched using headlamps and high powered flashlights.
When a group was encountered, data regarding the animals and habitat were recorded and gathered on a data sheet (see Appendix 1). To obtain more precise data on the troop composition and individuals’ behaviour, the observers left the transect line and follow the group if necessary. Table 1 illustrates the information which was gathered during each sighting. The 18
age categories (infant, juvenile, adult) were sufficiently broad for field use. However, older tamarin juveniles (from about 12 months of age) were extremely difficult to distinguish from adults (normally 18 and greater months of age) (Skinner 2005). The behaviour of the primates during initial sighting and after being disturbed by the observers was recorded (behaviours included: moving, feeding, resting, grooming and socializing). The observers also determined the canopy level where the groups of primates were located. The different levels were classified under 4 categories: ground level (below 1 meter), low (1‐5 meters), medium (5‐15 meters) and high (15+ meters). The identification of predominant tree species and dominant vegetation was also conducted on the field and later compared to previous studies. In addition, the presence of other species in the area and their interaction with the primates was recorded. Geoffroy’s tamarin identification of sex was not possible in the field because of the small size of the animals and lack of gender dimorphism (Skinner 2005).
Animal Habitat
Modes of initial detection (sight, vocalizations, sounds Type of forest (dry/wet) in the vegetation) Dominant vegetation Group size Other animals present Age categories (Infant , Juveniles, Adults) Behaviour (Moving, eating, grooming, resting, socializing) Habitat use (ground, low, medium, high canopy level)
Table 1 Data Collected at Each Site where Primates were encountered
19
The transects and troops locations were further transposed on a land use map (See
Appendix 2). In this investigation abundance of Geoffroy’s tamarin groups was calculated as the number of groups encountered divided by the total distance traveled by observers (groups/km), following the methodology used by Pino (2008). Based on previous investigations it was assumed that each different sighting consisted of a different Geoffroy Tamarin group (Pino,
2008; Skinner, 2005). It must be recognized that this assumption is arbitrary and most probably an overestimation.
3. RESULTS
3.1 GEOFFROY’S TAMARIN
Transects of a distance of 45,75 km in total were travelled in 46,5 hours and 9 different groups of Geoffroy’s tamarin were localized and observed. These observations allowed us to gather information on the distribution, abundance, behaviour and ecology of Geoffroy’s tamarin in the area of Campo Chagres. Our observations are summarized in appendix 3.
3.1.1 DISTRIBUTION
The map Tamarin’s troops observed and transects location (see appendix 2) indicates the estimated location of the troops sighted. The areas where the tamarins were observed are characterized by a predominantly semi‐deciduous vegetation. The troops were usually sighted in dry patches of the forest, sometimes slightly humid, but never in the most humid parts (for
20
example close to the lake). The tree species regularly present in the areas where Geoffroy’s tamarins were sighted are listed in the appendix (see appendix 4). This list includes evergreen as well as deciduous trees.
3.1.2 ABUNDANCE
Abundance was calculated by dividing the number of groups observed by the distance travelled on transects. As demonstrated in table 2, an abundance of 0,2 group per km was calculated.
Abundance Average Maximal number Minimal number Number of group size of individual per of individual per groups Group/km Ind/km group group observed
0,20 0,74 3,78 7 2 9
Table 2 Relative abundance and group size of Geoffroy’s Tamarin in Campo Chagres
3.1.3 ECOLOGY AND BEHAVIOUR
Troop structure and composition
The tamarins were always observed in groups ranging from 2 to 7 individuals. The troops were principally composed of adults: during 5 sightings the groups only consisted of adults and during 4 sightings the groups included adults with one juvenile. No infant were observed on the field.
21
Habitat use
As shown in figure 4, Geoffroy’s Tamarins were
mainly observed in the superior (63 % of the time
observed) and intermediate (33 %) strata of the
vegetation. They were rarely seen in the lower
strata (only 4% of the time) and never at the Figure 4 Geoffroy’s Tamarin Habitat Use ground level. They were initially sighted in different tree species (Ficus spp., Anacardium occidentalis, Bursera simaruba, Gustavia superba, etc.) and they do not seem to have a preference for a particular species, although they were sighted more often in Anacardium excelsumduring the last week of field observation. Also, the troops were travelling, jumping from tree to tree, without apparent selection of species. They would use all kinds of trees (deciduous and non deciduous) and vines, but very rarely palms.
Pattern of activity
The 9 groups of tamarins were
observed for a total of 287 minutes.
Figure 5 summarizes their pattern of
activity. Travelling was from far the
most important activity, which was
accomplished approximately 83% of Figure 5 Geoffroy’s Tamarin Time Partitioning the time they were observed.
22
Tamarins were also observed while grooming and resting (respectively 8 and 6 % of the time observed).
Vocal communication (birdlike squeals and whistles) between the members of the troop was important and it was estimated to occur around 80% of the time they were observed. The main purpose of the communication seemed to be the indication of their position to other members of the troop located farther away and to warn them of human presence. It was also common that one of the members of the troop (apparently the dominant male) would stay hind screaming aggressively at us/the observers while the rest of the troop escapes. The tamarins were almost never observed while eating. One individual was seen eating an insect and one other an Anacardium occidentalis seed (a cashew) during the last days of observation in April.
Interaction with other animal
The only direct interaction with other animals that could be observed was with a bird of prey1.
When the bird did pass above the area where two Geoffroy’s tamarins were, they quickly went from the upper canopy to a lower stratum, apparently to hide from the predator. The tamarins also seem highly affected by human presence: when they spot observers, they would often increase communication between troop’s members, produce aggressive squeals and rapidly escape in the forest. When walking along transects or following tamarin’s troop, other animals were observed such as Choloepus hoffmanni (Two‐toed sloth), Bradypus variegates (Three‐toed sloth), Nasua narica (White‐nosed Coati), Sylvilagus brasiliensis (Dice’s Cottontail) and a large
1 Observed on April 17th, 2009 23
number of birds (toucans and unidentified species). These animals did not seem to interact directly/actively with the tamarins and they probably cohabit passively.
3.2 PANAMANIAN NIGHT MONKEY
18,9 km were walked at night time along the different transects in Campo Chagres (see appendix 2) in 22,5 hours and no Panamanian night monkey was observed.
4. DISCUSSION
4.1 GEOFFROY ‘S TAMARIN
On abundance
Determining the number of groups of Geoffroy’s tamarin observed was very difficult since we do not have any system of individual identification. For technical purposes and based on previous investigations (Skinner 1985 and Pino 2007), we concluded that each observation comprised of a different group, totaling 9 groups. However, it represents an important limitation to our study. The identification of these groups is uncertain and arbitrary but there still remains the possibility that some of the monkey sightings were of the same group.
Therefore, it is likely that the tamarins’ abundance calculated for Campo Chagres was overestimated, as it is often the case in mammal population (Brugiere 2000).
In spite of this uncertainty, it is possible to compare the data obtained with those of other studies. The abundance found (0.2 group/km) is fairly close to another study’s result
24
(0,133 group/km) that was conducted north of Campo Chagres in Chagres national park (Skinner
1985). This study suggests a very irregular and inconsistent distribution within the monkey’s suitable habitat in Alto Charges. This may suggest that tamarins have local variations in abundances in the area of Alto Chagres. This patchy distribution may be related to differences in environmental conditions between areas and factors such as human disturbance. It would need to be taken into consideration when trying to predict primate abundance.
Another investigation studying primate abundance in La Llana, a site located in Alto
Chagres, found little presence of the Geoffroy’s tamarin (0,014 group/km) (Pino 2007). Yet this investigation was made in the Northern part of the Chagres National Park located in a more elevated region with higher precipitation. Primary forest represents most of this area’s vegetation, with few secondary forest located next to agricultural land. These results are consistent with other investigations that suggest Geoffroy’s tamarin preference for early succession forest and secondary forest over dense primary forest. For example, Skinner (1985) encountered tamarins the most often in younger forest (30‐80 years). The canopy cover tends to be lower in young forest resulting in a denser understory cover. Geoffroy’s tamarin is known to prefer areas of moderate or dense understory as it is seen in older secondary growth forests
(Frey, 2000; Kinzey, 1997; Reid, 1997). This information supports the relatively high abundance found in Campo Chagres, this area being mostly covered by young secondary forests, which is a habitat of predilection for Geoffroy’s tamarin.
25
On habitat and distribution
The tamarins’ troops observed in Campo Chagres were encountered mainly in areas of deciduous forest and in dry patches of semi‐deciduous forest. This was confirmed by the superposition of tamarins sighting locations on a land cover map (see appendix 2). Thereby, the list of tree species most commonly encountered at sighting sites (see appendix 4) encompasses a mixture of deciduous and evergreen trees. An important proportion of the species reported, such as Bursera simaruba, Pseudobombax septenatum, Pachira quinata and Cavanillesia platanifolia, are characteristic of dry forests and limestone soils. Also, some (but not all) tree species being part of Geoffroy’s tamarin alimentation are found in this list (e.g. Gustavia superba, Anacardium excelsum, Ficus spp. and Cecropia spp.) (Emmons 1997; Skinner 1985).
Finally, the presence of emergent trees such as Ceiba pentandra, Anacardium excelsum and
Cavanillesia platanifolia is essential for the provision of shelter and sleeping sites (Skinner 1985)
(Emmons, 1997). Campo Chagres , therefore, provides a suitable habitat for Geoffroy’s tamarin with the presence of of adequate vegetation for this primate livelihood.
On troop composition and structure
The biggest group observed was formed of 7 individuals but most of the troops ranged from 2 to 5 individuals with an average group size of 3.78. This result seems lower than the size proposed in the literature (up to 14 individuals) (Emmons 1997; Kinzey 1997) . It is likely that the groups of two individuals observed were only a part of larger groups that could not be localized due to the rapidity of the tamarins’ movements. The fact that we did not observed any infant is notable; an explication could be that the gestation period had not ended. The gestation period
26
normally occurs from 140 to 145 days, the majority of the births occurring from late April to early June (Frey 2000). It was noticed in the field that some primate individuals were significantly slower than others, which might suggest that these were pregnant female individuals.
On behavior
Our results illustrate that the Geoffroy’s tamarin was most often located on the medium and high levels of the canopy. It was at these levels that the troops were observed to rapidly travel away from the observers. Individuals were observed to leap between trees using the peripheral branches Garber (1979) stated that the rapid movements of foraging and capturing insects for food have been observed to occur mainly on small, thin and flexible branches. The study also suggests that the tamarin’s have a preference for these thin supports during travelling. Their agile movement is dependant on the presence of flexible vegetation (Garber,
1980).
4.2 PANAMANIAN NIGHT MONKEY
The Panamanian night monkey’s results indicates that they were absent of Campo
Chagres during the timeframe of our research (January to April 2009). A previous investigation, however, had concluded that Aotus zonalis were present in Campo Charges during the wet season and even recorded the highest abundance among 3 sites in Chagres National Park
(Svensson 2007). Many explanations can account for these discrepancies in the results. One
27
possibility is that the methodology used to investigate the night monkeys was inadequate. For example, these primates are known to be very sedentary especially during the dry season and it is possible that their location could not be sighted from the path. However, the research mentioned above (Svensson 2007) used the exact same methodology as the present study.
Furthermore, it seems improbable that the methodology represents the cause of the absence of observations because of the significance of the search effort (18,9 km in 22,5 hours) during the investigation. Thus, other reasons should be found in order to explain the lack of observations of night monkeys in the area.
This investigation was conducted during the dry season (January to April), a period when there is an absence of fruits and flowers in the flatlands, as it was also observed on the field in
Campo Chagres (see Appendix 7). Thus, we hypothesized that the night monkeys have migrated to other regions in Chagres National Park, such as Cerro Azul or La Llana. These areas are more mountainous and experience higher precipitation throughout the year: fruits are therefore present even during the dry season. To verify this hypothesis further research on the migrating pattern associated to seasonality is necessary. One could possibly carry out a study in areas where we suspect the night monkey to migrate during the dry season and also investigate the presence of the two primate species in Campo Chagres during the wet season (from May to
December). Nevertheless, it is relevant to observe that the Panamanian night monkey is absent from Campo Chagres during the dry season for conservation purposes. It highlights the importance of investigating more about primate migration patterns and the need to protect their various seasonal habitats.
28
4.3 COMPARING THE TWO SPECIES ECOLOGY
Despite the absence of food source in the area of Campo Chagres, Geoffroy’s tamarin was successfully observed which indicates that their must be a difference in the ecology and behaviour of the two species. Both species are known to have similar diets comprising primarily of fruits, and occasionally insects, nectar and leaves (Kinzey, 1997; Reid, 1997). It is suggested that tamarins have intermediate to large home ranges (20‐40 ha) and extremely large day ranges (exceeds 1200 m) in comparison to other primates with similar body sizes (e.g. Aotus and
Callicebus) (Kinzey, 1997). On the contrary, the Panamanian night monkey is considered as a sedentary species: it has been observed to spend several hours in a single fruit tree, sitting quietly and moving around only occasionally (Emmons, 1997). Another study found an average territory size of 9,2 ha and an average distance travelled at night of 708m (Wright, 1989). This difference in ecological behaviour can partly explain why we were able to observe Geoffroy’s tamarin and not the Panamanian night monkey. The large territory of the tamarin increases the chance of finding food in Campo Chagres, especially during the dry season. It should be noted, however, that during the investigation the tamarins were rarely observed eating. This suggests that they might also, during the day, travel to farther areas where food is available. This is further supported by the analysis of Geoffroy’s tamarin activity pattern (see section 3.1.3) which emphasizes the high proportion of their observed behaviour allocated to travelling. In April, it was noticed that one tree species (Anacardium excelsum, commonly called Espavé) in Campo
Chagres had fruits readily available. During this period, the tamarin groups were often observed
29
in this tree and were seen eating a seed2.The sedentary comportment of the night monkey decreases their food foraging opportunities and searching fruits and insects at night is more difficult than during the day (Cawthon 2005). These two factors might push the night monkeys to migrate seasonally to different areas where more food sources are available.
4.4 LIMITATIONS AND POTENTIAL IMPROVEMENTS
As in all scientific investigation, the methodology used in this study comes along with some limitations. Even if the possible was done to minimize the impact of these limitations, they still need to be discussed. FirstI it was practically impossible not to disturb the behaviour of the
Geoffroy’s Tamarin during our study. Rasmussen (1998) states that habituation of primates to an observer’s presence is a necessary and often arduous process to collection of data. It was shown that the tamarins’ tendency to run away decreased as they became more habituated
(Rasmussen 1998). Thus, we would have had to observe the same group for a long period of time for the Geoffroy’s tamarins to habituate themselves to our presence. During the experiment, the observers would alert the primates from a distance. In multiple cases individual tamarins would stare at the observers and alert other members using very distinct sounds. In the majority of cases they would also stop their current activities (eating, resting, etc.) in order to quickly move to other areas of the forest. This provides an explanation for why the primates were travelling during most of the observation.
2 Observed on April 16th, 2009 30
The fact that the observations only lasted during short periods of time represents another limitation to our study. The Geoffroy’s Tamarins are very agile and rapid, which creates a real challenge to try and successfully keep track of and observe groups from the understory of the tropical forest. Observers rarely could follow groups for more than forty minutes.
The fact that our transects were trails also limited the extend of our research. The trails were human‐disturbed areas that do not act as the perfect environment for the sighting of primates. The capacity to locate the monkeys by their sound from far away was a factor that helped us reduce this limitation. Also, the lack of leaves on the trees during the dry climate increased the visibility for localizing groups. Finally, our transect selection process was not random, which might have affected our calculation of abundance. In fact, when we knew where a group territory was located, we were tempted to go back to the same area, which would have lead to an overestimated abundance. However, s it must be recognized that the objective of our study was not only to estimate population abundance, but also to gather data on tamarins’ ecology and behavior. Therefore, going more in areas where troops are known to occur allowed us to observe a larger number of groups in more detail and increase sample size.
In addition, it is likely that the tamarins’ abundance calculated was an overestimated because determining the number of groups observed was very difficult. This limitation could be minimized by successfully continually observing the primate troops for longer periods of time and collecting more information about the troop’s composition. These observed details would help characterize the groups by their most visible and distinct features,
31
such as for example to presence of a specific number of small juveniles. Observers might then be able to successfully distinguish between the different groups observed.
Other techniques such as pooling local expert opinions for estimating mammal densities in tropical rainforests could also have been used for assessing the primate density (Van der
Hoeven 2004). This less costly and time consuming technique has been found to produce comparable results to the transect methods. It also has been found useful for long term monitoring of mammals and when transect methods do not provide enough data to calculate densities.
4.5 CONCLUSIONS AND RECOMMENDATIONS
In conclusion, this study highlights the importance to extend research before formulating conclusions on the presence or absence of a species in an area. The tropical forest being a changing and highly complex system, various scales (temporal and spatial) need to be considered in order to get an accurate understanding of the dynamics. For example, the case of the Panamanian night monkey shows that patterns of migration and seasonal changes should be taken into consideration in the study of primates populations. This is essential to evaluate primate (or animal) distribution and abundance and to develop appropriate conservation strategies. As it was found in this investigation, primates might use a variety of sites at different period of the year. Therefore, the protection of primates might require the conservation of various forested areas/lands. This study also emphasizes the importance of connectivity
32
between habitats and of corridors establishment between protected areas of in order to allow the movement of animals.
33
REFERENCES
Aquino, R.; Encarnación, F. 1986. Population structure of Aotusnancymai (Cebidae: Primate) in Peruvian Amazon lowland forests. AMERICAN JOURNAL OF PRIMATOLOGY 11(1):17.
AutoridadNacional del Ambiente. 2006. ParqueNacional Chagres.
Brugiere David, Fleury Marie‐Claire. 2000 .Estimating primate densities using home range and line transect methods: A comparative test with the Black Colobus. Primates 41(4): 373‐ 383.
Cawthon Lang KA. 2005 July 18. Primate Factsheets: Owl monkey (Aotus) Taxonomy, Morphology, & Ecology Taxonomy, Morphology, & Ecology.
Cuarón, A.D., Palacios, E., Morales, A., Shedden, A., Rodriguez‐Luna, E. & de Grammont, P.C. 2008. Aotus zonalis. In: IUCN 2008. 2008 IUCN Red List of Threatened Species.
Dawson, C. A. (In press): Composition and stability of social groups of the tamarin, Saguinusoedipusgeoffroyi, in Panama: ecological and behavioral implications. InThe biology and conservation of the Callitrichidae. Kleiman, D. G.WashingtonDC, Smithsonian Press.
Dawson, G.A. 1979. The Use of Time and Space by the Panamanian Tamarin, Saguinus geoffroyi. Folia Primatologica. Vol. 31, 253‐284.
Di Fiore, A., and E. Fernandez‐Duque. 2007. A comparison of paternal care in three socially‐ monogamous neotropical primates. American Journal of Physical Anthropology:99‐100.
Emmons, L. H. (1997). Neotropical Rainforest Mammals: A Field Guide, Second Edition. Chicago and London: The University of Chicago Press.
Frey, D. 2000. "Saguinusgeoffroyi" Animal Diversity Web.
34
Garber, P.A. 1980. Locomotor behavior and feeding ecology of the Panamanian tamarin (Saguinus Oedipus geoffroyi, Callitrichidae, Primates). International Journal of Primatology1: 185‐201
Kinzey, W. G. (1997). New World Primates: Ecology, Evolution and Behavior. New York: Aldine de Gruyter.
Marsh, L., Cuarón, A.D. &de Grammont, P.C. 2008. Saguinusgeoffroyi. In: IUCN 2008. 2008 IUCN Red List of Threatened Species.
Marshall, A. R., J. C. Lovett, and P. C. L. White. 2008. Selection of line‐transect methods for estimating the density of group‐living animals: Lessons from the primates. American Journal of Primatology70:452‐462.
Nowak, 1999. Walker's Primates of the World. the Johns Hopkins University Press, Maryland, 193p.
Rasmussen, Dennis R. "Changes in Range Use of Geoffroy’s Tamarins (Saguinus geoffroyi) Associated with Habituation to Observers." Folia Primatol 69 (1998): 153‐59. ATES 21:211‐219
Rathbun, G.; Gache, M. 1980. Ecological survey of the night monkeys, Aotustrivirgatus, in Formosa Province, Argentina. PRIM
Reid, F. 1997. A Field Guide to the Mammals of Central America & Southeast Mexico Oxford University Press, New York.
Rolando Aquino, F. E. 1988. Population densities and geographic distribution of night monkeys (Aotusnancymai and Aotusvociferans) (cebidae: Primates) in Northeastern Peru. American Journal of Primatology14:375‐381.
Santamaria, Dilia, Polanco, José, Martinez, Ana and Tajada, Isis. Evaluacion Del Estado de Conservacion y Amenazas al BosqueCaducifolio y BosqueSemicaducifolio Del Parque Nacional Chagres. 2006. AssociacionNacional Para la Conservacion de la Naturaleza (ANCON).
Skinner, C. 1985. A field study of Geoffroy'stamarin (Saguinusgeoffroyi) in Panama. American Journal of Primatology9:15‐25.
SOMASPA, 2007
35
Svensson, M. 2007 Assessing the distribution and abundance of owl monkeys (Aotuszonalis) in Chagres National Park, Panama. Unpublished. M.Sc. Thesis Oxford Brooks University.
Wisconsin National Primate Research Center, 2009. Primate Factsheets.
Wright, P. C. (1989). The nocturnal primate niche in the New World. Journal of Human Evolution, 18(7), 635‐658.
36
APPENDICES
37