Tapirs Currently Being Monitored

Silbo (5 year-old male) and Dedo (4 year-old male) have apparently dispersed permanently from the study area. They were last detected in September 2002. Both are offspring of Big Mama and have been making what I call "exploratory excursions" away from the study area for the past year. During these excursions (which all juveniles tapirs in this study have done), the animals will disappear for weeks at a time, and then return to their old home range for several weeks. Below, I outline a brief summary of typical juvenile independence/dispersal behavior observed during this study.

1. Offspring spend the first 12 to 18 months traveling with their mother. Apparently, this time frame varies depending on the reproductive activity of the mother - if she is ready to produce another baby the offspring is forced into independence earlier. If a new offspring is not expected, the young may stay with the mother for an extra few months.
   
   
2. Between 1 and 2 ½ years of age, the offspring remains within his natal home range but travels independently. He/she may occasionally forage and share daytime resting sites with older siblings that are still in the area.
   
   
3. At 2 ½ years, juvenile tapirs move just outside their natal home range, occupying the "no man's land" between the home ranges of adult tapirs in the area.
   
   
4. Between 3 ½ and 4 years of age, the juveniles make the exploratory excursions described above. Unfortunately, the project does not have sufficient funds to conduct systematic aerial tracking to determine just how far the juveniles are traveling during this time. They are normally away from the study area for 3 – 4 weeks at a time. They then return for 4 – 6 weeks, again taking up residence between established adult territories. Frequently, the juveniles will show up with extensive scaring from
   fights with other tapirs (photo right).
   
   
5. Finally, between 4 and 5 years of age the juveniles permanently leave their natal home ranges and do not return.

REPRODUCTION

Early in October the unmistakable tracks of a newborn tapir were observed in the area around Sirena. Since Big Mama is the only adult female occupying this region we all assumed it was hers. But not until Juan de Dios used the telemetry equipment to visually locate her during the day were we able to verify that she had given birth to another perfect male offspring.

He was named Nepal, after Patricia Medici's Labrador retriever, who is almost as cute. Big Mama got her name because of her size and because she had an offspring by her side when we first radio-collared her in 1995. She has continued to live up to her name ever since. Nepal is her 6th offspring in the 8 years we have been monitoring her, by far the most productive female in our study. Interestingly enough, of her 6 offspring, 5 have been male. The only female thus far is Prima, born last year.

The second offspring was discovered during a routine monthly observation of Playa in November. Since Playa lives in a more isolated site than Big Mama and is more reclusive we had no prior indication that she had given birth. It is for this reason we attempt to make monthly observations of all adult females to document births. I made the first sighting of Cabo ("Cove" in English) on November 5th and it appeared to be the same age as Nepal (based on size and coloration). Unfortunately, given the terrain, vegetation and nervousness of Playa, I have not been able to determine the sex of the baby. As he/she gets older Playa will become less wary and I should be able to get a good look at it in January.

Keep Those Babies Coming!!

Tapir Copulation:
On October 24th, Juan de Dios Valdez witnessed a mating bout between Big Mama and Thor. Juan was taking some photos of Big Mama's newest offspring, Nepal, when the adult male, Thor, showed up. Thor and Big Mama share the territory surrounding the Sirena Station. The following is Juan's account of the encounter.

Both Big Mama and Nepal were sleeping in a mud-hole about 800 m from the station when Thor approached. As Thor came closer he began those "hiccup" vocalizations tapirs make and, to which Big Mama replied with low-volume whistles. When Thor arrived at the mud-hole, both Mama and Nepal stood up and Mama started pushing Nepal out of the area. During the next 3 to 5 minutes, Thor mounted Big Mama 7 times without success. After the second attempted mounting, a considerable amount of viscous liquid was being secreted from Mama's vulva.

After the initial mountings Mama walked off approximately 50 meters, with both Thor and Nepal following. At one point Nepal tried to pass Thor to get closer to Mama but Thor prevented him by pushing him quite forcefully with his trunk. Finally, Thor managed penetration at 1:31 p.m. The copulation lasted 4.5 minutes. Both Mama and Thor remained quiet for approximately 30 seconds after separating. Big Mama then went in search of Nepal. While walking away from Thor, she excreted copious amounts of a milky substance from her vulva. As Mama and Nepal walked away, Thor ate a few leaves from the nearby vegetation and then began to smell and lick at the milky substance secreted by Mama.

So, with any luck, Big Mama should be giving birth to her 7th offspring sometime in late November 2003. We'll keep you posted.

MORTALITY

ONGOING PROJECTS

We continue to use radio telemetry to collect data on movement patterns of individual animals. The information is used to evaluate parameters such as activity patterns, home range size and location, habitat use, population density, and the distribution pattern of the population.

"Influence of Large Herbivores on Understory Vegetation Structure and Diversity."
This project is investigating the role large herbivores play in maintaining and shaping the plant communities of Neotropical forests. Specifically, we are examining how the removal of the large herbivores will affect the physical structure and floristic diversity of the understory vegetation in the lowland rainforest of Corcovado National Park. Many ecologists have documented the important roles played by large animals in seed dispersal, seed predation, herbivory, pollination, and predation, but until recently few have considered what would happen if the large animals were removed from the system. In order to simulate the removal of these herbivores from the forests, we will construct exclosures that will prevent them from foraging in selected areas.
Juan de Dios Valdez Leal has been collecting data on changes within 14 exclosures and control plots since September as part of his Master's thesis project. Most likely, Juan's data will reflect only changes in the physical structure of the forest understory. The first signs of alterations in diversity of plant species will not become apparent for some time. The plan is to monitor the exclosures for at least 5 years. We are also communicating with other tapir researchers about the possibility of implementing similar projects in South America.

This study is designed to investigate the possibility of using track counts to accurately estimate tapir population size. Unfortunately, due to the difficulties in working in tropical forest habitats and the secretive, nocturnal behavior of the tapir, a reliable method for estimating the size of a tapir population does not currently exist. As a result most management plans rely on track counts to estimate only the relative abundance of tapirs in the area. Although useful, this method cannot provide an accurate measure of population size unless it is calibrated with data from an area of known tapir density. Similar problems and limitations apply to population density estimates obtained with direct observations made along transects. Radiotelemetry studies can provide very accurate population density measurements but are time consuming and expensive. This study will combine the accuracy of radiotelemetry density estimates with the simplicity of transect methods to enhance the ability of wildlife managers to monitor tapir populations. This study is also a part of Juan's Master's thesis project. He has been conducting tracks counts and sightings along 10 kilometers of transects in the study area (5 km in primary forest and 5 km in secondary forest), very similar to what would be done in any conventional study. The difference in our case is that we know the true density of tapirs in our area. Therefore he will be able to formulate a correlation factor that can be applied to the transect data to estimate population density. In addition, once a month we will radiotrack the movements each tapir during a continuous 24-hour period to describe the average daily movement patterns of the tapirs inhabiting the study area. Later, we will use a computer program to overlay simulated transects on the telemetry data. This will help supplement our field data and refine the correlation factor.

NEW T-SHIRT FOR FUND RAISING

We all know that tapirs are the most spectacular animals in the Neotropics, but not all visitors to Sirena have such exquisite taste. In order to generate a few more dollars I designed a t-shirt illustrating the tracks of the more common mammals in the area. Each animal has the silhouette of the front and back foot, and below is given the scientific name and the common name in both English and Spanish. The shirts are on sale for $10 and as always the proceeds help to cover some of the room and board costs for those involved in the project.

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PUBLICATIONS

"Home Range, Habitat Use and Activity of Baird's Tapirs in Costa Rica"
by Charles Foerster and Christopher Vaughan was published in the September issue of Biotropica, which came out in October. Volume 34, Number 3, pp 423-437.