Sea Turtles, Volunteers and Visitors

Sea Turtle Conservation Program: October Update

We’ve completed another month of the sea turtle conservation program on the Osa Peninsula, Costa Rica and we’re getting close to the end of the nesting season. After 4 months of tireless work by our field coordinators, field assistants and volunteers, we have registered a total of 1233 sea turtle nests, between Piro and Carate (Fig. 1). As I mentioned earlier, for logistical reasons, we cannot gather daily information from all beaches and visits to Rio Oro beach have been very limited, so this number of sea turtle nests should be considered a minimum; i.e., the actual number of sea turtle nests on these beaches is higher than reported here.

Figure 1. Total nests registered, according to month, beach and species. CM: Chelonia mydas agassizii, DC: Demochelys coriacea, EL: Eretmochelys imbricata, LO: Lepidochelys olivacea

Of these 1233 recorded nests, we know that at least 242 (20%) were predated. Of predated nests, 43% were by humans, while the remaining 57% were predated by dogs, pigs, crabs and other animals. We can reasonably estimate that approximately 10,600 eggs have been illegally removed between Piro and Carate for human consumption (assuming that each nest had 100 eggs and they were all taken).

If we focus on the Olive Ridley sea turtles (Lepidochelys olivacea), the most common sea turtle species on the Osa Peninsula, not taking into account the Rio Oro data, as the data that we have doesn’t appear to be representative of the real situation, we can see that during the 2010 season, Carate beach is where we find the greatest amount of illegal harvesting of eggs (Fig 2). Throughout the season, more than 50% of reported predation is caused by humans, a situation that hasn’t occurred on Piro and Pejeperro beaches.

Figure 2. Percentage of Olive Ridley sea turtle nests predated by humans and other animals according to month and beach.

Remember that you can help us save sea turtles that visit the southern part of the Osa Peninsula in several ways: 1) tell others about our project and the importance of protecting sea turtles, 2) by volunteering with sea turtles or 3) by making a donation to support our sea turtle program or the other conservation work that Friends of the Osa does on the Osa Peninsula.

Environmental Education, Miscellaneous

Osa Peninsula Butterfly Workshop

This August 16-19, La Leona Lodge organized a workshop about frugivorous (that means fruit-eating) butterflies with entomologist and curator of Lepidoptera, José Montero of INBio (National Biodiversity Institute of Costa Rica). This workshop was attended by several people in the area, including naturalist guides and employees of La Leona Lodge. José taught us about the methodology that he has been using in different parts of the country with great success for several years and now La Leona Lodge has begun to use, in order to generate information about butterflies of the Osa Peninsula.

Frugivorous butterfly trap on the Osa Peninsula

Frugivorous Butterfly Trap

The methodology used by José consists of traps that are placed in the canopy and the understory that attract butterflies with fermented fruit. Fruit is placed in these traps during the first week of each month. All butterflies captured during this period are identified, which gives a pretty good idea of the species richness in both strata of the forest, if sampling is performed at adequate intervals.

Jose shared with us some of his vast knowledge of frugivorous butterflies of Costa Rica, which, he tells us, make up between 40-50% of all Costa Rican butterfly species. He also told us how the species richness of frugivorous butterflies has greater variation vertically than horizontally; i.e. there is a greater difference between the canopy and the understory of the same site, than there is between different sites at similar heights.

Not content to talk only about butterflies, José also gave excellent lectures on the concepts of diversity, evenness, dominance and beta and gamma biodiversity, all fundamental concepts in the work he has been doing.

I would like to thank La Leona Lodge, especially Ifigenia Garita, for the opportunity to have participated in this activity. I also want to thank José Montero his great willingness to teach and share his knowledge.