October 2009


Back in the 1970’s the BCI dining facility offered food to both the human and animal residents of the island.  Spider monkeys were regular customers, and their increasing aggression towards humans over the years contributed to the prohibition on feeding any animals.  However, for a time, flocks of agoutis, coatis, monkeys, and even tapirs would come to the BCI dinner bell.  Poaching was still a problem on the south end of the island, and part of the rationale was that these hand outs would help restrict the tapir movements and reduce their likelihood of being shot.

This wildlife spectacle was popular among biologists (except for the aggressive monkey part) and they turned their scientific eyes to the interactions between species lolling around between meals.  To their surprise, they watched troops of coatis grooming ticks off the tapirs.  The tapirs would even lay on their sides to give the scrambling insectivores access to their hard-to-reach areas.  Karen Overall grabbed her binoculars and field book and counted over 100 ticks eaten by coatis in their 10-20min grooming bouts. She figured this offered the 5kg coatis a 20-400ml blood meal, which was a decent supplement to their normal fare of spiders, insects, and fruit.

The Good Olde Days

The Good Olde Days

These few tame tapirs were lab favorites, and given names like Alice and Louie.  Deedra McClearn noted in 1990 that, after the termination of free food handouts, and the death of Alice and Louie (after 25+ years of entertaining biologists), no further coati-tapir interactions had been seen.  Alice and Louie’s children kept to the forest, and coatis seemed to be content with their fruit and spider diet. Deedra suggested that this mutualism between coatis and tapirs was probably a temporary phenomenon resulting from the artificial feeding at the dining hall.

Nineteen years later our cameratrap captured this video of a tapir on BCI.  Probably some great, great, great, grand child of Alice and Louie – this poor guy is loaded with ticks.  The parasites don’t seem to bother him, as he feeds casually in front of our camera, his mind obviously on other topics (and I don’t mean food).

BCI is a more natural setting now, with no hunting anywhere on the island and no free handouts to the animals. Recovery of ocelot, puma and jaguar populations on BCI are just rewards for ecologists.  However, I can’t help thinking that Louie the IV here wouldn’t prefer the good old days of papaya handouts and trips to the coati spa.

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Animal density can be accurately estimated from camera trap photos. That is what our intern Lennart Suselbeek argues in his MSc thesis. Lennart took all 862 paca visits that our camera traps recorded in ten different 1-ha plots on BCI ; over 6000 camera traps nights in total. Lennart went through all photos to try individually recognize these animals by the unique spot patterns on their sides (see picture). He found 54 different individuals.

Then, Lennart estimated paca densities for each plot in two ways. First, he used a generally accepted Capture-Recapture model (SECR) that uses the individual identities. Then, he used a new “Random Encounter Model” (REM) that uses visitation rates, movement speeds and activity levels but not individual identities. The two estimates nicely correlated across the ten sites, which suggests that the REM, developed by our collaborators Marcus Rowcliffe and Chris Carbone, does a good job. This means that we can use camera traps to estimate densities of mammals that we cannot recognize.

And so did Lennart. He just received his MSc degree from Wageningen University and immediately started a PhD on seed dispersal by rodents with Patrick Jansen. Congratulations Lennart!

Paca in the lab clearing

Paca in the lab clearing

This mama opossum showed up on our camtrap, carrying five young on her back. With the infrared flash reflecting in 12 eyes, she almost looks like a Christmas tree.

The second photo shows an opossum with the tail wrapped around a bunch of leaves. These will likely furnish this animal’s nest.

Photos such as these illustrate how we can get information on the timing of breeding and the size of litter from camera traps.

Opossum with five young caught by a camera trap

Opossum with five young caught by a camera trap

Opossum carrying leaves with her tail

Opossum carrying leaves with her tail

Jackie Willis and Jenny Murtaugh were recently combing through our 2008 ocelot data to identify the spot pattern of each individual.  One picture didn’t match any…becuase it was a jaguar!  We didn’t notice it at first because it was very close up.

Here’s the image

2008 Jaguar

2008 Jaguar

The camera was set a bit high, but did capture an ocelot as well, which you can see is a much smaller animal than this jaguar picture.

This jaguar was photographed only once, on 3 Oct 2008.  The following year both Jackie and our cameras got pictures of a jaguar as well.  However, the spot patterns don’t match up.  Thus, it seems that there was one jaguar on BCI for a short bit in Oct 2008, and then a 2nd jaguar in 2009.  Jaguars don’t mind swimming, so its not surprising that they would come to BCI for lunch every once in a while.

Here is an agouti passing in front of our camera traps with a large seed in its mouth: an Astrocaryum palm nut. The photo was taken in September, months after the fruiting period of the palm. The agouti took this nut out of a cache and it is carrying it to a new spot to recache it. Most likely, this agouti stole the seed from another agouti. And most likely, this agouti will in turn loose its seed to another seed-robbing agouti. Seeds thus move multiple times, without getting eating, and get dispersed further and further from where they started their journey.

Camtrap agouti with seed