Sunday, October 20, 2013

Cordyceps: killer fungi

Most of the time, we see what's beautiful, enticing and admirable in the natural world.  However, we are all well aware that there are many challenges to the struggle for live of any living organism—predators, climate change, natural disasters, human activity—as we tend to see more and more of in the media, documentaries, and witness in person in our daily lives.  

Cordyceps wasp
Wasp killed by Cordyceps fungus in Panama
A few weeks ago during a visit to the Canopy Lodge in El Valle, I was walking around the gardens and spotted this unusual creature on a low palm frond.  Upon closer examination, I saw that it was a wasp - but something wasn't right.  This wasp had two large, white projections emerging out of its thorax, and white spines over its legs and other parts of its body.  It was motionless.  I knew exactly what had happened.

In tropical regions, there are some rather unlikely predators, and they kill in rather gruesome ways.  Aside from large cats, raptors, and many other predators out there, there exists the strange and ruthless world of Cordyceps—an endoparasitoid fungi that attacks insect and arthropod hosts.  When this fungus attacks a host, it releases mycelium, which replaces the host tissues.  It also causes a change in behaviour of the host, perhaps an ant or wasp, causing it (if a social insect) to leave its colony and climb up a branch or shrub and attach there before they die.  This change in behaviour ensures that the spores of the fungus will be released in the optimal surroundings to maximize distribution.   Once the host is in position, the mycelium then forms a fruiting body—usually a cylindrical, branched or complex projectionwhich emerges through the exoskeleton of the host.  Spores are released through this fruiting body.  Cordyceps means "club head", referring to the shape of the fruiting bodies.  The spores are very potent, and this killer fungus can wipe out entire colonies of insects.  Check out this video from Planet Earth.  
Cordyceps moth
Moth showing small Cordyceps fruiting bodies in Ecuador, 2010
Cordyceps cricket
Cricket killed by Cordyceps fungus in Ecuador, 2010
Cordyceps Bullet Ant
Bullet Ant - note the elongated fruiting body extending from back of head.  Ecuador, 2010
It sounds (and looks!) like something out of a grotesque sci-fi movie, but this is real.  In the time I have spent living and working in tropical humid environments, I have come across this several times.  I have seen moths, crickets, bullet ants, and other insects parasitized by these unusual killers.  Here are a few photos I have taken in recent years of various Cordyceps attacks. The fruiting bodies take on different forms and colours, depending on the species of Cordyceps (there are approximately 400 described species and many more remain undescribed), and I have never seen two alike. 

So its not just some mammals, birds, reptiles and other animals, even plants that have mastered their roles as predators, but an entire world of predatory and parasitic fungi, which continues to show us the complexity and diversity of the world we live in.  Incredible!

~ Jenn 

Monday, October 14, 2013

Great Curassows on Pipeline Road

It had been a little while since I had been to Pipeline Road and the Panama Rainforest Discovery Center, but when a friend called me up to go for a walk I was more than happy to head out to one of my favourite places on this planet.  We left early on the morning of October 11, and arrived at the entrance of Pipeline Road around 6:30 am, and the bird activity had just started.  We watched the hummingbirds at the Visitors Center, walked a short trail and spent some time on the tower before the rains started before mid-morning.  Highlights included a Great Black-Hawk and over 100 migrating Common Nighthawks seen from the tower.  Here is an e-bird checklist of the morning.  

Great Curassows
We didn't have a lot of time in the morning, but managed to get out before the heavy rains started and continued through the rest of the day.  As we were driving out on Pipeline Road, we spotted three large birds walking down the road ahead.  I quickly picked up my binoculars and saw that they were Great Curassows, the largest member of the Cracidae family in Central America.  Great Curassows are rare on Pipeline Road, due to years of over-hunting in the area.  In 2009, I had two sightings of Great Curassows on Pipeline Road, but far in, well past 15 km from the entrance.  Recently, there have been occasional sightings closer to the entrance, and this trio was less than a kilometre from the gate.  They were all in female plumage, but it was not determined whether one or more were young males.  We watched the trio for 10-15 minutes, until they moved off the road into the forest when a car came along, and were seen feeding on fruits under a Ficus tree not far from the road.  

Great Curassow
The Great Curassow (Crax rubra) is a large, turkey-like bird of the lowland humid forests of Central America and northwestern South America.  Males are stark black with a yellow knob at the base of its beak and white undertail coverts.  Females generally have a reddish-brown body and dark grey neck and head, sometimes with barring in the wings, and have a heavily barred tail.  Both sexes have a curled crest.  Their diet consists mostly of fruit, but they will also feed on small invertebrates and sometimes vertebrates as well.  They are often found feeding on the ground, and also spend time feeding and roosting in the mid-story and even the upper levels of the forest.  Due to over-hunting and habitat loss in many parts of its range, the Great Curassow is considered vulnerable by IUCN, and their populations are decreasing.  Hopefully with the extent of protected areas in Panama and throughout the Neotropics, their populations will stabilize and we will begin to enjoy regular sightings of these beautiful birds.  

We were going to carry on for a walk at Metropolitan Park in Panama City, but the heavy rain forced us to reschedule, that will be saved for drier day.  

~ Jenn 

Wednesday, October 2, 2013

Little-known Manatees of Panama

Finding Neotropical mammals is always a rewarding challenge.  There is a great diversity of mammals in Panama, over 230 species are found in this small country, in a wide variety of habitats.  It is the best place I know to see sloths, two species, in all of the Americas.  In certain places, common forest mammals such as Central American Agoutis and White-nosed Coatis are common.  Lesser Capybaras live along the banks of the mighty Chagres River, which feeds into the Panama Canal.  Panama is a wonderful place to search for mammals, but it is not as easy as it may seem.  Many Neotropical mammals by nature are nocturnal, which means spending time in the deep darkness of the forests to find them.  Certain species, like cats, are incredibly elusive.  Finding these animals requires patience and at times, may seem like a near-impossible task.  

I had heard rumors of a population of West Indian Manatees, one of Panama's rarest mammals, living in Lake Gatun.  Odd reports show up here and there, many of them are unfortunately of carcasses that float to the surface.  Manatees are fully aquatic, and live in tranquil, dark waters of shallow lakes, thus are rarely encountered.  Aerial surveys may be the best way to see these large mammals in quiet bays from above, other than that, a sighting of a manatee in Panama is a very rare occasion. 

On September 12, I guided a jungle boat tour along the Panama Canal and Lake Gatun.  We had perfect weather, and as we cruised around the waters and scanned the banks, we came across an abundance of animals - Snail Kites, American Crocodiles, Iguanas, White-headed Capuchins, Mantled Howlers, Limpkins, Proboscis Bats, and so much more.  About halfway through the tour (around 4:00 pm), as we glided in our little motor boat through the calm waters along the edges of Lake Gatun, I started to think about manatees, remembering that there are occasional sightings.  Not even two minutes later, we saw the large, rounded back emerge above the water surface, followed by the unique, round tail of a manatee.  We couldn't believe our eyes... a manatee!  Only metres from our boat!  We all saw it in great view.  Its true, they do exist in the dark waters of Lake Gatun.  Among many great wildlife sighting moments I have had, this is one of the most memorable.
Lake Gatun
The calm waters of Lake Gatun
So, what are manatees doing in the Panama Canal?  Information about the populations of manatees in Panama is not well-known, and there have been very little studies done to learn about their existence here.  In 1964, nine West Indian Manatees from Bocas del Toro and one Amazonian Manatee from Peru were introduced into Lake Gatun by the former Panama Canal Commission as a part of an aquatic vegetation control program.  The program was abandoned a few years later, and the manatees were left to live in the lake.  It is difficult to say how many manatees are here, but its not many; a study in 1980 estimated approximately 25 individuals, and a more recent study in 2008 resulted in 16 individuals seen in an aerial survey, this being the highest number ever recorded in Lake Gatun.  However, calves were seen so this population, although small, seems to be sustaining itself.  Hopefully the manatees of Panama will continue to live and reproduce in the waters of Lake Gatun. 

~ Jenn