A Crabby Christmas

In the Indian Ocean, just west of Australia, there is a tiny island that is literally called Christmas Island. Admittedly, Christmas Island was simply named after the date it was discovered in 1643, and it is anything but a winter wonderland--indeed, it is covered in tropical rainforest (though, to be fair, there is plenty of mistletoe. . .). It serves as an important habitat for various species of birds, reptiles, and a few mammals. And crabs.
Every year, Christmas Island red crabs swarm to the shore of the island in their millions to release their eggs into the water. Interestingly, these swarms which are now threatened by human development on the island, may also be a result of human activity. In 1903, the MacLear's rat, one of the few mammals native to the island and a major predator of the crab, was killed off by introduced cats. With the rat gone, the crabs' population exploded. Yet today, a new invasive species is threatening the crabs--and much of the rest of the island as well.
This newcomer is the yellow crazy ant, an insect from Africa. These omnivorous ants will feed on anything they can overpower, and often kill and eat the small animals on Christmas Island. Crazy ants form what are known as "supercolonies": colonies with multiple queens that can coordinate with one another and effectively control a large area of forest. Because of this, they are notoriously hard to exterminate.
 However, progress has been made. In 2002, a poison-baiting program killed 99% of the crazy ant population in a test area, while leaving all of the red crabs alive.

Christmas Island red crabs like this one travel to the sea in gigantic swarms to lay their eggs. However, these migrations may be a thing of the past unless invasive ants are kept from devastating the island.

Mistletoe--The Praises of a Parasite

In some cases, it's easy to see how an animal or plant became associated with the holidays. Reindeer pull Santa's sleigh, conifer trees get made into wreaths and used as Christmas trees, and so on and so forth. But mistletoe? It's a rather unassuming plant, one that grows on other plants and gets nutrients from them--a parasite, in other words. And parasites, as we've seen before, usually don't have the best press. But mistletoes is more than just a parasite, and more than just a Christmas decoration. It is, in fact, a keystone plant in many forest ecosystems.

Although mistletoe fruit is inedible to humans, it is eaten by a vast array of other animals, and actually forms a large part of the winter diet of many fruit-eating birds, such as waxwings. Incidentally, mistletoe also indirectly contributes to the spread of other fruit-bearing plants: juniper trees reproduce more successfully if they have mistletoes, because this attracts fruit-eaters that may eat their berries. In Australia, out of the 240 species of birds that nest in the branches of trees, 75% have been recorded nesting in mistletoe.
In southeast Asia and Australia, mistletoe fruit are eaten by small birds called flowerpeckers. These birds, which have specially evolved digestive systems for dealing with mistletoe fruit, are the primary means by which mistletoe plants have spread through the Asian and Australian rain forests. 

The lesson to be learned from this is that there is no single description of an organism's ecological relationships. A mistletoes plant may be a parasite, but at the same time it is also a part of many other interactions in its environment, all of which would fall apart if it were removed. This is why, as environmentalists, we should take into account all living things, even parasites, in our ecological plans.

A cluster of mistletoe grows on a tree, green against the white and brown of winter. Although it is a parasite, mistletoe has a surprisingly important role in many ecosystems.

The Vanishing Vaquita

At only about four feet long, the Vaquita is the world's smallest whale. It is found only in the Gulf of California, which is why its name is in Spanish (it means "calf"). And there are only 97 of them left in the world. Of the remaining Vaquitas, around 35 die each year, mostly from becoming entangled in gill nets set to catch fish. If this rate continues, the whole specie could be extinct by 2018.

Yet little is being done. Gill net fishing is closely monitored, but it is still done in many parts of the world, including much of the area where the Vaquita lives. It is worth mentioning that these gill nets are often set up to catch totoaba, a fish that is itself endangered. It was not until 2008 that the US, Canada, and Mexico formally launched the North American Conservation Action Plan for the Vaquita, and by then it may have been too late. The Action Plan provided fishermen with compensation for switching to  "Vaquita-safe" gear; unfortunately only about a third of fishermen offered have taken up the option.

Curiously, despite the demonstrated popularity of whales and dolphins in public aquaria, the Vaquita has never been kept in captivity. Keeping and perhaps even breeding Vaquitas would be an excellent opportunity for marine parks like SeaWorld--which often come under fire from environmentalists for their supposedly unethical practices--to show that they can indeed make a contribution to conserving the animals they display. 

The Arctic National Wildlife Refuge: You Know the Drill.

Well, I sort of slipped up on my promise to continue posting again. But THIS TIME I mean it!
In other news, today's article is about something that's thematically appropriate for this time of year--the Arctic National Wildlife Refuge, and the debate over whether it should be opened for oil drilling. Here's some background: The refuge sits atop one of the largest single deposits of untapped oil in the United States, and with supplies of oil dwindling it has been proposed by many that these deposits should be used to their fullest extent. After all, the argument goes, doing so would have the further benefit of reducing American dependence of foreign oil.
The downside, of course, is that the infrastructure for the drilling, as well as the waste it creates, is an environmental hazard. As the Deepwater Horizon oil spill of four years ago proves, an oil well can create devastating runoff if it is destroyed or damaged somehow.
The area that has been proposed to be opened for drilling encompasses much of the range of the Porcupine herd of caribou, or reindeer. Numbering over 169,000 animals, this is one of the largest herds of caribou in the world, and development of the area would block their access to their traditional breeding grounds.

 I personally believe that the Arctic National Wildlife Refuge should remain just that--a refuge. Making allowances for any sort of development in protected areas will simply open the door for them to be exploited in other ways in the future. And then what would happen to them?

A herd of caribou grazes near an oil derrick. Right now, oil drilling and wildlife lead an uneasy coexistence--but that may not be the case for much longer.