Friday, April 27, 2012

Feral Cats & Kakapo Birds

In today's lecture about feral cats and wild birds, we discussed briefly the differences in predation levels with cats on islands, and I believe someone also asked about the issue of flightless birds. As Professor Tantillo demonstrated, a lot of the research that paints cats as huge threats to birds lacks strong data and support, and often contain lots of potential biases/uncontrolled variables. I agree with him on many of these points, however (not to be anti-feline or anything, but..) I do know a rather unique example that involves both flightless birds and an isolated island situation, in which feral cats have been heavily implicated in their near extinction (after other initial causes of population decimation).

Professor Tantillo talked about how Fitzgerald & Turner drew the conclusions that cats on islands tend to prey more frequently on birds than do cats on continents (see page 166 of Dennis Turner's book, Domestic Cat: The Biology of it's Behavior). This example I'm about to discuss is in keeping with their conclusions, as it is about feral cats on very isolated islands, but I just wanted to share it because I think the flightlessness aspect adds a great facet to the feral cats vs. birds debate. (And it should also be taken into account because regardless of the extremely unusual qualities of this parrot, a bird is a bird is a bird.)

Conservation officer Daryl Eason feeding a Kakapo.
The Kakapo bird (Strigops habroptilus), also known as the owl parrot, is a large flightless parrot that is  nocturnal, like cats. They can climb trees and 'parachute' down using wings for balance and breaking, but primarily stay on the ground. They are suspected to be the oldest bird species, evolutionarily speaking, that is in existence today. They are almost entirely defenseless against predators such as cats because they evolved on New Zealand, which actually contained no mammals (except two species of bats) for millions of years. Their only predator was the giant eagle, which also went extinct, giving them no reason to evolve any defenses against predatory mammals.. The Kakapo once numbered in the hundreds of thousands. but after the arrival of humans (of course, who else?), much of their habitat was destroyed, they were hunted for food and feathers, and various predatory mammals were introduced. Humans eventually slowed down on habitat destruction & hunting about 150 years ago, leaving Kakapo populations significantly smaller, but still at a maintainable number with the removal of human pressures. Predation from introduced mammals still continued from stoats and feral cats, leading to a nearly complete extinction of the Kakapo.

In 1970 they were declared entirely extinct, but in 1974 two males were discovered in Fiordland. In the next four years, 16 more males were discovered, which still qualified the kakapo as extinct as there were no females. Finally, in 1977 around 200 birds were found on Stewart Island (a relatively uninhabited island in Southern NZ that was free of stoats but filled with cats), with the first females seen in nearly 100 years. Extensive research was performed in the next 4 years, where it was determined feral cats had become the main predatory threat. Admittedly, there are numerous variables/biases that come into play on this issue as discussed in class, since cats are certainly not the only factor affecting Kakapo population numbers. They have very low fertility and reproductive rates as they take 9-11 years to reach breeding age, and are also entirely herbivorous and will postpone breeding until good seed production years where they are certain to be able to raise chicks. There are also still pressures from other predators such as polynesian rats. However, when the Stewart Island population was fitted with radio-transmitters and monitored by researchers, it was found over 50% of the adults were killed within 12 months by feral cats, suggesting them as the primary threat.

Alarmed by the high death rates, in 1982 the NZ Wildlife Service was brought in to eradicate the feral cat population on Stewart Island. Initially it worked well, dropping predation rates from ~56% to nearly ~0%. This ultimately failed as cats quickly reoccupied the area and death rates went back up, so they finally relocated the remaining 61 Kakapo to three smaller cat-free islands. The NZ government stepped in and over the next few decades began implementing a Kakapo recovery program which has been fairly successful. The IUCN red list of threatened species's most current population size from 2009 states the total number of post-breeding season Kakapos left is 124, and of those, ~55 are mature adults.

So.. what do you think of this particular example of cats versus birds? Do you agree with the steps they took in re-establishing the Kakapo population? How sustainable is this path if the Kakapo still can't deal with predatory mammals? Is eradicating feral cats from the area justifiable to preserve this species of birds? Or are these birds just evolutionarily slow and haven't successfully adapted/deserve to go extinct?

Note - If you want more information, all my information was taken from sources that were hyperlinked to throughout this post, as well as you can take a look at this extensive list of kakapo related scientific publications.

Monday, April 16, 2012

Non-native species

Here is a recent article on judging non-native species by their origins:

The Baby Seal Issue Today

Today highly recognizable organizations like PETA and the International Humane Society still see Clubbing seals as a battleground. There has been laws prohibiting the clubbing of "white coat" seals in 1987, but bigger grayer seals are still up for grabs once a year. These baby seals, as stated in class grow up to be bigger seals that deplete fish stocks making it hard for fisherman to make a livelihood and support their economy.
Recently Ke$ha has turned her infamy into altruism. She has become the International Humane Society's first global ambassador, spreading her message "Canada's Club Scene Sucks." Ke$ha even made one of those cameos where her voice is backdrop to a slideshow of cute baby seals wiggling around helplessly. The cameo gives no mention or consolation to the fisherman locals that this ban would directly affect. She proposes that until Canada bans all seal killing, Protestors will not eat Canadian sea food. There's even an phone app called "Protect Seals" which will tell the user if a restaurant is seal friendly or not.
It's good to see Ke$ha trying to use the fame she has collected from eating beards and puking glitter for a good cause, but it saddens me that this ad might generate more support than an ad created by scientists.

Friday, April 6, 2012

Great Sequoia in Ithaca

While searching for the location of the local redwood tree. I found the great sequoia (Sierra redwood) that is located in downtown Ithaca. Although Sequoias can successfully grow in the northeast, they typically do not surpass  heights of 100 ft tall (compared to the usual 200 ft in  Sierra Nevada Mountains in California). It is interesting because although the tree is able to grow, the health of it is questionable. The unfavorable seasonal changes are most likely responsible for the unhealthy nature of the tree as the top is clearly dying.

Thursday, April 5, 2012

The day Niagara Falls dried

While today marks the anniversary of the only natural stoppage of the Niagara Falls flow, in July 1969, a team from the U.S. Army Corp of Engineers managed to divert the flow of water from Niagara River away from the American half of the Niagara Falls for several months with an artificial dam. This colossal effort allowed them to study the composition of the riverbed and strengthen a number of faults so slow the inevitable erosion of American Falls. Unfortunately for those of us who love when horses parade, unlike in the 1848 dry-up, no horses were paraded across Niagara Falls in 1969.