Tuesday, July 1, 2008
Penguins in the News
A couple of days ago the Mad Natural Historian sent me a link to this research project. It is a quite interesting article on how to tell one jackass from another. Really. Usually I would not care to tell one from another but in this case they are penguins from South Africa so the story is more interesting.
It seems that the researchers are using recognition software to examine the pattern of breast bands on African (or Jackass) penguins (Spheniscus demersus) to track individual penguins. Tracking individual penguins for research has always been problematic. Placing traditional bird bands on penguin legs resulted in severe problems for the penguins because the band rested on the top of the foot when the penguin was out of the water and rubbed the top of the foot raw. The next best place to mark a penguin is a flipper band. These seem to work the best but have also caused some concern about survival due to potential changes in energetics when penguins are swimming with these bands around the base of their flipper. Results of research has varied on the impact of these bands on penguins and it is probably fair to say that they do affect penguins but the the extent of the effects are debatable.
Anyway, this project aims to use video cameras and software to track individuals in large colonies and claims to be pretty successful. I like the idea of limiting impacts to study subjects and this seems like a rather good way to get survival data but I guess I am skeptical about the utility for some of the research we need to mark penguins for. If this works for young of the year penguins and is able to track them as they molt into adult penguins then I will start to see a greater utility in this method because one of the most important pieces of data gained from traditional banding studies is how many young penguins survive to return to breed. I also question the utility of this methodology for most other penguin species which either do not have such large individual variation in plumage or live in much more remote areas with little tech support.
The other article is from the latest issue of BioScience. The article, Penguins as Marine Sentinels by penguin researcher P. Dee Boersma is an great overview of the current state of affairs for a number of penguins species, but in particular the Magellanic Penguin which she has investigated for many years. The article is spot on with the problems many penguin species are facing but reaches a bit for impacts on the species Dr. Boersma is less familiar with. She uses her many years of research to point out problems with changing environments for Magellanic Penguins but then gives the same level of importance to two singular events she witnessed while traveling in Antarctica. One was a sudden breakup of a traditional nesting area for Emperor Penguins which resulted in the loss of the cohort of chicks produced that year and the other was a year with particularly heavy snowfall that resulted in the same impacts on penguins breeding on the Antarctic Peninsula.
Chinstrap Penguin Colonies on Clarence Island, November 2007.
I was counting penguins on the peninsula that same year and I agree that, much like this past year, large amounts of snow do wreak havoc with the reproductive success of many penguins on the Antarctic Peninsula. But penguins are long lived birds and have adapted to an extremely variable environment by living long enough to ensure that at least one generation of chicks they produce will survive to breed. Single observation points are seldom used in science to justify patterns and Dr. Boersma uses these single observations to make claims about climate change impacts on penguin populations. These are interesting anecdotes that illustrate problems faced by penguin in one year but the peninsula has been warming annually and these impacts do not occur each year. Dr. Boersma also makes some logical claims that warming should result in increased snow and rain during the period when penguins are nesting but provides no data or references to back up that claim. It is also quite possible that in most years the warming trend actually melts snow faster in the spring resulting in more open ground for the penguin to build their nests on. Data I collected at Palmer Station many years ago suggested that this pattern was more consistent than years where snow impacted breeding success. The real culprit for declining penguin populations is more likely the loss of sea ice and disruptions in somewhat predictable krill concentrations near colonies when penguins fledge. As krill populations are reduced due to changes in the marine environment related to sea ice extent, young penguins learning how to locate and capture krill have fewer krill to "practice" their foraging skills on and they simply die before learning to capture enough food to live. Those that do manage to learn have enough krill to survive but the overall population trajectory is downward due to decreases in chick survival. These reductions impact small colonies greater as there are fewer penguins produced in small colonies to start with and when young penguins return to their colonies to breed they more than likely move to larger colonies if their natal colony has gotten too small. Small colonies in particular are susceptible to predation from skuas and often fail to produce any chicks. If recruiting penguins return to a colony with no reproductive success, the cues they probably use to assess the "health" of that colony are gone and they look for other, larger colonies to breed in, further exacerbating the decline of the small colony to extinction. This has nothing to do with increased snowfall limiting reproductive success but everything to do with climate change. The impacts just happen at different places in a penguins life cycle.
She does call for continued monitoring of penguin populations in 41 penguin "hotspots" around the southern ocean and I am glad to say that I am part of the only long-term monitoring project that works throughout the Antarctic Peninsula to do just that. Oceanites has been monitoring penguin populations for over 14 years and has documented the long term changes that Dr. Boersma advocates for all the penguin hotspots she had designated.
Counting Gentoo Penguins
Overall this is a good article that outlines problems facing most penguin species today and provides some wonderful summaries of Dr. Boersma's research in Argentina but it reaches a bit when she ventures into discussions on other species she is less familiar with.