Another rare bird sighting

On Thursday last week I was fortunate enough to spot a particularly rare bird, the Australsian Bittern or matuku (Botaurus poiciloptilus). Along with the matuku I also had a brief sighing of a Fernbird, the topic of a previous post.

The matuku is a large wetland bird (it was much larger than I expected it to be) native to Australia and New Zealand. It is, like so much of New Zealand's wetland biota, in decline because of clearing and draining of wetlands for farming. According to the IUCN Red List the matutku numbers fewer than 1,000 individuals in Australia, and an estimated 580-725 individuals in New Zealand according to a report from 1980. That means that there are less than 2,000 individuals left placing it on the IUCN 'Endangered' list. Interestingly, however, the 1980 New Zealand estimate is possibly an underestimate because much of the habitat suitable for the matuku is on private land. That means that population counts have excluded these areas which may harbour many small populations. This possibility provides some hope but unfortunately the discontinuous, fragmented nature of wetland habitats in New Zealand is problematic.

The issue of habitat fragmentation has long been known be a significant threat to biodiversity. In a effort to remedy fragmentation, many people advocate the use of wildlife corridors or green belts. Interestingly, despite the pragmatic assumption that corridors are 'good' there is apparently little evidence that large corridors (over one mile) are, and if they are, what is 'good' about them. A couple of conservation biologists are hoping to answer this using a global dataset of large, long-term corridors. If you know of any potential useful sites (see the link for criteria) you could win cash for suggesting it as a study site.

A bird with a plant name! How appropriate.

I think given my sporadic posting due to work in the field (no complaints here) I am no longer going to kid myself with rigid nomenclature for grouping posts. What I mean is that I am relaxing the (in fact already have) "Bird of the week" and "Quote of the day" posts. Despite this I will keep up with doing posts along the same lines without the strict time frames.

From here

I begin this new series of "not of the weeks" with a bird one, and given that this week was host to World Wetlands Day a wetland bird seems appropriate, and as the title suggests the bird has a plant name. According to Wikipedia early settlers called it the 'swamp sparrow' due to colouration (see pictured) and its typical habitat, Kōtātā or Mātātā  by maori. It is now commonly called the Fernbird.

 The Fernbrid (Bowdleria punctata) is a monotypic species (i.e. the only species in its genus) in the Locustellidae family although Fernbird collectively refers to a species complex of fives subspecies. Each subspecies is native to a single island or island group: North Island, veleae; South Island, punctata; Stewart Island, stewartiana; Codfish Island, wilsoni and Snares Island, caudata. Despite their widespread distribution Fernbirds numbers are generally quite low. This is due overwhelmingly due to habitat clearance and their relatively high habitat-specificity. As I have already mentioned, Fernbirds inhabit wetlands. Wetlands in New Zealand have declined because they have been cleared for farming particularly in the Waikato and southern regions of the North Island. What habitat that does remain is often in heavily modified pastoral landscapes. Yet, despite this, Fernbirds remain locally common in areas where habitat remains. This is particularly evident in low-fertility manuka mires or pahiki that are not suitable for agriculture. My colleague was fortunate enough to see several Fernbirds this week in just such habitat.

I tweeted today about being in some wetlands on World Wetlands Day but sadly I didn't see any Fernbird. I did possibly (yet to be confirmed) collect a regionally critical plant, Carex fascicularis which is quite 'cool' in a plant-geek way. In fact over the last few months i have been quite lucky to visit several places around the Auckland region looking at pockets of remaining bush, wetland and coastal cliffs and have found quite a few rare/endangered plants. But I think I will save the discussion on my recent escapades for another post.

Keeping up with the Railses: New Zealand's flightless rails

In a previous post I touched briefly on two species of New Zealand rail in the genus Porphyrio. As mentioned, the pūkeko is one subspecies (Porphyrio porphyrio melanotus) that belongs to a cosmopolitan species complex. The takahē (Porphyrio hochsetterii), on the other hand, is endemic to New Zealand.  In addition to these two extant species there is an extinct member of the genus, the mōho (Porphyrio mantelli), also known as the North Island takahē. The pūkeko and takahē are morphologically similar as would the mōho have been, which is what you expect given that they are congeneric (i.e. in the same genus). From fossil evidence we know that the mōho and the takehe were more similar to each other than to the pūkeko: the main difference being that the mōho had longer legs, was larger and was more slender than the takahē. The strong morphological similarity between the mōho and takahē led early taxonomists to classify them as two subspecies, Porphyrio mantelli mantelli  and Porphyrio mantelli hochsetterii respectively. Because all three species are in the same genus, we know that they share a common ancestor. Therefore, pragmatically we might expect that they all evolved from this common ancestor in New Zealand.

However, this expectation is not supported by both fossil and molecular (DNA) evidence. In the mid-nineties, Steven Trewick (note the link to his personal page is broken but this takes you to his lab website) undertook a study of New Zealand rails to determine their origins, evolutionary history and the relationships among them. What he found was somewhat surprising in regard to the mōho and takahē. Rather than sharing a common ancestor with an in-situ divergence event, the mōho and takahē were the result of two separate colonisations by similar volant ancestors—probably a species similar to the pūkeko. This evidence resulted in a revision of the two subspecies into two separate species as indicated above. It also raised some interesting questions regarding the evolution of flightlessness among New Zealand rails.

New Zealand has (including recently extinct species) a relatively high diversity of rails (18), about half of which are flightless. An interesting question that Steve Trewick and his research group are asking is why seemingly mobile, volant species evolve into flightless range-restricted species. This comes partially from the fact that the likely ancestors of the mōho and the takahē came from the same lineage as the pūkeko. Because birds are highly mobile - the pūkeko being a perfect example in this case the - gene flow tends to be high reducing the probability of speciation. In fact, there is little evidence for speciation among birds on islands. In other words, it takes a substantial barrier to stop gene flow in birds which reduces the probability of speciation. Yet there have been several independent rail colonisations in NZ with many resulting in a flightless species. To me this indicates that there is strong selection for rails to fly when necessary (i.e. in the presence of predators) but it is easily relaxed without predators. But the question of even rates of gene flow remains.

Double blog assault

Allison Campbell who alerted me to the integrated state schools that choose not to teach evolution through her posts here and here has taken a similar direction as I have in my post Blow by blow: part 1(see also here). Allison has lightened my load somewhat by commenting on section nine of the Ponatahi Christian School's statement on creation/evolution "[w]hat about archeopteryx?"  Many creationists see archeopteryx as some sort of silver bullet (among many others) to evolutionary theory. Allison does a nice job of showing how this the wrong stand to take.

A winner is crowned

Pūkeko (Porphyrio porphyrio melanotus) from wikipedia

Forget bird of the week, here is bird of the year as voted by the New Zealand public (truthfully it was 7851 of them). This year it was taken out by the humble pūkeko (Porphyrio porphyrio melanotus). The pūkeko is a common rail that inhabits swamps and wetland, often seen at motorway verges. Sadly this tendency to hang out next to the motorway results in a fair number of deaths by car. Interestingly (to me at least), the pūkeko is a subspecies that belongs to a species complex with a broad distribution. Collectively known as the Purple Swamphen, the complex consists of 15 subspecies found in Europe, southeast Asia, Africa, New Guinea, Melanesia, western Polynesia, Australia and of course New Zealand. The Purple Swamphen is truly cosmopolitan. 

A takahē (Porphyrio hochstetteri)from here

In addition to the pūkeko, New Zealand is home to eight other species of rail. There is also evidence from middens that there were another eight species of endemic rails. But, as I have mentioned in previous posts on New Zealand birds (here and here), the arrival of humans resulted in their extinction. One species that was thought to be extinct, the takahē (Porphyrio mantelli hochstetteri), was 'miraculaously' rediscovered in 1948 G.B. Orbell. Orbell found a small population of about 250 indivuduals in a remote refuge in the Murchison, Kepler and Stuart Mountains in Fjordland on New Zealand's South Island. Following breeding and relocation efforts, takahē are now found on four predator-free offshore islands as well as at their rediscovery site.

Given their close relation to each other, the pūkeko and takahē are similar in appearance. Both species are bluish in colour with bright red legs and bills. However, the takahē is stockier and has a heavier bill. Furthermore, the takahē is flightless whereas the pūkeko is volant (i.e. it flies), albeit reluctantly, which is typical among rails. As with many New Zealand birds, and island birds in general, flightlessness is common and evolves in the absence of mammalian predators or competitors.

For some more pictures of pūkeko and other NZ native birds check out Chthoniid's Wildlife Photography and for some takahē videos check out the Deparment of Conservation. Also look out for a follow-up post on takahē that will be a little bit sciencier (that is a real word) demonstrating how modern genetic techniques have helped us learn so much more about species distributions. There is a hint about it in the species name for takahē.

Return of the birds: the lazy parent

 Is this the return of the failed ‘Bird of the week’ posts? Who knows? I won’t commit to a weekly bird post given that the last ‘Bird of the week’ was over nine months ago. I will, however, endeavor to post more about birds at more regular intervals.

Taxonomy
Kingdom	Animalia
Phylum	Chordata
Class	Aves
Order	Cuculiformes
Family	Cuculidae
Genus	Chrysococcyx
Species	lucidas

  

Today’s bird is quite a charismatic bird in terms of its interesting life history/survival strategy. These birds are brood parasites which means that they lay their eggs in the nests of other birds. The bird is obviously the cuckoo, more specifically the New Zealand Shining Cuckoo or pipiwharauroa (Chrysococcyx lucidus). Shining Cuckoos are so called due to their burnished metallic bronze-green plumage. Easily identified by their aforementioned plumage as well as their distinctive high-pitched call, Shining Cuckoos are a relatively common species found inhabiting native forest, scrub, parks and gardens though out New Zealand. During winter they migrate to Solomon Islands and Bismark Archipelago.

Although brood parasitism is found among other birds, among fish and insects, cuckoos are certainly the most famous of the brood parasites.  This is most likely because cuckoos are typically interspecific brood parasites (i.e. they use other species as host parents).  The Shining Cuckoo’s usual host is the Grey Warbler. Brood parasitism is more common in Old World cuckoos (~56 species) than in Old World cuckoos (~3 species). All of the former are members of the same family as the Shining Cuckoo, Cuculide, and all are obligate brood parasites. This means that they are ‘obliged’ to put their eggs in someone else's basket. However, whose basket is the question.

Photo credit: Peter Woods taken from http://www.nzbirds.com

 One of the common strategies for cuckoos to get a host to sit on their eggs is to mimic the appearance of the host’s eggs. As mentioned previously, the Shining Cuckoo uses the Grey Warbler as a host. Therefore, under an evolutionary arms race scenario, the cuckoo would be under selection to produce better and better mimetic eggs and the host would attempt to counter this with some sort of anti-parasitism defence (note: do not interpret the scenario as teleological). We should therefore expect that a single species of cuckoo would have a singly host species. Interestingly, this is not always the case. Some species of cuckoos have several host species and the way they get this right is by having polymorphic eggs. This means that within a species of cuckoo, different individuals lay eggs that look different and mimic the eggs of a different host species. But how does this happen and why do some individuals have different eggs?

The first question you would need to ask is how the females know which species has eggs that look like their own, and the second one would be why do females lay the same eggs as their mother if they mate with a male born to a female of a different egg type. The first question is relatively straight forward. The female is likely to carry some sort of imprint from the song and appearance of her surrogate mother making it easier for her to identify a host when she needs to lay her eggs. This is particularly important in areas where the different host species have overlapping geographic ranges. The second question has a remarkable potential answer. In mammals, males carry one X and one Y chromosome and females carry two X chromosomes. In birds, however, females carry one W and one Z chromosome and males carry two Z chromosomes. It is therefore possible that the gene related to egg colour determination in cuckoos is carried in the W chromosome. Therefore, it doesn’t matter what egg type male was born from, it is only the female that matters.

Mimetic eggs are not the only way that cuckoos get away with brood parasitism. In some species the egg does not resemble the hosts’ eggs. How then does the cuckoo get away with it? Historically it has been suggested there might be lag in the evolution of the host such that there has not been enough time to evolve defenses or, the host is genetically constrained somehow and unable to evolve a defense. This means that the evolutionary arms race is in disequilibrium. A recent study of the Jacobin Cuckoo (Clamator jacobinus) and its host the Cape bulbul (Pycnonotus capensis) suggests that in this case it might actually be stable. This is an example of a non-mimetic egg host–parasite relationship because eggs of the Jacobin Cuckoo are almost twice the size of the eggs of the Cape Bulbul. Given this non-mimetic nature of the cuckoo eggs it would be easy for the Bulbul to recognise the imposter but the eggs are probably too heavy to eject from the nest and too thick to break open. Why does the Bulbul not just desert the nest in the presence of a cuckoo egg? Despite cuckoo eggs and/or chicks being present in the nest the author found that the fitness of the Bulbul was not reduced to zero. In other words some Bulbul offspring did survive to fledge in the presence of cuckoo chicks. Thus, if the Bulbul does abandon the nest its own chicks would die, effectively reducing its own fitness. This work is interesting because evolutionary lag has tended to be the typical explanation for the non-mimetic phenomenon among cuckoos. It also indicates the importance of questioning ideas carefully in science and not sticking to the status quo.

Science journalism?

A recent paper published in Frontiers in Ecology and the Environment (Clements et al. 2011) and subsequent press releases in New Zealand has resulted in a some public backlash. The paper proposes a new index for assessing the extinction risk of a species called SAFE (species ability to forestall extinction). In the paper the authors tested the strength of the SAFE index at predicting the most commonly used species threat measure, the International Union for Conservation of Nature (IUCN) Red List, and found it to perform better than other currently used measures.

The SAFE index is really quite simple. It takes into account two things, the total number of individuals in a species across it's entire known range and, the minimum viable population (MVP) of a species. The minimum viable population is the lowest number of individuals a population needs to sustain itself. A few years ago a cross species review of MVP and found that on average MVPs are around 4169 individuals (Traill et al 2007). The importance of this with regard to extinctions is obvious. If a species population size drops below this minimum, the chances of extinction are greatly increased. See I told you it was simple.

Photo credit: Shane McInnes, winner of The Worlds Rarest Birds photo competition

However, the backlash in New Zealand about this work was largely from ill informed people who have a chip on their shoulder. What chip you ask? Well it so happens that the authors of the SAFE paper are based at Australian institutions. So what? Well the crux of the story stems from the misrepresentation of the work and how it can be applied in a real world situation. Professor Cory Bradshaw was one of the authors who worked on the paper and talked about the work on radio here in NZ. There were also some news articles, one entitled 'Let the wonderfully wierd kakapo die--scientist' specifically got me riled up. The kakapo (pictured above) is a very unique bird in that is a flightless, nocturnal parrot, the only one of its kind in the world, but like so many NZ birds, it is endangered. And according to the SAFE index, with only 131 individuals of the species left, it has little chance of being saved. Luckily there are a huge number of dedicated people, both paid and volunteers, who are trying to get this bird back on it's feet. What Corey Bradshaw had to say was what people hated. He said that the massive expenditure on saving a single species that fell short on the SAFE index is unjustified because, where financial resources are limited, this happens to the detriment of countless other species. The other species may not be endangered but could be on the verge and thus excluded from the conservation effort. Therefore, by the time we realize that these species are becoming rare it may be too late, one because we spent too much money on a single species and don't have much left, and two because they may already be below the MVP threshold. 


You could go and read some of the comments on the news article but I have picked out some of my favourites:

This one is priceless for a couple of reasons. Firstly they cite positive as people who are slandering Corey Bradshaw, and secondly he talks about Darwineans. I think what he means is darwinians, but I have no idea what he means by it, particularly when he talks about saving money etc.

Glad to see so many positive (save the Po) comments, but am surprised at the number who agree with the Aussie! NZ has saved a bird before, and hopefully we will do it again. To those of you "Darwineans" who are against "wasting money" saving it....think of all the money we waste trying to save other humans?? Is that a waste too? Should the NZ government let nature take its course next time you have a treatable illness or injury?

 Another classic. I love how she  calls him a "so-called 'scientist'". And then goes on to attack him because he is Australian. If she had not just read the crap title of the article and bothered to find out about the source material she would ave realised two things. One, that Corey Bradshaw is a "real" scientist who is highly published and respected in his field, and two, that he is in fact Canadian who now lives in Australia. Additionally, he did his PhD in New Zealand.

Please everyone, don't give this so-called 'scientist' another minute of our time. BUT, I guess if we don't, he will think "yeah, no one is commenting about my statement" so he'll think we really don't care about saving our lovely little kakapo. wrong !!!! Keep your Aussie BS to yourself....

 Comments about being Australian were really common. Here's a couple more. These ones are the most ridiculous. Real geniuses!

As many others have said, how about the Australians keep to their own country?! Australia has their own problems to watch out for!

Typical comment from an Australian i mean they have a history with there Native people as well.

The worst part about this is obvious slant the media took and by having a title like it did, peoples minds were made up for them before they actually had any understanding of the topic.

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Clements, G. R., Bradshaw, C. J. A., Brook, B. W., & Laurance, W. F. The SAFE index: using a threshold population target to measure relative species threat. Frontiers in Ecology and the Environment, preprint.

Traill, L. W., Bradshaw, C. J. A., & Brook, B. W. (2007). Minimum viable population size: A meta-analysis of 30 years of published estimates. Biological Conservation, 139(1-2), 159-166.

Light without flight

Stephens Island wren (Traversia lyalli) drawn by John Gerrard Keulemans

 This week's birds comes once again from New Zealand's extinct passerine birds fauna. I have previously posted about the heaviest bird capable of flight, the kori bustard. Today I introduce you to the Stephens Island wren (Traversia lyalli), weighing around 20 grams and the lighest  bird that is known to have been flightless. It was also one of only three known flightless passerines, all of which were island birds. Were, because sadly they are all extinct.

Flightlessness in birds is common on islands and is an artefact of an evolutionary history devoid of typically mammalian predators. This is evident in New Zealand which has the greatest number of flightless bird species than any other landmass. Subsequently, it is flightlessness that contributes significantly to predation vulnerability and ultimately extinction, another common occurrence on islands in recent times. And it is exactly this which led to the demise of the Stephens Island wren.

Stephens Island, or takapourewa is located at the northernmost tip of the Marlborough Sounds on the South Island of New Zealand. Up until the 1890s it was free from human impact and pests, and had become the last remaining outpost for the Stephens Island wren.  This changed when it was decided that the island would make a perfect place for a lighthouse. The remoteness and untouched nature of the island is beautifully highlighted by Prof. Richard Holdaway who said that it would have been like stepping back in time. Unfortunately for the little wren species, that moment marked beggining of the end. On such a small island, only 1.84 sq km, there is not much place to hide if you are a bird that can't fly, and especially from a cat. The lighthouse keeper, Lyall (from who the wren gets it's species name) had just that, a cat! According to legend Tibbles the cat made short work of the little wren and has been credited with single pawdedly wiping out an entire species. This of course is not true since the bird was previously found on the mainland. There is an historical account of what did happen on the wiki page.

One last thought I will leave you with is this question; if Stephens Island is 3.4km away from the mainland and the Stephens Island wren was flightless, how did it get there?

Which is which?

I admit that bird watching is not a particularly 'cool' hobby, but who cares? As long as you are doing something that makes you happy. As I have said before, I am enjoying birds more and more recently. But, like so many things that are either new to you or that you haven't done for a while, it can be pretty frustrating. I tried skateboarding again a couple of years back after an eight year hiatus. Not only am I older and more weary of getting hurt, but my body just didn't do things the things were second nature a smoothly as it used to. The same goes for bird watching. It takes practice and patience.

Fortunately however, the guys over at the Cornell Lab of Ornithology made the video shown below to help out. Identifying birds is more simple than it appears. As they point out there are four parts to identifying birds namely, (1) Size and shape, (2) colour pattern, (3) behavior and, (4) habitat. This video covers size and shape and the importance of comparison. The best part is that the diagnostics are universally applicable to birds everywhere. Get yourself some binoculars, a good field guide and, have a go. It is a relatively low cost hobby (although the hard-core birders often spend small fortunes on ocular equipment) and you get to spend time outside, a rarity these days.

Grow a beard and get more sex

A new study, reported here on Science Daily, on the factors that lead to reproductive success of male great bustards (Otis tarda) has suggested that males with more, and longer 'beard plumage' have a greater chance of reproducing. The reasons for this are suggested to be two fold. Firstly, the more 'beard' a bird has, the older and heavier the bird is, hence males who have less 'beard' will not challenge more 'beardy' males for fear of defeat. Secondly, females prefer the more 'beardy' males, seemingly because of their size. There you have it, chicks dig beards. I must be weak because I am 28 and still can't really grow a decent beard. I must have tricked my wife with some other display of virility, and I'm a pretty good cook.

A pair of great bustards. Note the plumage on the chin of the male (standing). Picture courtesy of Wikipedia.

This is worth tweeting about

Found this cool site on the New Zealand Department of Conservation's website. It's a collection of some native NZ bird calls, including the morning chorus recorded in the Abel Tasman National Park where I went tramping over New Years. The bird in the foreground is a bellbird/korimako, pictured below. We saw plenty of them while we were tramping.

A pair of bellbirds

Clever crows

Photo: Jolyon Troscianko, University of Birmingham

Humans initially considered themselves distinct from other animals due to our ability to make and use tools. That was until Jane Goodall observed chimpanzees making using stalks of grass to "fish" for termites. But, it is not only primates that use tools. There are a surprising number of animals that use tools including, elephants, dolphins, otters, birds and octopuses (it's acceptable to use either octopuses or octopodes, but NEVER octopi).

Probably the most proficient and innovative tool maker of all is a bird. The New Caledonian crow (Corvus moneduloides) surpasses many with it's almost unbelievable ability to make and use tools. Watch the video below that I saw on Jerry Coyne's blog. After seeing the video I was amazed and did a little more research into this brilliant bird. I found this cool site from a research group at The University of Auckland, just across the road from my university. It has loads of videos and pictures, and for those who don't mind a bit reading, pdfs of some of the research articles they have published.

Do you love birds?

 Found a neat social networking site for bird lovers. WeLoveBirds.org is a site hosted by the Cornell University Lab of Ornithology. There are plenty of photos, videos and discussion forums about bird IDs etc. '. It's a place where you can interact with other bird watchers and seriously bird-geek out--and not be judged.

Birdwatchers. Photo courtesy of Wikipedia

Fishing heron

Saw this on Jerry Coyne's blog. It is brilliant. Birds rule.

Got another clever bird video, but more about that later.

My kori bastard photo and more

Here is a couple of shots I got of a kori bustard in the Kruger Park along with another photo that would come close to being the highlight of the trip.

Kori bustard (excuse the poor resolution, the camera was zoomed to the maximum)

Same bird as above

Spotted this guy with the rest of the pride just seconds after photographing the kori bustard

He barely noticed we were even there

Weekly bird?

There are plenty of other bloggers who have particular interests that do a weekly, or daily for the more dedicated, post pertaining to that particular interest. Given the title of my blog, birds are one of my interests. As a child in South Africa my family and I would go to the famous wild life reserve the Kruger National Park but, unlike most people, we would spend most of the time during a week long trip looking at, and identifying birds. Of course we were interested in the other animals but it was the birds that we, at least my dad and I, were fascinated by. Since moving to New Zealand 10 years ago my dedication to bird watching has waned a little. More recently however, I have become increasingly interested. Partly because of my studies and, partly because of a recent trip to South Africa for my brothers wedding, which included a trip to the Kruger Park.

It is from the trip to the Kruger Park that I got my inspiration for the first of what I hope to be a weekly post about my bird of the week. I might even consider a weekly tree/plant given the other part of my blog title. In fact I have posted this orchid in the past week.

This weeks bird is the kori bustard (Ardeotis kori). Unfortunately I am writing this from my desk and university so I don't have any personal images of the bird but I will post the one I took at the Kruger Park tomorrow. Until then see the image below.

A kori bustard with bee eaters riding on it's back grabbing insects disturbed by the bird (photo credit: www.birdfinders.co.uk)

The kori bustard is a big bird with males weighing up to 20 kilograms. The wikipedia article refers to a report of 35 kilogram bird but, this is unverified. The most interesting thing about these birds, is that despite their big size and weight they are still able to fly. This makes them contenders for the heaviest birds capable of flight. Click here for a video of bustard taking off and landing. In general however, they prefer to keep their feet on the ground and are almost always seen walking across savanna in search of food such as lizards, insects, berries and seeds.

There is an excellent article (Lichtenberg and Hallager, 2008) with really in depth information about  kori bustards decribing 63 individual behavioural characteristics. It can be accessed by clicking here.