Breeding seabirds

Just back from the island again and more developments to record.

The Brown Noddy (Anous stolidus). In my last post (Nature Notes 4 of 26th May) I recorded that there were currently a lot of white tern chicks in evidence around the island. The first thing I noticed on arriving on Denis on Thursday was the rapid and widespread onset of nest building amongst the island’s Brown noddies. The pathway leading up to the main hotel building was alive with the squawking refrain of the birds from the crowns of all coconut trees. The Brown noddy builds a simple though often rather large and untidy platform of twigs, casuarina fronds and sea weed at the base of the palm leaves where the large stem forms a natural gully where it joins with the trunk of the tree. The coconut trees in the hotel garden are particularly busy with many of the trees harbouring 3 or 4 nests. This density is not reflected elsewhere with trees typically having only 1 or 2 nests per crown. I am not sure why this should be, but I am inclined to think it is linked to the spacing of the trees and the lack of other canopy which provides easily navigable flight paths for the birds to access all the suitable nesting niches a tree has to offer. This coupled with the relative shortness of the trees in this open environment means they are sheltered from much of the wind by the hotel, readily accessible and yet secure – making them ideal for nesting.
I spent a while trying to get some photos of this nest-building activity – one bird would remain on the nest platform whilst the other would fly back and forth gathering and bringing material which it would then give the other which would incorporate it into the nest structure. The noddies were particularly busy collecting nesting material on the beach crest around the hotel where the last high-tide had washed up a lot of suitable material. The arrival of the bird bringing material would initiate another burst of harsh calling between the pair including bouts of their distinctive, bond-forming nodding behaviour which gives the birds their name.

White-tailed Tropicbird (Phaethon Lepturus). I also reported in my last post the return of the tropicbirds to the nest site that successfully produced our first confirmed fledging from a ground nest for this species. I checked on the nest again on Saturday and the bird was still present presumably incubating. The nest site is immediately adjacent to the path and I hence decided to cut a palm leaf and lean it against the Casuarina trunk thereby screening the nest from passersby on the path and thus hopefully reducing somewhat the stress on the birds – I will provide feedback periodically. We also now have a fourth confirmed ground nest on the island. This nest north of the runway and behind the staff quarters at “L’Allee Coco Rouge” is cosily placed amongst some old logs and currently contains a well-developed chick (see photo in sidebar).

I have been following the development of Denis as a seabird colony in detail on this blog. It is of significant interest to record the recovery of seabird populations following the cat and rat eradications in 2000 and 2002 respectively and Denis is making good progress.
The island currently supports breeding populations of: Brown Noddy, White terns (Gygis alba), White-tailed Tropicbirds and Wedge-tailed shearwaters (Puffinus pacificus). The island also supports a large roosting population of Lesser Noddies (Anous tenuirostris) which we hope may in time develop into a breeding population and of course the island is actively undertaking a project to re-establish a Sooty Tern (Onychoprion fuscata) colony.

Nature Notes 4

Notes from my last visit to the island and quite a few items of interest to report:

• Magpie-robin news – firstly and sadly I have to report that we appear to have lost the poorly female that I reported on in my post of May 19th. There being no flight on Wednesday of last week the antibiotics, syringes etc… could only be taken to the island that Thursday and Catherina has not sighted the bird since Wednesday and we must now fear the worst. We do now however have a fresh stock of antibiotics with a long shelf-life on the island being kept in the fridge in case it should be needed in the future.
• Flycatcher news – on a positive note our first flycatcher fledgling (see post of 21st April) appears to be prospering and there are currently 3 other breeding attempts ongoing in other territories.
• White terns (Gygis alba) – we have been having a prolonged period of very hot weather in the central archipelago. There is typically a period of 3 or 4 weeks in April/May when the wind drops and the weather is very hot and dry before the next season establishes – but this year it has been going on for a couple of months. A change in the wind can effect water temperature and prevailing currents which in turn impacts upon the availability of the small fish that sea birds depend on to feed their young. The impression on the Denis at the moment however is that food is in abundance as we are experiencing a marked surge in the number of young white terns on the island. Let’s hope that food availability remains sufficient to see them through to independence.
• White-tailed tropicbirds – I am delighted to be able to report that the site that produced our first confirmed tropicbird fledgling from a ground nest since the eradication of rats in 2002 is once again occupied by the female. Those regular readers of the blog will recall how I followed the development of “Tina” last year in detail on this blog and was delighted to report her successful fledging in the week of Christmas. Well her mother is now back on the nest site and possibly already incubating another egg. Another great benchmark in the recovery of the island’s ecosystem!
• Greater Crested terns – birds are still to be seen each morning at Pte Mme Guichard and then in the afternoon on the sandstone outcrops just off the southern coast. There are currently nine birds in residence.

Observations on the Blue-cheeked bee-eater (Merops persicus)…

Now into the fourth week of May and the Blue-cheeked bee-eater is still a common sight on Denis. My impression is that numbers have increased again over the last month with perhaps 30 or more on the island. Following the major influx in November when some 500 or so birds descended on the island. I recall watching literally hundreds hawking over the runway in the evening at the end of that month. The island was alive with these bright green birds with, so it seemed, practically every prominent perch along the paths occupied by yet another bird and their “trilling” call to be heard everywhere.

Numbers rapidly dropped after a few days but a few have been present ever since. During April the numbers went up again presumably as birds were passing through Seychelles this time on their route back north to their summer breeding grounds in southern Asia. Coming to the island on May 21st I frankly didn’t expect to see any as I presumed they would have all flown North by now – but the first bird call I heard as I got of the plane was that of a bee-eater and I could see 4 of them hawking over the beach by the runway. Later that day I saw several more along the east coast at Belle Etoile and more again around the hotel complex and late that afternoon I observed ten to a dozen feeding over the runway.

The next morning I went to photograph the beach outside the main hotel complex as part of a long term study of beach movement and erosion that I have been doing since 2005 when I encountered another bee-eater hawking from a perch on a fallen tree branch that had been washed up. I have learnt over the last 6 months that the bee-eaters are very alert and rather cautious and generally won’t let you get at all close before moving on. This bird however was otherwise occupied as the inshore breeze early that morning appeared to be channeling insects along the coast right past its vantage point. It was therefore very busy securing its breakfast and seemed little concerned with me.

Every 30 seconds or so it would dart of its perch in pursuit of an insect catch it and then stunt and turn in amazingly tight arcs to return to its original position to await its next passing snack. Over the next half-hour I utilised each of its forays to edge incrementally closer to its perch then as I got within about 10 -12 metres the sun came out from behind the clouds and giving good light to photograph the bird and capture the stunning colours of its plumage (see side bar). I was absorbed by this process; with every flight I got a few inches closer and so I believed each set of photos would be that little better than the one before.

I was then fortunate enough to observe some very interesting behavior. The bee-eater returned to its perch with a very large prey in its beak aptly enough it was a large bee – a male carpenter bee in fact.The bird then proceeded to beat the bee against the branch giving off a surprisingly loud “Thok, Thok, Thok” drumming noise as the insect’s exoskeleton hit the wood. Finishing off this bee was not to be an easy task however, despite this vicious beating! One such hit served to dislodge the bee from the bird’s beak and it was off… in a low careering flight over the sand away from its would-be captor. The bird was immediately in pursuit and in the space of 20 feet had re-captured its prey and then promptly returned to its perch to continue the drumming! This scene played out four times. Four times the bee escaped and flew for its life, four times the bee-eater shot after it recaptured it and returned to its post to continue the assault. It was fascinating to watch the blend of beauty, savagery and efficiency embodied by this stunning bird. The blows were administered by a severe whipping action of its head and neck a photo in the sidebar shows how the bird has actually turned its head 180o in order to imbue the whip-lash action with optimal force! Eventually the bee was subdued and then promptly consumed – the whole process from first capture to swallowing had taken a good 4-5 minutes.

The bird then continued with its business and I with mine edging progressively closer in search of that “perfect” photo and then suddenly it was gone. I waited for another 5 – 10 minutes in the hope it may return but it had flown off south-west down the coast doubtless to find another strategic point to continue its hunting.

I was very pleased with my morning’s “work” and I think – and I hope you agree - I was able to catch some good images of this truly wonderful bird.

Sooty tern (Onychoprion fuscata) project – year 2

It’s getting round to that time of year again! I have just received a shipment of new models (see photo in sidebar) so we can increase the density of models in the trial area this year. These models are closer to the actual size of the Sooty tern and are in fact magpie models that have been re-painted to appear like Sooty terns. When Denis was first discovered in 1773 it hosted very large seabird colonies including a large population of Sooty tern. Human impact on the island over the next hundreds years was very extensive and it is likely that the ground nesting sea bird colonies were extirpated within that period.

The environmental management plan for Denis has set aside the southern portion of the island for restoration to as close as possible to how it was when first discovered. The attempt to re-establish a colony of Sooty terns on the island forms part of this initiative.
The project commenced last year (see my posts of 2nd July, 21st September and 13th October 2008 for more information) with the preparation of the habitat area and the trial of different habitat and stimuli combinations including 2D and 3D models and the broadcasting of colony noise from loud speakers.

The first year of work and its structured approach allowed us to learn a good deal about the preferences of the birds and the trial area will be set out this year to reflect those findings and we are optimistic about the potential for 2009.

We are working with Dr Chris Feare who is a leading ornithologist and has been working on Sooty terns in Seychelles for many years. Chris will be arriving at the end of this month along with a couple of volunteers who will assist with the monitoring of the scheme this year - as well as undertaking other work.

I will report regularly on the project and its progression – success is by no means guaranteed but we are again breaking new ground here on Denis Island and should we achieve our objective it would represent another world first for the island - so do keep checking back for news on the Sooty tern project over the coming weeks…

A poorly Magpie-robin…

I received earlier today a call from Catherina on the island telling me that she had sent an e-mail with photos of an adult female SMR that was showing signs of ill-health. The posture, plumage and behaviour of the bird were not good and furthermore its droppings were liquid.

E-mail communications followed with Rachel Bristol and I then spoke with Dr Melanie to the vets department on Mahe. It was decided to get a broad-spectrum antibiotic that could be administered by injection to the bird. So I then went to the vets department purchased a bottle of Oxytetracycline and the smallest syringes and needles available.

The treatment entails capturing the bird and injecting 0.1ml into the bird’s muscle tissue and repeat in 3 days or so. This method has been used successfully previously on SMRs. So it is to be hoped that this problem is based upon a bacterial infection and that the treatment reaps benefits.

Unfortunately by the time I got the call from Catherina it was already too late to catch the plane and there being no flight on Wednesday we will not be able to get the medicine to the island before Thursday – hopefully it won’t be too late.

The tetracycline has a long shelf life so we can keep it in the fridge on Denis for about a year and use it on other birds should the need arise.

Check back regularly for news on our poorly magpie-robin.

The Seychelles Flycatcher (Terpsiphone corvina): whiskers, “hair-dos” and mimicry…

In my post of 9th April I wrote about the whiskers clearly evident on the faces of both male and female flycatchers (Terpsiphone corvina) and postulated on what their purpose might be. Whilst drafting that post I spoke to Rachel Bristol, Project Officer on the Flycatcher project. We talked about the whiskers and Rachel also commented on head plumage of the birds referring to it in her inimitable style as a “spiky hair-do”. Rachel subsequently sent me a wonderful photo of a male flycatcher in hand which clearly illustrates both features (see sidebar).

Then after her last visit to Denis, Rachel called to update me on her findings and mentioned something new of real interest namely that the Seychelles magpie robins (Copsychus sechellarum) in some territories had begun to imitate the song of the Flycatcher.

I have in the past written about the ability of Mynah birds to mimic the calls of the Seychelles magpie robin on Denis. The Mynah is a renowned mimic and I would not have been at all surprised if they had already begun copying the Flycatcher’s call and causing confusion in Rachel’s attempt to monitor the flycatchers on Denis. The Seychelles magpie robin is another matter and this is of particular interest because until the introduction of Flycatchers to Denis in November the two species had not co-existed on an island for a hundred years or more. This co-existence is therefore a new experience for the all the birds and also a time of great interest for ornithologists to see how the two species will interact. The feeding niche of the two species is largely distinct and their territories overlay each other on Denis without any evidence of negative interaction but the Magpie robins adopting the song of the flycatcher may conceivably lead to some confrontations in territories – at least in the short term

I was involved with the transfer of Magpie robins to Cousine Island in 1995. The overall population was much lower back then and the habitat on Cousine despite my efforts over the preceding year or two was still limited for the species. As such a very precautionary approach to the introduction was undertaken - two young surplus males from Fregate were introduced to the island and latterly an old male which had been displaced from its territory on Fregate and following injury had been nursed back to health by hand. These birds were surplus and somewhat expendable and the intention was to see how they fared on Cousine before any precious females would be risked. (The birds did settle and the old one ended up fathering more offspring when females were latterly introduced). Initially however what was remarkable was the very limited song variety of the young males. One of them just continually repeating the same three note refrain until it would put one’s teeth on edge! When the old male was introduced however he had an extensive variety of tunes suggesting that birds acquire/learn new songs over time and are not born with a pre-programmed repertoire. This thought was re-enforced when the younger males began to expand their own tune list once the old male had been introduced.

Now here on Denis nearly 15 years later we have further evidence of the capacity of the Magpie robin to learn new tunes and styles.

Observations on the Seychelles blue pigeon (Alectroenas pulcherrima)

In my post of 10th August 2008 I wrote at length about the colonisation of Denis by Blue pigeons over the last 10-15 years and how today the island hosts a quite large and healthy population. There are no earlier records of blue pigeons on the island from visits in the early and mid-20th century or the 1970s so it would appear that man-induced changes have created suitable habitat on the island to enable it to establish a population on Denis.

In particular human activity has introduced various broadleaved tree species such that today some 30% of the island has a broadleaf canopy – and ongoing vegetation management programmes means this is likely expand considerably in the coming years.
Of particular note however are the fig (Ficus nautarum) and banyan trees (Ficus benghalensis) which now prosper on the island. The blue pigeon particularly likes to feast on the fruit of these trees. The small bright red fruit draws the birds in flocks to even very young trees – with at least 23 birds being counted in just one fig tree in 2008.

I have also frequently observed birds feeding on the white berries of the coastal bush “Veloutye” (Scaevola sericea) in the hotel grounds and around the southern point. During my visit last month I was able to capture a good photo of this behaviour (see sidebar). During the heat of the day it also common to see them in small groups perched in Bwa Kassan (Guettarda speciosa). The impression I receive of this behaviour is that the heavy shade offered by this coastal tree is ideal for the birds to shelter when the sun is high in the sky without them having to stray too far from a berried Veloutye bush.

Evidence of regular breeding continues with juveniles frequently being seen around the island – including one instance of twins I encountered a few months ago. The Blue pigeon is a remarkably beautiful bird with its red wattle and eye, powder grey neck and slate blue wings and lower body. The juvenile is very different however with no red colouration and drab grey and slate plumage with a tinge of an almost moldy green to the wings. One juvenile very kindly perched conveniently for me to photo in April (see sidebar).

Nature Notes 3

A belated summary of various observations following my visit to the island 16-18th April:

Blue-cheeked bee eaters (Merops persicus): I was very interested to find bee-eaters still present on the island we have had some birds stay on the island since the mass “invasion” in November when some 500 turned up for a period of days. Numbers rapidly declined after that, but there have always been some on the island since then. Interestingly during this last visit numbers definitely appeared up compared to March with several birds at a time to be seen hawking over the runway and from bushes along the east coast. A few days later I received an e-mail from Adrian Skerrett of the Seychelles Bird Records Committee (SBRC) asking whether Denis had received a new influx of bee-eaters as other islands had reported new sightings. It appears that birds heading north again to summer breeding grounds have passed back through the Seychelles archipelago. The mass influx of November and this return has apparently been seen throughout the archipelago and Adrian is working on a paper that summarises this migration pattern over the last 6 months. It is difficult on an island the size of Denis to estimate the number of bee-eaters that are present at any one time but I would have guessed there were approximately 20-25 on the island during mid-April representing an increase of 10-15 from March.

Whimbrels (Numenius phaeopus): A very distinct decline in Whimbrel numbers was evident. In November I counted a single flock of some 115 birds just on the reef flats off the North east coast and they have been abundant throughout the northern winter. A few birds stay all year on the island – presumably sub-adults – but it is clear that the bulk have started to return north again with only a few to be seen in small groups around the island in April.

Greater crested terns (Thalasseus bergii): a common sight in the morning at Pte Mme Guichard and later in the day on the sandstone outcrops just of the islands southern point – there currently appear to be nine birds on the island.

Grey Heron (Ardea cinera): The grey heron I first recorded in February is still resident spending quite a bit of its time now on the northern beach of the island hidden in amongst the fallen trees that project out across the beach and into the sea there.

Green turtle (Chelonia mydas). During my usual rounds I encountered my first green turtle track of the year – Green turtles can nest all year round but they show a distinct peak in nesting activity in the May-July period.

The island’s cattle have been kept north in the farm area at the estate for several months – being fed primarily on coconut shoots. This has allowed the vegetation at Belle Etoile to recover significantly in particular the Indian Mulberry trees (Morinda citrifolia), which the cattle particularly like to browse, have re-sprouted dramatically giving the pasture a more of a shrubland look. I also noted a lot of cotton plants in seed. Cotton (Gossypium hirsutum) was grown on Denis in the 1830s – 1850s and was a major cash crop for Seychelles at the time. Despite it being over 150 years since its cultivation it can still be seen in scrubland areas on the island. It has also been quite a weed in our sooty tern project area where removal of the coconut trees last year created the space and disturbed ground it needs to prosper.

The Green Islands Foundation (GIF) is committed to the mainstreaming of sustainable development. In the context of Seychelles, our chosen focus is on the key economic activities of Tourism, Fisheries and production landscapes. GIF has a sustainable development programme ongoing on the island of Denis (see http://denisisland.blogspot.com/ for more information) and is also keen to promote and facilitate similar initiatives on other islands. GIF has been working with three islands on the development of a common approach to maintaining their island’s rodent free and has just had an article published in the national press highlighting the importance of these islands and their rat-free status to national environmental initiatives.

Simply click on the image below to enlarge and read the article from today’s (25th May) Nation Newspaper.