Saturday, 24 July 2010

Hatchlings!

The first stormie chicks have started hatching! Two hatched chicks were confirmed today in study nest sites. The incubation period of these two birds was around the expected 39-42 days and there had not been any evidence of egg neglect. The chick will be brooded by an adult for the first 10 days until it is capable of regulating its own body temperature without the warmth and protection of a parent. There are several more sites where hatching is expected in the next few days. Celebrations are under way with pineapple and mint mojitos!

Tuesday, 20 July 2010

Alamootie update

Out of about 140 study sites, eggs have been laid in 56 storm-petrel nests. While high levels of daytime occupancy of nests earlier in the season suggested that foraging conditions might be good, we have witnessed a fair amount of egg neglect in the last 2 weeks. Petrel eggs are specially adapted to survive chilling and interrupted incubation is common. However, previous research in the early 1990s revealed egg neglect in approximately 4% of nests, whereas current frequency of egg neglect is over 10%. We have also found a fair few dead eggs seemingly kicked out of nest sites. This suggests birds are neglecting their eggs (i.e. leaving them alone) and, in the meantime, another bird is coming in to prospect for a potential nest site and kicking out an egg. This may in fact mean that foraging conditions are not so good as we might have hoped.

A neglected egg which when removed and inspected was seen to have a couple of small dinks in the shell (slightly right of middle), making it unviable (Hannah Watson)




Out of about 45 nest-boxes on the island that we are monitoring, so far 7 boxes are occupied by incubating birds. The nest-boxes provide a great means of studying stormies, allowing visual inspection of nests with minimal disturbance. Here’s a sneaky peak of a stormie incubating an egg inside a nest-box...

Incubating stormie in a nest-box (Hannah Watson)

Seabird update - July 2010

Sadly, it does not seem like a particularly great year for seabirds in Shetland. Arctic terns appear to have failed across Shetland; the few pairs that I reported as having settled (rather late) onto eggs on Mousa in June, have all failed. Consequently, Arctic Skuas - whose productivity is closely tied in with that of Arctic Terns (the skuas primarily forage by stealing fish from terns!) - do not seem to be doing so well. Only three Arctic Skua chicks have been recorded so far this year, from three pairs. I discovered just a few days ago, that the “mixed” pair (comprising a light morph and a dark morph) that breed close to the Iron Age broch have a large chick. While ambling along the boardwalk, distracted by the calls of stormies from the boulder beach alongside me, I was suddenly aware of a pale morph Arctic Skua virtually on my head. I looked up to see a large, mostly-feathered chick ambling (in much the same manner as myself) on the boardwalk just a short distance from me.

Arctic skua chick - most of the feathers have grown in,
but it still retains some down around the neck and head (Hannah Watson)


After taking some poor photographs (see below - not helped by the howling wind and rain) and sheltering in the broch for 10 minutes from the deluge, I returned to my task of checking storm-petrel nest-boxes on the beach (see Alamootie update), watched closely by the adult Skua who proceeded to stand just 2 metres from me, giving me the evil eye.


A protective parent Arctic Skua watching my every move while I check stormie nest-boxes
(Hannah Watson)

Fulmar chicks started hatching just over a week ago. They seem to be very synchronous this year, with a sudden burst of hatching across the island. Adults brood their chick for about the first 10 days; after this time, the chick has got a little bigger (so hopefully is less likely to be snaffled up by a predator) and is able to regulate its body temperature without the warmth and comfort of a parent to snuggle up to. Most chicks are still being accompanied by an adult, but within the next few days, more and more will be left alone at the nest, allowing both parents to forage and provision the chick at a much higher rate, allowing it to grow rapidly. Despite this however, like all other petrels, the development period of fulmars is very long and the chicks will not fledge until they reach about 57 days old!


Cute fluffy Fulmar chick...until it starts to vomit all over you! (Rob Fray)

Thursday, 15 July 2010

Frustrating finds

Studying storm-petrels, one spends much of their life like this...



Or this...

Or this...



There doesn't seem much chance of spotting anything of interest, when you spend your life with your head buried in a wall. The orcas are probably leaping out of the water, dancing around in their full glory, while we remain completely oblivious.

Nights are spent, often frustratingly, searching for nests. Breeding sites are most easily found by listening for singing birds at nights. First you locate the approximate area of the sound, then quietly you get down on your hands and knees and press you ear up to the many cracks and crevices between stones or boulders, one by one, until you can locate the exact point of the call. Then, turning the torch on, you shine it into every gap available and hope that the beam of light eventually falls upon a bird. The response of birds to the torch-light is to either shut up instantly or start alarming at you. I’ve learned that I can communicate with them by mimicking their alarm call, precipitating repeated calls from them. The continued calling facilitates finding the bird, though on most occasions, you have to give up, knowing that the bird is buried deep down in the wall or beach, far out of sight. Maybe about 1 in 8 nests are visible and, even then, quite how much of the nest site or bird you can see is another matter. And, on top of this, we are limited to a narrow window of maybe 2 or 3 hours of darkness (highly variable depending on cloud cover) during which stormies are active and singing vigorously. Ideally, we are trying to find as many accessible nests as possible, such that, later in the season, chicks can be removed from the nest site enabling us to record biometrics and monitor growth rate of chicks in relation to visitor pressure, egg neglect and provisioning rate.

Nests are then re-located during the day to further investigate visibility and accessibility and to check for daytime occupancy. This can be further complicated by things such as cheeky gull chicks obstructing entrances to nest sites!

A cheeky great black-backed gull chick hiding in the entrance to a storm-petrel study nest!
(Hannah Watson)

Where possible, temperature loggers are deployed in nests to remotely monitor adult attendance and egg neglect during incubation. This often involves tearing your hands and arms to shreds as you try to squeeze your arm as far into a crack in a wall and have to use the sense of touch alone to excavate a suitable spot to embed a temperature logger. Then you pray that the bird will lay its egg on the temperature logger. Temperature loggers have been embedded into an artificial nest cup, moulded out of clay, with the hope of making a perfect depression to entice the bird to lay its egg in. We have had some success so far and certainly some birds and eggs have been seen sitting happily on loggers. We just need to convince a few more that our clay modelling skills produce a desirable home for their egg!

A neglected egg sitting on an artificial clay nest cup with a temperature logger embedded in it
(Hannah Watson - taken on my phone, hence not very good!)

Wednesday, 14 July 2010

Latest sightings

14th July: Grey Heron on Mid Loch, then flew off north. 2 rock doves.
12th & 13th July: Several Red Admirals seen.
12th July: The pair of Red-throated Divers on Mid Loch have successfully hatched a chick.
11th July: Swallow flying around bothy. First Fulmar chicks seen, which are probably now almost a week old.

Pair of ravens still regularly being seen over the last week or so.

Thursday, 8 July 2010

Alamootie update

There has been a rush of laying this week and, as of Tuesday, 34 birds from around 130 study nest sites have been confirmed as incubating an egg! Daytime occupancy of nest sites has been over 25%, suggesting that lots more birds may be about to lay.
Typical nesting area on Mousa's South Isle, where extensive quarrying of stone took place in the past
(Hannah Watson)
Stormies breed all over the island of Mousa using cracks and crevices in the boulder beach, the many dry stone walls that criss-cross the island (remaining from the days in which crofters farmed the land), heaps of stone slabs (remnants of extensive quarrying) and in the Iron Age broch.

Inside Mousa's Iron Age broch (Hannah Watson)

Nests are checked every 5 days for the presence of a bird and evidence of having laid. Due to the nature of nest locations, visibility is often difficult and it is not always possible to determine if a bird is sitting on an egg or not. In this case, nests are visited and checked on up to 3 consecutive days. If a bird is present for 3 days in a row, it can be confidently assumed the bird is incubating an egg.

Study nest sites are located all over the island in areas subjected to varying levels of visitor pressure. Visitor movements are being recorded using beam counters and cameras. The beam counters have a sensor emitting an infra-red beam; each time a person walks by, the beam is broken and a count is made. Camera traps are being used alongside the counters to validate the data recorded by beam counters and check that sheep are not being counted too!

Camera and beam counter hidden within one of the dry stone walls
(Hannah Watson)


Wednesday, 7 July 2010

Otter encounters

At last, we can publish photographic evidence of the stunning otter that we watched fishing two weeks ago in the West Ham...

Otter gorging on the tail stock of a sizeable fish in the West Ham
(Mark Bolton)

This Great Northern Diver, not quite in full breeding plumage, was seen in the West Ham a few times in late June....


 Great Northern Diver, West Ham
(Mark Bolton)

Saturday, 3 July 2010

Latest sightings

Friday 2nd July
Fantastic views of an otter again. One was spotted on the shore of the West Ham, just as it was entering the water. After playing in the water for just a wee while, it vanished. A few minutes later, it reappeared bounding back up the beach and then it lolloped across the grassy plain lying between the West and East Hams, then turned north and headed up the hill behind the bothy.

Pair of ravens were lingering around the island today, seen in the West Ham in the morning, and then later, chilling out at the top of the broch.

Thursday 1st July
Great Northern Diver in full breeding plumage in the West Ham.