August, 2016

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Scottish Nature Notes

Keep up to date with the latest wildlife and nature news in Scotland. Regular blogs from RSPB Scotland's conservation teams across the country. Writing about Scotland's amazing wildlife & natural environment.
  • Surveying kittiwakes: how times have changed at Sumburgh Head

    Paul Walton is RSPB Scotland’s Head of Habitats and Species. He recently made a visit to the kittiwake colony at Sumburgh Head, Shetland, that he surveyed in the 1990s. In this blog he writes about this visit and what he discovered about the colony on his return trip. If you love seabirds as much as we do we could use your support right now. RSPB Scotland is currently asking supporters to sign a marine e-action calling for better protection of Scotland's seabirds. It is part of a public consultation on 10 potential new protected areas. If you would like to add your name and show your support for our seabirds you can do so by clicking here.

    On a bleached cliff-top, sea-pinks tremble in the gusts and breezes. Fulmars cut the air with stiff wings, juddering and swaying against updrafts. Below them, kittiwakes wheel and holler, guillemots whirr in at speed, trafficking prey fish to the offspring, careering in to the breeding ledges, greeting and quarrelling, chicks begging and gulping and digesting. Gulls and skuas are patrolling, seeking the next predatory opportunity, and beneath it all a deep green Atlantic swell batters and caresses the rock face. This is pungent fertility, grace and menace on an oceanic stage.

    I only have to sit here at this basement desk and imagine a seabird colony in June, and my pulse quickens. For most of the 1990s I worked for Glasgow University as a seabird researcher, based at Sumburgh Head at the southern tip of Shetland. Between April and September every day was spent on and around the cliffs, monitoring chick growth, ringing and radio-tracking adult seabirds, assessing breeding performance.

    But for me, even more than the excitement of hands-on science, the most memorable activity was the hide watches. The research team would take turns to sit in small huts dug-in to the cliff-tops, weighed down with boulders. From these hidden viewpoints we watched and recorded the daily life of the colony. These watch rotas would go on for days at a time, and called for absolute concentration so that we gathered accurate data on presence and absence of breeding adults at the colony, the feeding frequency of the chicks, the timing of egg laying and chick hatching.

    There is something spellbinding about spending long periods sitting quietly, unseen, and simply looking, witnessing wildlife first hand. It is less a theatrical drama unfolding, or voyeurism, more a close and intimate engagement with the reality of nature, and that is an immense privilege. 

    In some years there were low numbers of sandeels, the keystone prey fish species in Scotland’s marine ecosystem. Then, we would watch our study colony of 60 or so kittiwake nests reach extremes whereby an adult would depart on a foraging trip, heading out from the colony straight into the teeth of a North Sea gale, and not returning sometimes for fully 48 hours. Parent kittiwakes share the nest duties 50:50 and, during this time, that bird’s mate must remain at the nest constantly, unable to feed, guarding eggs and chicks from predators. But a small bird - and kittiwakes are astoundingly delicate in the hand - with a high metabolic rate will struggle with such long periods of forced starvation.

    Seabirds are long-lived animals and most will breed several times during their lives. Some of these breeding attempts will fail quite naturally. These kittiwakes had, in effect, to make a decision: either stay on, enduring periods of starvation that, together with flying huge distances to find enough food for the young, might lead to long term physiological damage for the adult; or abandon this year’s breeding attempt and try again in future.

    In the very poorest year for sandeels during our 1990s study, we watched as each kittiwake pair slowly, one after the next, abandoned their nest. The moment a chick was left alone, a gull or a skua, with hungry chicks themselves of course, would swoop in and take it. That year breeding success in the kittiwake colony was zero. But we returned to our hide the following spring to see the cliff occupied once more, with the same parent birds (the very same individuals that we had ringed, each with a unique colour combination) returning to breed successfully. We toasted them with cans of lager, and set about recording the year’s successes in our notebooks.

    As the years of fieldwork proceeded, the unfolding life stories of these birds took on a sense of timelessness. The marine environment fluctuated, with big differences between the years, but I began to sense how seabird adaptations – not least their longevity and multiple breeding attempts in each adult lifespan – helped these incredible birds persist in, and as an integral part of, that marine ecosystem.

    The Glasgow University research team’s colony photograph of the Sumburgh kittiwakes, 1993: each nest is marked with a red dot. Virtually all of these nests are now abandoned. c/o Prof Pat Monaghan.

    It turns out I was complacent. I recently returned to Sumburgh Head at the height of the seabird breeding season. I was staggered, by what I saw. That sense of timelessness and continuity crumbled in seconds. The cliff-top kittiwake study hide that we had built back in 1990 was, to my amazement, still there – lichen encrusted and weathered, but still standing. The kittiwake colony that it looked onto, on the cliff opposite – the colony we had followed so closely and intimately for so many years - was silent. Of the 60 busy, screaming, displaying, fighting pairs, three remained, deep in the cliff cave – with no chicks visible. I could hardly believe my eyes. I left Sumburgh wounded.

    This tragedy has played out across Shetland and Orkney, in other parts of the UK, beyond in the Nordic countries, and indeed across the world. Kittiwakes, arctic terns, arctic skuas, puffins – birds for which Scotland has global significance - have experienced poor food supply for such long extended runs of years that the longevity of individual adults is insufficient to maintain numbers, and huge population declines have now taken hold.

    The cause is deep and fundamental shifts in the marine food-chain driven by human-induced climate change. Recent decades have seen the biomass of the zooplankton, on which the sandeels feed and depend, plummet by more than 70% in the NE Atlantic. Climate change is warming the sea surface and this is generating asynchrony in the timing of zooplankton breeding, and the timing of the annual phytoplankton bloom on which they graze. The system is out of seasonal synchrony and, to compound this, nutrient-poor warm water plankton species are beginning to replace the nutritious cold water species. Fewer sandeels is the result, with inevitable knock-on effects on the breeding success and survival of their predators - the seabirds.

    The human impact on nature has, in our lifetimes, moved to a new and terrifying scale - and these climate change effects in the marine environment are for me the starkest illustration yet of how profound that impact has become.

    But we can act to help. RSPB Scotland and our conservation partners lobbied hard and successfully for a Scottish Marine Act. We are pressing for the effective management of a network of protected areas at sea, where seabirds and other marine predators can feed. We are also working to build a programme that will restore as many seabird breeding islands as possible - making them free from the mammal predators, introduced by people, that decimate breeding seabirds.  

    If you would like to do something positive today to help protect Scotland's seabirds then we would urge you to sign our marine e-action. The Scottish Government has put forward 10 marine sites to be officially designated as protected areas for the seabirds that use them. A public consultation is open now, to get your views about whether they need to be protected. We have responded asking that they are all designated as soon as possible and you can support our call to action here. It's a great first step towards getting these birds the protection they need.

  • Wonderful wildlife at Aberfoyle

    The Lodge Forest Visitor Centre in Aberfoyle is a five-star visitor attraction run by Forest Enterprise Scotland. It has a wildlife room - which is a joint project between Forest Enterprise Scotland and RSPB Scotland - where visitors can watch fantastic wildlife nearly every day, with webcams showing live nests and highlight reels. It’s been a brilliantly busy summer this year - wildlife officer Jenni Fulton brings us this summary.

    During 2016, a pair of ospreys provided no end of drama in Aberfoyle. The male and female were both completely new to the site, having not settled here before. Neither of the birds had been ringed so unfortunately we didn’t know anything about their history, for example their age or where they came from. The pair quickly learned to build and defend a nest, bond with each other and produce three blotchy brown eggs.

    When the first was laid, the male was curious about this new object in his nest, but the female was initially reluctant to let him observe or sit on the eggs, until he literally shouldered her aside. He spent ten minutes repeatedly sitting down and standing up, before seemingly getting bored and flying off! Luckily mum was on hand to take over again.

    Despite weeks of snow, heavy rain, gales and unseasonably cold temperatures, the birds’ patient egg incubation paid off and they were rewarded with three healthy young chicks - two males and one female. At six weeks old, all three chicks were ringed and both males also had satellite trackers fitted so they can be monitored as they make their first migration to North or West Africa, where they will spend the next few years of their lives.

    The osprey chicks fledged in August at around eight weeks of age, although the first flights were heart-stopping as first one, then another failed to make safe landings - clinging on to the edge of the nest before struggling to get back on board. Ospreys can perish if they miss the nest as they may not be able to take off again from a busy forest floor, and they are still dependant on fish being brought in to them by their parents.

    Sadly, many ospreys don’t make it to adulthood and often we don’t understand why. But with trackers fitted, the data gathered will allow us to see exactly where these young birds go and whether they survive, which will contribute to the valuable knowledge needed to offer protection for this amazing species in future.

    This year at Aberfoyle, we were also privileged to be able to watch a pair of peregrine falcons nesting on a nearby cliff edge. They found a south facing ledge with a slight overhang above, where they were warmed by the morning sun and protected from rain or snow. Four nut-brown eggs hatched after five weeks, producing four perfectly white chicks, which quickly became four boisterous young male birds.

    Day after day they grew, until they were no longer fluffy bundles - but slightly smaller versions of their parents, with handsome barring on their chests and distinct black eye masks. With the ledge available to clamber about on, the chicks gradually wandered out of sight more and more often, although at meal times they were quick to reappear for a frantic feeding frenzy. Now in August, they can still be seen and heard flying around nearby.

    Unfortunately owls have had a pretty tough season at Aberfoyle, with many of the nest boxes that have been installed to give these animals a home going unused. However, this has been to the benefit of other species such as gooseanders, which have been taking advantage of the spare space and moving in – some managing to lay 12 or more eggs at a time!

    As the forest is home to pine martens, the owl boxes need to be positioned so these predators can’t climb down from adjacent trees and get inside. The tree trunks also have to be covered with material they cannot scale. One box we had a camera on was inhabited by barn owls and we knew at least two eggs had been laid. We eventually saw two white fluffy bundles, but then eventually only one chick reaching fledging age.

    From the hide, viewing areas and on the wildlife cameras at the site, visitors can also see red squirrels, great spotted woodpeckers, jays, and nuthatches, as well as great, blue and coal tits. Recently a sparrowhawk has taken to catching unwary prey down by the feeders too.

    The ospreys may have fledged and left the site now, but you can still view live wildlife footage of plenty of other species, and special films of this year’s families, at the Lodge Forest Visitor Centre. There’s also a special bat event taking place on Saturday 27 August 27. For more information, click here.

  • Toad tales

    Charlie McMurray is an intern at RSPB Scotland working on 'all nature' projects: mammals, amphibians and insects. This is her latest update on natterjack toads.

    By the beginning of May, the noisy natterjack toads at Mersehead were out in full force for the first time this year. Their loud chorus was the cue we needed to begin the final round of our three-year surveys to estimate the population size. Three surveys were performed at night each year, in which every toad we found was captured, photographed and identified by the wart pattern on its back.

    Each of these patterns is as unique as a snowflake, so we can recognise individuals without marking them. The proportion of recaptured toads to those caught only once is suggestive of how big the population is. For example, if the majority of individuals weren’t found again, the population is probably relatively large, and vice versa.

    To find the recaptures from the photos, we’ve been testing an identification programme called Interactive Individual Identification Software (I3S), as in ‘Nattering with Natterjacks’. The results from the previous two years’ photos were disappointing because the toads were flaunting such a wide range of poses, skewing their wart patterns. I3S, therefore, couldn’t compare the patterns easily.

    In the past, the toads were photographed against a laminated sheet, but this year we worked on limiting their movements. All sorts of cunning devices were considered, from restraining them inside petri dishes to creating plunger cages, where the toad would be pushed upwards and gently held against netting. But, with their breeding season looming ever closer, we remained unconvinced.

    Our most exemplary toad, Dave, demonstrating the toad-sponge technique. Dave has given himself up twice every year, so we know he’s been roaming the merse for at least six.

    Just as the toads started to emerge from their winter hideouts, an idea sprang to mind: the toads could simply sit inside hollows cut out of basic sponges. The toads seemed to approve, sitting calmly, possibly somewhat perplexed. As burrowers, perhaps they felt safer within a hollow or maybe the rougher material wasn’t as foreign to them as the slippery sheet.

    After the fun bit, it was back indoors to plug the photos into I3S. First, some good news: when the software found the correct match, it was always ranked first out of fifty possibilities. Previously, the match could’ve been anywhere in that long list, so the upgrade was much more time-efficient. The not-quite-so-good news is that the software found eleven out of fourteen matches, which means there’s still some fine-tuning to do. It’s a big improvement on the results from the last two years though.

    Now, the population size estimates – the moment we’ve all been waiting for! In 2014, the year of the storm that prompted these surveys, there were estimated to be 30 breeding males. In the second year, the number rose steeply to 156. The figure increased once again to a staggering 248 males this year. We’ve focussed on the males because their breeding behaviour is much more repetitive than the females’, who only come to the breeding pools once, maybe twice, a season. That means we’re highly unlikely to recapture them.

    This juvenile male, only 2.2cm long, worked his way into a survey. He was surrounded by calling adult males in a breeding pool, so he’s a little too big for his boots.

    Reflecting on the population predictions, we’ve speculated that there were so few breeding individuals in 2014 because the conditions were too bad for spawn to survive. It’d have been a huge loss of energy for the adults with a great deal of risk. We’re cautious about 2016’s figure, believing that it overshot the mark. The weather for the second survey of the year wasn’t ideal, so not many toads were captured, meaning that there was less chance of finding recaptures. Remember, the fewer the recaptures, the bigger the population is suggested to be.

    If we take 2015 to be the most reliable estimate for a normal year, the entire adult population (including females) could be anywhere between 265 and 374 individuals. Considering we only predicted it to consist of about 30 before the surveys started, this is extremely positive news. It’s also demonstrated how hardy these charismatic little amphibians can be.

    The chorus has quietened down now, so here ends our intensive natterjack surveys. The work isn’t over yet, though. It’s still a constant effort to keep the toads’ habitat to their liking. A few were found in new places on the reserve this year, so the question is, is their population expanding or are they beginning to move away? There’s plenty to keep us occupied, so you haven’t heard the last of the natterjack toads.