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.