A view from above : changing seas, seabirds and food sources

In this review we summarize what is known about mechanisms by which climate change may be affecting the populations of seabirds around the UK. Breeding success and adult survival are the key factors affecting changes in seabird populations, and food intake is implicated as a major determinant of both. The diet of most UK seabird species is almost exclusively sandeels, small clupeoid fish or zooplankton and it is clear that the marine pelagic food web is the key ecological system determining food supply. Hence, we develop the review by first considering how climate changes may affect primary production, and then examine how this propagates through the food web to zooplankton and fish culminating in fluctuations in seabird numbers. A trend of increasing numbers of many seabird species since 1970, particularly puffins, guillemots and razorbills, appears to have been reversed since 2000. The proximate cause of the recent declines seems to be a succession of 5 years of low breeding success for a range of species due to a shortage of food, especially sandeels. However, the connection with climate change remains uncertain, though there are indications that declines in the productivity of sandeel populations may be linked in some complex way to warming sea temperatures. The main conclusion is that no part of the marine food web, including fisheries, can be considered in isolation when trying to understand and predict the consequences of climate change for seabirds. Impacts can be expected in all parts of the system, and all parts of the system are interconnected

The use of webcams to monitor the prolonged autumn attendance of guillemots on the Isle of May in 2015

Although Guillemots at the southern edge of the range are known to return to the colonies in autumn, usually only opportunistic observations of this behaviour are available. In the autumn of 2015 we took advantage of the live interactive cameras on the Isle of May, Fife to make systematic checks of Guillemot colony attendance. Birds were recorded at dawn on 59 consecutive mornings between 23 October and 20 December after which webcam images ceased due to lack of power on the island. This prolonged period of attendance covered several periods of stormy weather and appears unprecedented at this colony. Presumably local feeding conditions must have been extremely favourable to enable the birds to spend so much time ashore

Gannet surveys in north-west Scotland in 2013

A photographic survey of the Gannet colonies off the north-west coast of Scotland in 2013 found 60,290 Apparently Occupied Sites (AOS) on St Kilda, 11,230 AOS on Sula Sgeir, 5,280 AOS on the Flannan Islands, 4,550 AOS on Sule Stack and 1,870 AOS on Sule Skerry. Since 2004, numbers had increased rapidly at Sule Skerry and the Flannan Islands (47.4% per annum (pa) and 7.5% pa respectively), but had changed little at Sule Stack and St Kilda. The harvested colony on Sula Sgeir increased by 2.2% pa, reversing the trend over the previous 10 years during which the population declined at 1.2% pa

The status of the gannet in Scotland in 2013-14

All 16 Gannet colonies in Scotland were counted in 2013–14. Combined colony totals indicated that Scotland currently holds 243,505 apparently occupied sites (58% and 46% of the east Atlantic and world populations, respectively). Numbers were divided very unevenly between the colonies with Bass Rock (now the world’s largest colony), St Kilda and Ailsa Craig together holding 70% of the Scottish population. Gannets started to nest on Barra Head, Berneray in 2007 and breeding may now be regular on Rockall. Numbers at St Kilda, Sule Stack and Scar Rocks were stable, but all other colonies had increased, some spectacularly. Overall the Scottish population increased by 33% between 2003–04 and 2013–14 at an average rate of increase of 2.9% per annum. Although the Gannet appears less vulnerable to climate change than many other UK seabirds, the proposed construction of major offshore wind farms close to colonies in the North Sea and the imminent ban on fishery discards, could pose future threats to this species

Small Partial Latin Squares that Cannot be Embedded in a Cayley Table

We answer a question posed by Dénes and Keedwell that is equivalent to the following. For each order n what is the smallest size of a partial latin square that cannot be embedded into the Cayley table of any group of order n? We also solve some variants of this question and in each case classify the smallest examples that cannot be embedded. We close with a question about embedding of diagonal partial latin squares in Cayley tables

Estimating true age-dependence in survival when only adults can be observed: an example with Black-legged Kittiwakes

In long-lived birds, pre-breeders are often difficult or impossible to observe, and even though a proportion of marked adults may be of known age, the estimation of age-specific survival is complicated by the absence of observations during the first years of life. New developments in MARK now allow use of an updated individual covariate. We used this powerful approach to model age-dependence in survival of Black-legged Kittiwakes (Rissa tridactyla) at a North Sea colony. Although only 69 marked breeders were of known age, there was strong evidence for a quadratic relationship between true age and survival. We believe that this simple but powerful approach could be implemented for many species and could provide improved estimates of how survival changes with age, a central theme in life history theory

Cómo estimar el efecto real de la edad verdadera en la supervivencia cuando sólo es posible observar individuos adultos: ejemplo de la gaviota tridáctila

In long–lived birds, pre–breeders are often difficult or impossible to observe, and even though a proportion of marked adults may be of known age, the estimation of age–specific survival is complicated by the absence of observations during the first years of life. New developments in MARK now allow use of an updated individual covariate. We used this powerful approach to model age–dependence in survival of Black–legged Kittiwakes (Rissa tridactyla) at a North Sea colony. Although only 69 marked breeders were of known age, there was strong evidence for a quadratic relationship between true age and survival. We believe that this simple but powerful approach could be implemented for many species and could provide improved estimates of how survival changes with age, a central theme in life history theory.En las aves de larga vida, a menudo resulta difícil o incluso imposible observar individuos prerreproductores, y si bien un porcentaje de adultos marcados pueden ser de edad conocida, la estimación de la supervivencia a una edad específica se convierte en una tarea compleja, puesto que no se dispone de observaciones de los primeros años de vida. Las nuevas características del programa MARK nos permiten utilizar una covarianza individual actualizada. Empleamos este impactante enfoque para modelizar el efecto de la edad en la supervivencia de la gaviota tridáctila (Rissa tridactyla) en una colonia del mar del Norte. Aunque sólo 69 aves reproductoras marcadas eran de edad conocida, contábamos con numerosas pruebas que apuntaban a una relación cuadrática entre la edad real y la supervivencia. Creemos que este simple pero eficaz enfoque podría aplicarse en muchas especies, proporcionando estimaciones mejoradas acerca de cómo la supervivencia varía con la edad, un tema central de la teoría de las historias vitales

The relative importance of physiological and behavioral adaptation in diving endotherms: a case study with great cormorants

Extensive morphological and physiological adjustments are assumed to underpin the adaptations of diving birds to high thermoregulatory costs. However, the role of behavioural adaptations has received little consideration. We have assessed the relative importance of physiological and behavioural adjustments in aquatic endotherms by studying the case of the poorly insulated great cormorant (Phalacrocorax carbo) in two contrasting thermal environments: Normandy (water temperature 12°C) and Greenland (water temperature 5°C). Major differences were found in the feeding behaviour of birds breeding in the two regions. Greenland birds showed a 70% reduction in time spent swimming relative to those in Normandy. Reduction in Greenland was achieved first by reducing time spent on the surface between dives and secondly by returning to land in between intensive bouts of diving. Total daily energy intake of cormorants was similar in both areas but prey capture rates in Greenland were 150% higher than those in Normandy. Our study shows that in a cold foraging environment, poorly insulated great cormorants significantly increase their foraging efficiency. To do this they rely on ecological adaptive patterns (minimization of time spent swimming in cold water and increased prey capture rates) far more than physiological adaptations (minimizing instantaneous costs). This finding supports predictions by Grémillet and Wilson (1999) that great cormorants can cope with a wide range of abiotic parameters despite their morphological handicaps, provided they can adjust their distribution to exploit dense prey patches