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Synchrony in demographic rates between spatially disjunct populations is a widespread phenomenon, although the underlying mechanisms are often not known. This synchrony and its spatial patterns can have important consequences for the long-term persistence of metapopulations and can also be used to infer drivers of population dynamics. Here, we examined spatial patterns of synchrony in the breeding success of black-legged kittiwakes Rissa tridactyla in the UK, using an extensive dataset on kittiwake breeding success and 2 different ways of measuring synchrony: one reflecting synchrony in inter-annual fluctuations only (rdiff) and one reflecting synchrony in both inter-annual fluctuations and long-term trends (r). We found that between-colony synchrony in breeding success decreased with distance up to just over 200 km but that some colony pairs showed stronger or weaker synchrony than expected based on distance. This was also reflected in the configuration of spatially coherent clusters of kittiwake colonies with synchronous breeding success. Further, we compared the support for different drivers of these spatial patterns, including trophic interactions and weather conditions. We found that the spatial dynamics of the kittiwakes’ main prey in this region, the lesser sandeel Ammodytes marinus, appeared to play some role in generating synchrony in long-term patterns, but their role in generating synchrony in inter-annual fluctuations was less clear. The study shows that examining spatial patterns in synchrony can provide useful information for inferring potential drivers and the spatial scale over which they are acting.

The black-legged kittiwake Rissa tridactyla is a pelagic seabird whose population has recently declined in most parts of the North Atlantic and which is red-listed in most bordering countries. To investigate a possible cause for this decline, we analysed the population dynamics of 5 kittiwake colonies along the Norwegian coast, ranging from 62° to 71° N, over the last 20 to 35 yr. By quantifying the importance of sea surface temperatures (SST) in relevant areas of the North Atlantic, we tested the importance of climatic conditions throughout the populations’ annual cycles. We found no synchrony among colonies; however, SST affected population dynamics, explaining between 6% and 37% (average 18%) of the variation in annual population growth rate. While dynamics of the southerly colonies were mainly affected by winter conditions in the Grand Banks area, dynamics of the northernmost colonies were dominated by autumn conditions off Svalbard. Negative slopes indicated stronger population decline under warmer ocean conditions. Population dynamics were affected both via adult survival and offspring recruitment, as evidenced by the presence of unlagged effects as well as effects lagged by the age at recruitment. Finally, we performed population viability analyses taking into account the projected warming trends for the future. The median time to extinction of the Norwegian colonies was 52 to 181 yr without considering covariates; 45 to 94 yr when considering the effects of SST but ignoring future warming; and 10 to 48 yr when ocean warming, based on a ‘business as usual’ scenario, was taken into account. Global warming · Non-breeding distribution · Population dynamics · Population viability analysis · Rissa tridactyla · Sea surface temperature

To gain further insight into the foraging behaviour of predator species, it is essential that interactions between predators, their prey and the surrounding environment are better understood. The primary purpose of this study was to determine the underlying processes, both physical and biological, driving variation in the times and locations of seabird foraging events. Using fine-scale simultaneous measurements of seabird abundance, prey density and oceanographic variability collected during an at-sea survey in the Firth of Forth region of the North Sea, zero-inflated negative binomial models were applied to identify the underlying processes driving foraging behaviour in 2 seabird species: the common guillemot Uria aalge and the black-legged kittiwake Rissa tridactyla. Both guillemot and kittiwake models showed consistency in their results; specific tidal states and thermal stratification levels explained observed increases in abundance. The secondary purpose of this study was to identify key oceanographic processes driving variability in prey density and determine if these were comparable to those underlying the behaviour of foraging seabirds. Log-transformations of 2 measures of prey density, NASC-40-50(MAX) and NASC-50-70(MAX), were modelled using generalised least squares. Similar tidal conditions and thermal stratification levels explained distributional patterns, suggesting that these processes act to increase prey availability, creating profitable foraging opportunities for predators to exploit. This has been termed the tidal coupling hypothesis and identifies that critical marine habitats occur not only at limited spatial locations but also within specific temporal intervals relating to the tidal cycle. Further more, by incorporating this oceanographic influence on foraging habitat, fine-scale predator-prey relationships were also identified. Foraging guillemots and kittiwakes displayed a Type II functional response to increasing values of NASC-40-50(MAX).

I examined ~2700 food samples collected from adult and nestling black-legged kitti- wakes Rissa tridactyla from 1978 through 2011 on Middleton Island in the Gulf of Alaska. The kit- tiwake diet was composed chiefly of fish, but invertebrates were taken in appreciable quantities in April and May. Upon spring arrival at the colony, adult kittiwakes foraged regularly at night on vertically migrating mesopelagic prey — lanternfishes (Myctophidae), squids, crustaceans, and polychaetes — a behavior they largely discontinued by egg-laying. During incubation and chick- rearing, food samples contained mostly (~85% by weight) Pacific sand lance Ammodytes hexa- pterus, capelin Mallotus villosus, Pacific herring Clupea pallasii, sablefish Anopoploma fimbria, krill (Euphausiidae), and juvenile salmon Onchorynchus gorboscha and O. keta. A salient finding over the longitudinal study was the emergence, twice, of capelin as a dominant forage species — once in 2000 to 2003, and again in 2008 through 2011. Kittiwakes responded to capelin availability by producing markedly higher numbers of fledged young. The 2000 to 2003 event corresponded to a previously documented shift to cooler conditions in the NE Pacific, which apparently was rel- atively limited in magnitude or duration. The more recent transition appears stronger and may be more lasting. I submit that 2008 was an important turning point, marking a substantive reversal of warm conditions that began with the well-documented regime shift of 1977. That interpretation is consistent with the existence of a ~60 yr cycle in ocean and atmospheric conditions in the North Pacific. All else being equal, it predicts the next 20 to 30 yr will be favorable for species such as kittiwakes and Steller sea lions, which seemed to respond negatively to the 1977 to 2007 warm phase of the Pacific Decadal Oscillation.

We examined the reproductive ecology of black-legged kittiwakes Rissa tridactyla in several breeding colonies in the North Pacific to test if inter-annual changes in the Pacific Decadal Oscillation (PDO), Winter Ice Cover (ICI), or local sea-surface temperature (SST) predict changes in productivity (fledglings per nest) or nutritional stress (corticosterone). We explored the implica- tions of the observed variation in productivity and stress for projected population dynamics based on a previously demonstrated corticosterone−survival relationship. Although productivity was highly variable (0 to 0.9 fledglings nest −1 ), the relationships between productivity and environ- mental indices were weak, with local SST providing slightly more explanatory power than PDO or ICI, suggesting that local factors rather than large-scale climate variability may determine varia- tion in productivity. The relationships between stress and environmental indices were stronger than the relationship between productivity and environment. The measured response of stress to environment showed opposite signs between the southern and northern colonies, and typically implied annual mortality rates varying from 11 to 17%. The observed relationships between cli- mate and stress indicate that anticipated warming might bring at least short-term demographic benefits for kittiwakes in the Bering shelf region, while having negative impacts on birds breeding in the Gulf of Alaska and western Aleutians. We predict decline (without immigration) for colonies with the lowest productivity and conclude that climate variability is likely to affect survival of North Pacific kittiwakes on a region-specific basis. Longevity of these birds may not always be sufficient to buffer their populations from low reproductive performance.

Seabirds are thought to time breeding to match the seasonal peak of food availability with peak chick energetic demands, but warming ocean temperatures have altered the timing of spring events, creating the potential for mismatches. The resilience of seabird populations to climate change depends on their ability to anticipate changes in the timing and magnitude of peak food availability and 'fine-tune' efforts to match ('Anticipation Hypothesis'). The degree that inter-annual variation in seabird timing of breeding and reproductive performance represents anticipated food availability versus energetic constraints ('Constraint Hypothesis') is poorly understood. We examined the relative merits of the Constraint and Anticipation Hypotheses by testing 2 predictions of the Con- straint Hypothesis: (1) seabird timing of breeding is related to food availability prior to egg laying rather than the date of peak food availability, (2) initial reproductive output (e.g. laying success, clutch size) is related to pre-lay food availability rather than anticipated chick-rearing food availabil- ity. We analyzed breeding biology data of common murres Uria aalge and black-legged kittiwakes Rissa tridactyla and 2 proxies of the seasonal dynamics of their food availability (near-shore forage fish abundance and sea-surface temperature) at 2 colonies in Lower Cook Inlet, Alaska, USA, from 1996 to 1999. Our results support the Constraint Hypothesis: (1) for both species, egg laying was later in years with warmer sea-surface temperature and lower food availability prior to egg laying, but was not related to the date of peak food availability, (2) pre-egg laying food availability explained varia- tion in kittiwake laying success and clutch size. Murre reproductive success was best explained by food availability during chick rearing.

Each year, millions of seabirds migrate to the North Water Polynya, northern Baffin Bay, to feed in its productive waters during the 6 months that the polynya is free of ice. We evaluated seasonal shifts in diets of 3 species using the North Water: dovekie Alle alle, thick-billed murre Uria lomvia, and black-legged kittiwake Rissa tridactyla. Diets were assessed through a combination of stable isotope analysis of muscle tissue, fatty acid analysis of subcutaneous fat, and stomach content analysis. Dovekies had the lowest δ15N values and hence lowest trophic level in spring and summer, corresponding to their consumption of herbivorous copepods. In fall, their δ15N values increased as they switched to feeding at a higher trophic level on primary carnivores such as amphipods and fish. Throughout the study period, kittiwakes and murres had stomach contents and stable isotope values similar to dovekies in fall. Fatty acid signatures of black-legged kittiwakes and dovekies feeding in fall were similar, likely due to the reliance of both species on the pteropod Limacina limacina. Our study highlights the seasonal nature of prey availability and seabird diets in the polynya, as well as the utility of simultaneously using conventional stomach content analysis and stable isotope and fatty acid analyses to infer dietary patterns in marine food webs. © Inter-Research 2008.

In his seminal paper about using seabirds as indicators of marine food supplies, Cairns (1987, Biol Oceanogr 5:261-271) predicted that (1) parameters of seabird biology and behavior would vary in curvilinear fashion with changes in food supply, (2) the threshold of prey density over which birds responded would be different for each parameter, and (3) different seabird species would respond differently to variation in food availability depending on foraging behavior and ability to adjust time budgets. We tested these predictions using data collected at colonies of common murre Uria aalge and black-legged kittiwake Rissa tridactyla in Cook Inlet, Alaska. (1) Of 22 seabird responses fitted with linear and non-linear functions, 16 responses exhibited significant curvilinear shapes, and Akaike's information criterion (AIC) analysis indicated that curvilinear functions pro- vided the best-fitting model for 12 of those. (2) However, there were few differences among para- meters in their threshold to prey density, presumably because most responses ultimately depend upon a single threshold for prey acquisition at sea. (3) There were similarities and some differences in how species responded to variability in prey density. Both murres and kittiwakes minimized vari- ability (CV < 15%) in their own body condition and growth of chicks in the face of high annual vari- ability (CV = 69%) in local prey density. Whereas kittiwake breeding success (CV = 63%, r 2 = 0.89) reflected prey variability, murre breeding success did not (CV = 29%, r 2 < 0.00). It appears that mur- res were able to buffer breeding success by reallocating discretionary 'loafing' time to foraging effort in response (r 2 = 0.64) to declining prey density. Kittiwakes had little or no discretionary time, so fledging success was a more direct function of local prey density. Implications of these results for using 'seabirds as indicators' are discussed.

Food availability comprises a complex interaction of factors that integrates abundance, taxonomic composition, accessibility, and quality of the prey base. The relationship between food availability and reproductive performance can be assessed via the nutritional stress (NSH) and junk- food (JFH) hypotheses. With respect to reproductive success, NSH posits that a deficiency in any of the aforementioned metrics can have a deleterious effect on a population via poor reproductive suc- cess. JFH, a component of NSH, posits specifically that it is a decline in the quality of food (i.e. energy density and lipid content) that leads to poor reproductive success. We assessed each in relation to reproductive success in a piscivorous seabird, the black-legged kittiwake Rissa tridactyla. We mea- sured productivity, taxonomic composition, frequency, size, and quality of meals delivered to nestlings from 1996 to 1999 at 6 colonies in Alaska, USA, 3 each in Prince William Sound and Lower Cook Inlet. Productivity varied widely among colony-years. Pacific herring Clupea pallasi, sand lance Ammodytes hexapterus, and capelin Mallotus villosus comprised ca. 80% of the diet among colony- years, and each was characterized by relatively high energy density. Diet quality for kittiwakes in this region therefore remained uniformly high during this study. Meal delivery rate and meal size were quite variable among colony-years, however, and best explained the variability in productivity. Par- ent kittiwakes appeared to select prey that were energy dense and that maximized the biomass pro- visioned to broods. While these results fail to support JFH, they do provide substantial support for NSH.

The population dynamics of marine top predators such as seabirds may be self-regulating through local prey depletion, or they may reflect environmentally induced fluctuations in prey availability. Both mechanisms are not mutually exclusive. We examined spatio-temporal variation in breeding success of black-legged kittiwakes Rissa tridactyla, a seabird widely monitored in the British Isles. Kittiwakes here feed mostly on lesser sandeels Ammodytes marinus, a species that is strongly tied to specific sediment types and therefore shows a strong regional population structure. Neither kittiwake colony growth rate nor breeding success correlated negatively with colony size as expected under local prey depletion in the absence of regional variation in carrying capacity. We used multivariate analyses of breeding success data for 42 kittiwake colonies to identify clusters showing synchronised variation in success, and compared these with known sandeel aggregations identified from fish and fishery surveys. A number of geographically distinct clusters of kittiwakes were identified, and these were largely congruent with sandeel aggregations. Major sandeel aggregations with clear associated clusters of kittiwake colonies occurred off of east England and east Scotland, while western coasts of Britain were characterised by smaller aggregations and less obvious kittiwake clusters. There was considerable regional variability in sandeel recruitment, and this was reflected in mostly uncorrelated time series of kittiwake breeding success between different regions. These results indicate that regional variation in prey availability had a stronger effect on kittiwake dynamics than local prey depletion. An appreciation of the appropriate spatial scale of prey dynamics thus improves understanding of the dynamics of marine predator ‐ prey systems.

Lipid class and fatty acid compositions were determined in common eider (Somateria mollissima), black-legged kittiwake (Rissa tridactyla) and northern fulmar (Fulmarus glacialis) from Kongsfjorden, Spitsbergen. Muscle and liver were sampled in all species, while fat tissue was sampled in eiders and fulmars. Triacylglycerols (TAG) dominated the lipid class compositions of all tissues, and the major fatty acids found in TAG were: 18:1n9, 16:0, 18:0, 20:5n3 and 16:1n7 for eider; 16:0, 18:1n9, 18:0, 20:1n9 and 16:1n7 for kittiwake; 18:1n9, 16:0, 20:1n9, 22:1n11, and 18:0 for fulmar. To attain information on prey composition, fatty acid signature analysis was performed on muscle fatty acid profiles of the bird species, together with fatty acid data from potential prey species. This study of lipids combined with stable isotopes supports the following findings: (1) Common eiders are strongly linked to the benthic food chain, through both fatty acid compositions (high levels of 20:4n6) and stable isotope values (high levels of δ 13 C). (2) Black-legged kittiwakes and northern fulmars are linked to the pelagic food chain, through both fatty acid compositions (high levels of 20:1n9 and 22:1n11) and stable isotope values (low levels of δ 13 C). The high level of 20:1 and 22:1 moieties also indicates the importance of Calanus in the Arctic pelagic food chain supporting fulmar and kittiwake. (3) The levels δ 15 N show that of the 3 species, the fulmar occupies the highest trophic level, followed by kittiwake and common eider.

To better understand how fluctuations in prey abundance may impact seabird repro- ductive success, we studied short-term changes in prey populations and their effect on prey selection and brood-rearing in the black-legged kittiwake Rissa tridactyla, a predator of near-surface-school- ing forage fishes. Our fine-scale approach involved a weekly assessment of forage fish abundance and brood-rearing conditions during 4 consecutive years (1996 to 1999) at the Shoup Bay kittiwake colony in Prince William Sound, Alaska. We conducted forage fish surveys from a fixed-wing aircraft to determine weekly prey abundance throughout the known foraging range of breeding kittiwakes. Our results provide clear evidence that short-term fluctuations in prey availability are responsible for dramatic, within-season changes in the breeding conditions of black-legged kittiwakes. Adult kitti- wakes often showed immediate response to changes in the prey base by altering prey selection; how- ever, there were instances when kittiwakes selected prey species disproportionate to their availabil- ity (typically selecting for Pacific herring Clupea pallasi and against Pacific sand lance Ammodytes hexapterus). Changes in prey selection often resulted in striking differences in the amount of time required to obtain a load of food. The cascading effects of longer foraging trips was translated into reduced nestling growth and survival. Of the 3 components of energy provisioning to nestlings (meal delivery rate, meal size, and energy density), meal delivery rate had the strongest and most consis- tent positive effect on nestling growth and survival. Overall, these results demonstrate that complex foraging conditions limit the reproductive success of a central place-foraging species relying on an ephemeral food source. Moreover, we demonstrated that feeding conditions during the first 2 wk of brood-rearing were most critical for survival of the brood. Given the potential for such marked within-season variation in breeding conditions, it is critical that investigators adequately sample throughout the brood-rearing period, or, alternatively, select that portion that is germane to their study.

The lesser sandeel Ammodytes marinus is a key prey species for many avian predators in the North Sea, and is the target of the largest single species fishery in the area. This has led to con- cern about the potential impact of the fishery on seabirds. The most vulnerable predatory species are small and surface-feeding, characteristics that are exemplified by the black-legged kittiwake Rissa tridactyla. This paper reports on the first assessment of seasonal changes in prey composition and prey size for the kittiwake in the North Sea during 4 breeding seasons (1997 to 2000) in which breed- ing success varied dramatically. Kittiwake diet showed little inter-annual variation, with a well- defined seasonal change from planktonic crustacea in early spring, to 1+ group sandeels in April and May, to 0 group sandeels in June and July. However, there was evidence that temporal differences in sandeel life history events were well reflected in both kittiwake diet and breeding success. Thus, the most successful year (2000) was characterised by the earliest appearance of 0 group sandeels, while the least successful season had the latest appearance. There was also a link between annual varia- tions in breeding success and sandeel size such that success was lower when 0 group sandeels were smaller and hence of lower energy value. Our study included 3 seasons (1997, 1998, 1999) during which the industrial fishery was operating within 50 km of the study colony and 1 (2000) in which the fishing grounds were closed. The higher breeding success in 2000 than in the other years suggests that the closure of the fishery might have had an immediate and positive effect on kittiwake produc- tivity. However, as the dietary data indicated, the earlier appearance and rapid growth rates of 0g roup sandeels in 2000 suggests that the enhanced breeding success was more likely to have been a response to environmental factors influencing the growth and timing of life history transitions of this prey.

We investigated the roles of food shortage and predation in anticipated breeding failure of black-legged kittiwakes Rlssa trldactyla at Great Island, Kr~tless Bay, Newfoundland, Canada In 1992 and 1993, following widespread failure in 1991 Reduced and delayed availability of capelin Mallotus villosus, plus elimination of previously plentiful fish offal and discards following an eastern Canadian groundfish moratorium in 1992, induced food-stress on kitt~wakes and on large predatory Larus gulls. Breeding was late, a low proportion of pairs laid eggs, and egg and clutch sizes were small, indicating that feeding condlt~onsfo r kittiwakes were poor early in the season. Extreme food-stress resulted in low breed~ng success of Larns gulls that turned to kittiwake eggs as an alternate food source. Forced egg predation by great black-backed gulls Larus marinus was the primary cause of low hatching success (10 to 11 %) in both years. Durations of incubation and chick-rearing shifts decreased following the inshore arrival of capelin, and chicks that hatched after capelin arrival survived longer than earlier hatched chicks. Unattended nests were uncommon, probably in response to predation. In 1992, earlier hatching, later capelin arrival, and apparent lack of alternate prey resulted in many chicks starving and poor fledging success (7%). In 1993, food appeared to be more available both before and after capelin arrival, parents were able to provision chicks, and fledging success was normal (68%) The interactive effects of food shortage and predation have important linplications for the use of kittiwakes as indicator species and for the indirect effects of fishery activities on seabird interactions. Kittiwake productivity also reflects the resource base of their predators and caution is required when linking kittiwake breeding success to prey abundance. Moreover, fishery activities, such as the eastern Canadian groundfish morator~umth at eliminated fish discards and offal for large scavenging gulls, can have profound second-order effects on other seabird species that are preyed on by scavengers.

Walleye pollock Theragra chalcogramma are important prey of piscivorous seablrds at offshore breeding colonies in the southeastern Bering Sea. The reproductive success of kittiwakes Rissa spp. is related to the abundance of juvenile pollock. It is proposed that poor pollock recruitment in recent years, as determ~ned by fisheries surveys, led to persistent kittiwake breeding failures in 1981-84. Declines in numbers of k~ttiwakes and other piscivorous seabirds at 2 colonies also may be related to the decline in pollock abundance. In contrast, planktivorous seabirds, which possibly compete with juvenile pollock for zooplankton, particularly copepods, might benefit from a low abundance of pollock. A conceptual model of food limitation and trophic interactions at several levels in the offshore pelagic food web of the eastern Bering Sea can be developed by relating relations between seabirds and their prey to ( l ) the high grazing efficiency of the herbivorous zooplankton community, which is dominated by large calanoid copepods, (2) estimates of a high annual loss of copepods, presumably to vertebrates, and (3) regional carbon budgets. The possibility that populations of several species respond to changes in pollock abundance should be considered in management decisions for the commercial pollock fishery

Records of Fulmar Fulmams glacialis, Sooty Shearwater Puffinus griseus, Gannet Sula bassana and Kittiwake Rissa tridactyla, off Kullen in south Sweden, in the decade 1970 to 1979 have been analyzed with respect to meteorological conditions. A causal model describing the occurrence of flap-gliding pelagic seabirds off Kullen is proposed, based upon evidence of (1) close association of these birds with eastward travelling deeper cyclones; (2) restrictions of bird movements due to certain wind directions and velocities; (3) absence of documented cyclonic centre passages south of Latitude 58ON at Longitude 10° in connection with observations of birds; (4) earlier flight behaviour studies. A clockwise movement of birds in the Kattegat is ascribed to the interaction of (a) prevailing wind conditions in cyclones, (b) inertia of wave topography, (c) the birds' flight technique. The apparent conformity between the successive clockwise coastal pattern of movement of flap-gliding pelagic seabirds in the Kattegat and the North Sea is considered.