Loading...
34 results
Search Results
Now showing 1 - 10 of 34
- Quantifying annual spatial consistency in chick-rearing seabirds to inform important site identificationPublication . Beal, Martin; Catry, Paulo; Phillips, Richard A.; Oppel, Steffen; Arnould, John P.Y.; Bogdanova, Maria I.; Bolton, Mark; Carneiro, Ana P.B.; Clatterbuck, Corey; Conners, Melinda; Daunt, Francis; Delord, Karine; Elliott, Kyle; Fromant, Aymeric; Granadeiro, José P.; Green, Jonathan A.; Halsey, Lewis; Hamer, Keith C.; Ito, Motohiro; Jeavons, Ruth; Kim, Jeong-Hoon; Kokubun, Nobuo; Koyama, Shiho; Lane, Jude V.; Lee, Won Young; Matsumoto, Sakiko; Orben, Rachael; Owen, Ellie; Paiva, Vitor H.; Patterson, Allison; Pollock, Christopher J.; Ramos, Jaime A.; Sagar, Paul; Sato, Katsufumi; Shaffer, Scott A.; Soanes, Louise; Takahashi, Akinori; Thompson, David R.; Thorne, Lesley; Torres, Leigh; Watanuki, Yutaka; Waugh, Susan M.; Weimerskirch, Henri; Whelan, Shannon; Yoda, Ken; Xavier, José C.; Dias, Maria P.Animal tracking has afforded insights into patterns of space use in numerous species and thereby informed area-based conservation planning. A crucial consideration when estimating spatial distributions from tracking data is whether the sample of tracked animals is representative of the wider population. However, it may also be important to track animals in multiple years to capture changes in distribution in response to varying environmental conditions. Using GPS-tracking data from 23 seabird species, we assessed the importance of multi-year sampling for identifying important sites for conservation during the chick-rearing period, when seabirds are most spatially constrained. We found a high degree of spatial overlap among distributions from different years in most species. Multi-year sampling often captured a significantly higher portion of reference distributions (based on all data for a population) than sampling in a single year. However, we estimated that data from a single year would on average miss only 5 % less of the full distribution of a population compared to equal-sized samples collected across three years (min: −0.3 %, max: 17.7 %, n = 23). Our results suggest a key consideration for identifying important sites from tracking data is whether enough individuals were tracked to provide a representative estimate of the population distribution during the sampling period, rather than that tracking necessarily take place in multiple years. By providing an unprecedented multi-species perspective on annual spatial consistency, this work has relevance for the application of tracking data to informing the conservation of seabirds.
- Multispecies tracking reveals a major seabird hotspot in the North AtlanticPublication . Davies, Tammy E.; Carneiro, Ana P.B.; Tarzia, Marguerite; Wakefield, Ewan; Hennicke, Janos C.; Frederiksen, Morten; Hansen, Erpur Snær; Campos, Bruna; Hazin, Carolina; Lascelles, Ben; Anker‐Nilssen, Tycho; Arnardóttir, Hólmfríður; Barrett, Robert T.; Biscoito, Manuel; Bollache, Loïc; Boulinier, Thierry; Catry, Paulo; Ceia, Filipe R.; Chastel, Olivier; Christensen‐Dalsgaard, Signe; Cruz‐Flores, Marta; Danielsen, Jóhannis; Daunt, Francis; Dunn, Euan; Egevang, Carsten; Fagundes, Ana Isabel; Fayet, Annette L.; Fort, Jérôme; Furness, Robert W.; Gilg, Olivier; González‐Solís, Jacob; Granadeiro, J. P.; Grémillet, David; Guilford, Tim; Hanssen, Sveinn Are; Harris, Michael P.; Hedd, April; Huffeldt, Nicholas Per; Jessopp, Mark; Kolbeinsson, Yann; Krietsch, Johannes; Lang, Johannes; Linnebjerg, Jannie Fries; Lorentsen, Svein‐Håkon; Madeiros, Jeremy; Magnusdottir, Ellen; Mallory, Mark L.; McFarlane Tranquilla, Laura; Merkel, Flemming R.; Militão, Teresa; Moe, Børge; Montevecchi, William A.; Morera‐Pujol, Virginia; Mosbech, Anders; Neves, Verónica; Newell, Mark A.; Olsen, Bergur; Paiva, Vitor H.; Peter, Hans‐Ulrich; Petersen, Aevar; Phillips, Richard A.; Ramírez, Iván; Ramos, Jaime A.; Ramos, Raül; Ronconi, Robert A.; Ryan, Peter G.; Schmidt, Niels Martin; Sigurðsson, Ingvar A.; Sittler, Benoît; Steen, Harald; Stenhouse, Iain J.; Strøm, Hallvard; Systad, Geir H. R.; Thompson, Paul; Thórarinsson, Thorkell L.; Bemmelen, Rob S.A.; Wanless, Sarah; Zino, Francis; Dias, Maria P.The conservation of migratory marine species, including pelagic seabirds, is challenging because their movements span vast distances frequently beyond national jurisdictions. Here, we aim to identify important aggregations of seabirds in the North Atlantic to inform ongoing regional conservation efforts. Using tracking, phenology, and population data, we mapped the abundance and diversity of 21 seabird species. This revealed a major hotspot associated with a discrete area of the subpolar frontal zone, used annually by 2.9–5 million seabirds from ≥56 colonies in the Atlantic: the first time this magnitude of seabird concentrations has been documented in the high seas. The hotspot is temporally stable and amenable to site-based conservation and is under consideration as a marine protected area by the OSPAR Commission. Protection could help mitigate current and future threats facing species in the area. Overall, our approach provides an exemplar data-driven pathway for future conservation efforts on the high seas.
- An ontogenetic perspective on migratory strategy of a long-lived pelagic seabird: Timings and destinations change progressively during maturationPublication . Letizia, Campioni; Dias, Maria P.; Granadeiro, José Pedro; Catry, PauloThe processes that drive the ontogeny of migratory strategies in long-lived animals with slow maturation remain enigmatic. While some short-lived migrants are known or believed to repeat the same migratory patterns throughout their lives, little is known on the time required for immature long-lived migrants to progressively acquire adult-like migratory behaviours, or which aspects take longer to refine during the maturation process. Here, we studied the ontogeny of long-distance migratory strategies and related patterns of spatial distribution in a long-lived seabird species during the annual cycle. To do so, we deployed light-level geolocators on 4- to 9-year-old immature Cory's shearwaters (Calonectris borealis) and on breeding adults. We revealed that migratory timings and destinations of young shearwaters progressively changed with age. The effect of ageing was remarkably evident on spring migratory performance and phenology. Birds gradually shortened the duration of the non-breeding period by advancing departure date and reducing travelling time, which resulted in a sequential arrival at the colony of the various age contingents. Ageing immatures gradually changed from a more exploratory strategy to a more conservative way of exploiting resources, reducing both their year-round spatial spread across oceanic domains and the total distance travelled. Immatures always performed a trans-equatorial migration to the Southern Hemisphere, contrasting with 17% of the adults which remained in the North Atlantic year-round. Finally, during the breeding season immatures were widely dispersed through the North Atlantic reducing their overlap with breeding adults. Our long-term study provides empirical support to the hypothesis that in long-lived species, the refinement of migratory behaviour and year-round spatial distribution is a progressive process mediated by age and experience, where life stage constraints and competition for resources may also play a role. The emerging pattern suggests that for some avian taxa, the ontogeny of migratory strategy is a prolonged, complex and dynamic process.
- Absence of haemosporidian parasite infections in the long-lived Cory’s shearwater: evidence from molecular analyses and review of the literaturePublication . Campioni, Letizia; Martínez-de la Puente, Josué; Figuerola, Jordi; Granadeiro, José P.; Silva, Mónica C.; Catry, PauloThe apparent scarcity or absence of blood parasites in some avian groups, such as seabirds, has been related to intrinsic and extrinsic factors including host immunological capacity, host-parasite assemblage, and ecological parameters, but also to reduced sensitivity of some methods to detect low parasite prevalence/intensities of infection. Here, we examined the haemosporidian parasite prevalence in a breeding population of Cory's shearwater Calonectris diomedea borealis, a long-distance migrant seabird, nesting in the Macaronesian region, in the Eastern Atlantic. Previous studies on Calonectris diomedea complex were based on small sample sizes providing weak evidence for a lack of infections by haemoparasites. Here, we investigated the presence of both parasite infections in C. d. borealis and larvae of potential mosquito vectors on the area. By employing a PCR-based assay, we extensively examined the prevalence of blood parasites belonging to the genera Plasmodium, Haemoproteus, and Leucocytozoon in 286 individuals from different life stages (i.e., chicks, immatures, sabbatical, and breeding adults), facing their specific energetic trade-offs (immunological functions vs. life history activities). We sampled immatures and adult shearwaters, of different sexes, ages, and migratory origins, from two sub-colonies. None of the sampled individuals were infected by these parasites, supporting the hypothesis that there was no in situ or ex situ transmission of vector-borne parasites in marine habitats irrespective of host's life stage and in spite of the presence of the potential Plasmodium vector Culiseta longiareolata breeding in the area. These results suggest that the lack of transmission of haemosporidian parasites on Selvagem Grande may be related to the lack of suitable dipteran vectors at the study sites, which may result from the geographic isolation of this area.
- Tunas off northwest Africa: The epipelagic diet of The Bigeye and Skipjack tunasPublication . Romero, Joana; Catry, Paulo; Hermida, Margarida; Neves, V C; Cavaleiro, Bárbara; Gouveia, Lídia; Granadeiro, José PedroTunas are among the most exploited top predators worldwide, with negative impacts on some of their stocks. Changes in their population abundance can impact marine food-webs and have the potential to alter entire ecosystems. To better understand the impacts of the exploitation of tuna stocks in the most critical habitats, basic knowledge on the diet of these species in each region is required. Here, we describe the diet of the two most fished tuna species in the archipelago of Madeira, the Bigeye tuna Thunnus obesus and the Skipjack tuna Katsuwonus pelamis, based on stomach contents analysis. To gain further insights into the diet, and also better assess the possible bias caused by the occurrence of live bait in stomachs, we compared tuna mercury values with those of two other predators with similar diets that are not directly targeted by fisheries, and with Bigeye and Skipjack tunas from other ocean basins. Bigeye tunas fed mostly on Atlantic chub mackerel Scomber colias and mackerel Trachurus sp., which together contributed with 85% of total prey weight. Only 7.5% of prey weight was constituted by mesopelagic prey, including myctophids and cephalopods. Skipjack tunas had an epipelagic diet (NF = 97%), with the Atlantic chub mackerel representing half of the total prey weight, despite Longspine snipefish Macroramphosus scolopax and Sand smelt Atherina sp. accounting for 62.9% of the total number of prey. There were interannual variations in diet likely linked to interannual pelagic community shifts. Bait did not bias the results of the stomach analysis of these tunas and bait species were observed to be part of the natural diet of both tuna species. Baseline data provided by this study should allow for more informed decisions for an efficient ecosystem-based fisheries management.
- Environmental variability directly affects the prevalence of divorce in monogamous albatrossesPublication . Ventura, Francesco; Granadeiro, José P.; Lukacs, Andor; Kuepfer, Amanda; Catry, PauloIn many socially monogamous species, divorce is a strategy used to correct for sub-optimal partnerships and is informed by measures of previous breeding performance. The environment affects the productivity and survival of populations, thus indirectly affecting divorce via changes in demographic rates. However, whether environmental fluctuations directly modulate the prevalence of divorce in a population remains poorly understood. Here, using a longitudinal dataset on the long-lived black-browed albatross (Thalassarche melanophris) as a model organism, we test the hypothesis that environmental variability directly affects divorce. We found that divorce rate varied across years (1% to 8%). Individuals were more likely to divorce after breeding failures. However, regardless of previous breeding performance, the probability of divorce was directly affected by the environment, increasing in years with warm sea surface temperature anomalies (SSTA). Furthermore, our state-space models show that warm SSTA increased the probability of switching mates in females in successful relationships. For the first time, to our knowledge, we document the disruptive effects of challenging environmental conditions on the breeding processes of a monogamous population, potentially mediated by higher reproductive costs, changes in phenology and physiological stress. Environmentally driven divorce may therefore represent an overlooked consequence of global change.
- Oceanic seabirds chase tropical cyclonesPublication . Ventura, Francesco; Sander, Neele; Catry, Paulo; Wakefield, Ewan; De Pascalis, Federico; Richardson, Philip L; Granadeiro, José P.; Silva, Monica C.; Ummenhofer, Caroline C.In late summer and autumn, the passage of intense tropical cyclones can profoundly perturb oceanic and coastal ecosystems. Direct negative effects on individuals and marine communities can be dramatic, especially in the coastal zone,1–4 but cyclones can also enhance pelagic primary and secondary production.5–9 However, cyclone impacts on open ocean marine life remain poorly understood. Here, we investigate their effects on the foraging movements of a wide-ranging higher predator, the Desertas petrel (Pterodroma deserta), in the mid-latitude North Atlantic during hurricane season. Contrary to previously studied pelagic seabirds in tropical and mid-latitude regions,10,11 Desertas petrels did not avoid cyclones by altering course, nor did they seek calmer conditions within the cyclone eye. Approximately one-third of petrels tracked from their breeding colony interacted with approaching cyclones. Upon encountering strong winds, the birds reduced ground speed, likely by spending less time in flight. A quarter of birds followed cyclone wakes for days and over thousands of kilometers, a behavior documented here for the first time. Within these wakes, tailwind support was higher than along alternative routes. Furthermore, at the mesoscale (hours–weeks and hundreds of kilometers), sea surface temperature dropped and surface chlorophyll sharply increased, suggesting direct effects on ocean stratification, primary production, and therefore presumably prey abundance and accessibility for surface-feeding petrels. We therefore hypothesize that cyclone wakes provide both predictably favorable wind conditions and foraging opportunities. As such, cyclones may have positive net effects on the demography of many mid-latitude pelagic seabirds and, likely, other marine top-predators.
- Corrigendum to “Quantifying annual spatial consistency in chick-rearing seabirds to inform important site identification” [Biol. Conserv. 281 (2023) 109994]Publication . Beal, Martin; Catry, Paulo; Phillips, Richard A.; Oppel, Steffen; Arnould, John P.Y.; Bogdanova, Maria; Bolton, Mark; Carneiro, Ana P.B.; Clatterbuck, Corey; Conners, Melinda; Daunt, Francis; Delord, Karine; Elliott, Kyle; Fromant, Aymeric; Granadeiro, José P.; Green, Jonathan A.; Halsey, Lewis; Hamer, Keith C.; Ito, Motohiro; Jeavons, Ruth; Kim, Jeong-Hoon; Kokubun, Nobuo; Koyama, Shiho; Lane, Jude V; Lee, Won Young; Matsumoto, Sakiko; Orben, Rachael; Owen, Ellie; Paiva, Vitor H.; Patterson, Allison; Pollock, Christopher J.; Ramos, Jaime A.; Sagar, Paul; Sato, Katsufumi; Shaffer, Scott; Soanes, Louise; Takahashi, Akinori; Thompson, David; Thorne, Lesley; Torres, Leigh; Watanuki, Yutaka; Waugh, Susan M.; Weimerskirch, Henri; Whelan, Shannon; Yoda, Ken; Xavier, J. C.; Dias, Maria P.Animal tracking has afforded insights into patterns of space use in numerous species and thereby informed areabased conservation planning. A crucial consideration when estimating spatial distributions from tracking data is whether the sample of tracked animals is representative of the wider population. However, it may also be important to track animals in multiple years to capture changes in distribution in response to varying environmental conditions. Using GPS-tracking data from 23 seabird species, we assessed the importance of multi-year sampling for identifying important sites for conservation during the chick-rearing period, when seabirds are most spatially constrained. We found a high degree of spatial overlap among distributions from different years in most species. Multi-year sampling often captured a significantly higher portion of reference distributions (based on all data for a population) than sampling in a single year. However, we estimated that data from a single year would on average miss only 5 % less of the full distribution of a population compared to equal-sized samples collected across three years (min: − 0.3 %, max: 17.7 %, n = 23). Our results suggest a key consideration for identifying important sites from tracking data is whether enough individuals were tracked to provide a representative estimate of the population distribution during the sampling period, rather than that tracking necessarily take place in multiple years. By providing an unprecedented multi-species perspective on annual spatial consistency, this work has relevance for the application of tracking data to informing the conservation of seabirds.
- Working the day or the night shift? Foraging schedules of Cory’s shearwaters vary according to marine habitatPublication . Dias, Paulo Sousa; Granadeiro, J. P.; Catry, PauloThe diel vertical migration of zooplankton and many other organisms is likely to affect the foraging behaviour of marine predators. Among these, shallow divers, such as many seabirds, are particularly constrained by the surface availability of prey items. We analysed the atsea activity of a surface predator of epipelagic and mesopelagic prey, Cory’s shearwater Calonectris diomedea, on its several wintering areas (spread throughout the temperate Atlantic Ocean and the Agulhas Current). Individual shearwaters were mainly diurnal when wintering in warmer and shallower waters of the Benguela, Agulhas and Brazilian Currents, and comparatively more nocturnal in colder and deeper waters of the Central South Atlantic and the Northwest Atlantic. Nocturnality also correlated positively with bathymetry and negatively with sea-surface temperature within a single wintering area. This is possibly related to the relative availability of epipelagic and mesopelagic prey in different oceanic sectors, and constitutes the first evidence of such flexibility in the daily routines of a top marine predator across broad spatial scales, with clear expression at population and individual levels
- Coastal waters of a marine protected area of the Bijagós Archipelago, West Africa, shelter juvenile fishes of economic and ecological importancePublication . Correia, Edna; Granadeiro, J. P.; Regalla De Barros, Aissa; Catry, PauloIn many marine ecosystems small pelagic fish exert a crucial role in controlling the dynamics of the community, mainly due to their high biomass at intermediate levels of the food web. These fish use coastal marine ecosystems as nursery areas, but also to forage and to avoid predation or competition. We studied spatial, seasonal, lunar and diel variations in a coastal fish community from a marine protected area of the Bijagós Archipelago, Guinea-Bissau. Fish were sampled with 46 beach seine net sessions in 2015 and 2016. A total of 35 fish species of 25 families were captured. Fish abundance varied between years and seasons, with a higher abundance in the dry season, but not by lunar tide. Nonetheless, the community composition was broadly similar over the seasons, among islands and between lunar tides. Clupeidae, Haemulidae and Gerreidae were the most abundant fish families. Sardinella maderensis highly dominated the captures throughout the year, with catches much higher than any other species. The differences in abundance between seasons and years may be related with movements to or from the shore due to feeding activity or to avoid predation, or else to differences in recruitment between years. There were no significant diel differences in species richness and diversity, although higher numbers of fish were captured during daytime. For most species the majority of individuals captured were immature, highlighting the importance of the archipelago as nursery area for several species. These small pelagics, and particularly Sardinella maderensis, represent the main prey for several marine predators. Thus, the conservation of such fish species may be key for the management of the Bijagós Archipelago.