Does climate change impact directly on breeding seabirds?

Many seabird populations are declining, and climate change is thought to play an important role in this (Mitchell et al. 2020, Orgeret et al. 2022). Studies so far have mainly focused on the hypothesis that the impact of climate change on marine top predators, such as seabirds, acts indirectly through impacting the quantity, quality and timing of their prey (Sydeman et al. 2015). However, as seabirds tend to breed in highly exposed breeding sites at the height of summer, they are also likely to be highly vulnerable to direct effects of climate change (Oswald & Arnold 2012). In line with this, the few studies that have been conducted suggest that the direct effects on fitness could be large (e.g. Salzman 1982; Cook et al. 2020; Choy et al. 2021; Holt & Boersma 2022; Quintana et al. 2022), but the underlying physiological and behavioural effects remains largely unexplored. A better understanding of how climate change will impact seabirds is essential for effective conservation management of these species (Hakkinen et al. 2022).
Endothermic organisms, such as seabirds, are adapted to the thermal environment they have previously experienced. Relative increases in temperature beyond the typical thermal conditions they are adapted to can challenge their thermoregulatory ability. They employ a suite of behavioural and physiological responses to avoid overheating when air temperature and/or solar radiation increase above the thermal environment they are adapted to, which with predicted climate change will occur more and more frequently. That increasing thermoregulatory activity can have consequences for survival, work rate and reproductive success has been demonstrated even in temperate climates (Andreasson et al. 2020). Birds experiencing high air temperatures can allow for a controlled hyperthermia, which can have detrimental physiological effects including dehydration and oxidative stress, maintain a constant body temperature through increasing heat dissipation by evaporative cooling, which is expensive in terms of energy and water (Whitfield et al. 2015), or reduce heat gain and/or production through e.g. seeking shade and lowering work rate, which may reduce opportunities to provision and protect offspring. As such, thermoregulation must be traded-off with other competing demands such as self-maintenance and offspring provisioning (temperature-dependent behavioural trade-offs, Conradie et al. 2019).

Hence, the risks of climate warming for seabirds may include (i) environmental conditions exceeding heat tolerance and dehydration tolerance limits (thermal physiology) and (ii) temperature-dependent behavioural trade-offs. However, as of yet very little is known about how seabirds in temperate climates respond to rising temperatures, or what the demographic consequences of these effects may be for seabird populations.

This project will therefore look at the direct impact of climate warming on breeding seabirds in temperate climates at different scales and in different species by exploring: (i) variation between colony sites and species in thermal microclimate, and how it relates to the colony’s breeding success and long-term trends in breeding numbers; (ii) between-nest variation in thermal stress of chicks and adults on the nest and how it relates to chick growth and parental provisioning behaviour in two species with contrasting ecologies and (iii) potential long-term demographic consequences of direct effects of climate warming on seabird populations.

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Image Captions

Thermal image of a Guillemot at Stora Karlsö (image A. Olin)


To address the key objectives:
(i) The project will characterise the locations of cliff-nesting seabird colonies in the British Isles in relation to prevailing air temperature and solar exposure and relate the colony’s thermal climate to occupancy, population-level breeding success and long-term population trends available from the Seabird Monitoring Programme. Where available, within-site variation could also be explored. This will add to our understanding of which cliff-nesting species may be most vulnerable to direct effects of increased temperatures on breeding sites.
(ii) The project will characterise variation in thermal microclimate between nest sites within colonies and measure the impact of nest site microclimate variation on thermal stress of chicks and adults. This part of the study is planned to be carried out on ground-nesting European shags (Phalacrocorax aristotelis) on the west coast of Scotland (Grant et al. 2013) and on common guillemots (Uria aalge) in the Baltic Sea, where individual nest sites are accessible on an artificial cliff (Hentati-Sundberg et al. 2012). Preliminary data from the guillemot colony and a Scottish gannet colony, as well as previous work on closely related species on other continents (Cook et al. 2020; Choy et al. 2021; Quintana et al. 2022), suggest that high temperatures are likely to impact the behaviour and breeding success of these species negatively. The purpose of using both a species laying its egg directly on the cliff ledge and a species building a nest on the ground is to provide more generalisable insights, as the two species may experience very different microclimates. The project will use temperature loggers to measure nest microclimate throughout the nesting period and in shags use artificial shelters to alter nest microclimate. The birds’ body temperature and heat transfer will be measured through thermal imaging, which also makes it possible to identify which body regions and postures play a role in heat transfer (McCafferty 2013, Jerem et al. 2018, Tattersall et al. 2018). The estimated level of heat stress will then be related to offspring growth, parent and offspring behaviour at the nest, and parental provisioning, all of which will be recorded using nest cameras.
(iii) The project will explore the potential demographic consequences of direct temperature effects on breeding seabirds observed as part of objective (ii). Such effects, which preliminary data support, will be incorporated into a demographic model to assess their impact at the population level. The demographic model will be run under different adult survival scenarios. This approach can be used to explore if and at what point direct temperature effects may start to have an impact on seabird demographics under different climate change scenarios.
In case there is restricted access to field sites because of avian influenza, objective (i) is based on long-term public data already available to the student and additional data on thermal microclimate and breeding success from the guillemot study in the Baltic Sea can be made available.

Project Timeline

Year 1

Preparing a literature review on thermoregulation and direct effects of temperature on endotherms in general and seabirds in particular; PGR Training Programme. Between-site comparison of thermal microclimate of UK seabird cliffs and analysis of existing long-term seabird data (objective i); manuscript preparation.

Year 2

Preparation for the first field season involving characterising thermal microclimates of nest sites and measuring thermal stress in birds (objective ii). Field data collection and analysis. Initiate demographic modelling (objective iii).

Year 3

Preparation for and completion of the second field season, incorporating insights gained from the first season. Data analysis and manuscript preparation; presenting results at conferences. Further development of the demographic model.

Year 3.5

Final analytical and modelling work and completion of thesis.

& Skills

This project will develop the student’s scientific training in field ecology, physiology and behaviour, study design, data analysis and interpretation and scientific writing. The student will receive training and gain skills and expertise in: designing field studies aimed at testing effects of environmental factors on an organism’s performance, deployment of data loggers and interpretation of measurements to characterise physiologically relevant microclimates, the use of thermal imaging (a method with a range of applications in ecology and physiology) to infer body temperature and heat transfer, the use of time-lapse cameras and cctv cameras to record and interpret behaviour, a range of advanced statistical analyses (mixed-effects models, broken stick models for non-linear relationships between environment and physiological and behavioural variables; demographic and heat transfer modelling, power analysis).
The student will also receive further training opportunities from the broad generic skills training available through the University of Glasgow’s postgraduate training programmes and the specific environmental science training provided within the IAPETUS2 Doctoral Training Partnership framework. The international collaboration and the use of data collected by a variety of institutions will provide the student with excellent network opportunities within the area of study, and additional training in skills not covered at the host institution and the IAPETUS2 network.

References & further reading

Andreasson F, Nilsson J-Å & Nord A 2020 Avian Reproduction in a Warming World. Frontiers in Ecology and Evolution 8,576331.

Caswell, H 2006 Matrix population models. Construction, analysis and interpretation. Sinauer Associates.

Choy ES, O’Connor RS, Gilchrist HG, Hargreaves AL, Love OP, Vézina F & Elliott, KH 2021 Limited heat tolerance in a cold-adapted seabird: implications of a warming Arctic. Journal of Experimental Biology 224,jeb242168

Conradie SR, Woodborne SM, Cunningham SJ, McKechnie AE 2019 Chronic, sublethal effects of high temperatures will cause severe declines in southern African arid-zone birds during the 21st century. PNAS 116,14065-14070

Cook TR, Martin R, Roberts J, Häkkinen H, Botha P, Meyer C, Sparks E, Underhill LG, Ryan PG, Sherley RB 2020 Parenting in a warming world: thermoregulatory responses to heat stress in an endangered seabird. Conservation Physiology 8,coz109

Grant D, Robertson D, Nager RG & McCracken D 2013 The status of breeding gulls on Lady Isle, Ayrshire, 2012. Scottish Birds 33,298–307

Hakkinen H, Petrovan SO, Sutherland WJ, Dias MP, Ameca EI, Oppel S, Ramírez I, Lawson B, Lehikoinen A, Bowgen KM, Taylor NG & Pettorelli N 2022 Linking climate change vulnerability research and evidence on conservation action effectiveness to safeguard European seabird populations. Journal of Applied Ecology 59,1178–1186

Hentati-Sundberg J, Österblom H, Kadin M, Jansson Å & Olsson O. 2012. The Karlsö murre lab methodology can stimulate innovative seabird research. Marine Ornithology 40,11-16

Holt KA & Boersma PD 2022 Unprecedented heat mortality of Magellanic Penguins. Ornithological Applications 124,1–12

Jerem P, Jenni-Eiermann S, Herborn K, McKeegan D, McCafferty DJ & Nager RG 2018 Eye region surface temperature reflects both energy reserves and circulating glucocorticoids in a wild bird. Scientific Report 8,1907

McCafferty, DJ 2013 Applications of thermal imaging in avian science Ibis 155,4–15

Met Office 2019 UK Climate Projections: Headline Findings https://www.metoffice.gov.uk/binaries/content/assets/metofficegovuk/pdf/research/ukcp/ukcp-headline-findings-v2.pdf

Mitchell I, Daunt F, Frederiksen M & Wade K 2020 Impacts of climate change on seabirds, relevant to the coastal and marine environment around the UK. MCCIP Science Review 2020,382–399

Orgeret F, Thiebault A, Kovacs KM, Lyderse C, Hindell MA, Thompson SA. Sydeman WJ & Pistorius PA 2022 Climate change impacts on seabirds and marine mammals: The importance of study duration, thermal tolerance and generation time. Ecology Letter 25,218-239

Oswald SA & Arnold JM 2012 Direct impacts of climatic warming on heat stress in endothermic species: seabirds as bioindicators of changing thermoregulatory constraints. Integrative Zoology 7,121–136

Quintana F, Uhart MM, Gallo L, Mattera MB, Rimondi A & Gómez‑Laich A 2022 Heat-related massive chick mortality in an Imperial Cormorant Leucocarbo atriceps colony from Patagonia, Argentina. Polar Biology 45,275–284

Salzman AG 1982 The Selective importance of heat stress in gull nest location. Ecology 63,742-751

Sydeman WJ, Poloczanska E, Reed TE & Thompson SA 2015 Climate change and marine vertebrates Science 350, 772-777

Tattersall GJ, Chaves JA & Danner RM. 2018. Thermoregulatory windows in Darwin’s finches. Functional Ecology 32,358-368

Whitfield MC, Smit B, McKechnie AE & Wolf BO 2015 Avian thermoregulation in the heat: scaling of heat tolerance and evaporative cooling capacity in three southern African arid-zone passerines Journal of Experimental Biology 218,1705-1714

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