Does climate change impact directly on breeding seabirds?

Overview

Many seabird populations are declining, and climate change is thought to play an important role in this (Mitchell et al. 2020). Many studies have explored 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, little is known about direct physiological and behavioural effects of climate change on seabirds (e.g. Cook et al. 2020), and this project aims to increase our understanding of this topic.
Our climate is predicted to change over the coming decades with increasing temperatures, and increasing frequency of extreme weather events, such as heat waves (Met Office 2019). Higher air temperatures and frequency of heat waves may have direct effects on birds’ heat loads, and thus their energy and water balances, which has consequences for the growth and survival of the birds (reviewed in Andreasson et al. 2020). Extreme air temperatures during the breeding season could therefore negatively affect seabird breeding success, and an improved understanding of physiological links between weather and reproduction via changes in physiology need to be quantified in order to provide a better understanding of the full effects of climate change on seabirds.
Endothermic organisms can use a suite of behavioural and physiological responses to avoid overheating when air temperature increases. Organisms are adapted to the thermal environment they inhabit, and relative increases in temperature beyond the typical thermal conditions can challenge their thermoregulatory ability. Even when the temperature the birds experience does not appear to be dramatically high, consequences on survival, work rate and reproductive success have been demonstrated even in temperate climates (Andreasson et al. 2020). Birds experiencing high air temperatures can either allow for a controlled hyperthermia which can have detrimental physiological effects including dehydration and oxidative stress, or maintain a constant body temperature through increasing heat dissipation by evaporative cooling which is expensive to the bird both in terms of energy and water (Whitefield et al. 2015). Any costs of 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). Alternatively, birds may mitigate effects of high air temperatures by reducing heat gain and heat production, which can be achieved by seeking shade and lowering work rate, respectively, both of which reduce opportunities to provision offspring and hence affect offspring growth and survival. Seabirds that nest on cliffs or on bare ground have little opportunities to avoid incident solar radiation at the nest. This may make seabirds particularly vulnerable to increasing air temperatures and frequency of heat waves (Oswald & Arnold 2012). 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 on how seabirds in temperate climates respond to rising temperatures, or what the demographic consequences of these effects may have for seabird populations in temperate climates.
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 solar exposure 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.

Methodology

Methods to be used to address the objectives:
(i) The project will characterise the locations of cliff-nesting sites in relation to solar exposure and relate sites’ solar exposure to site occupancy and the colony’s breeding success and long-term trends in breeding numbers available from the Seabird Monitoring Programme. This will add to our understanding of which cliff-nesting species may be most vulnerable to direct effect of increased temperatures on breeding sites.
(ii) The project will characterise variation in nest thermal microclimate between nest sites within colonies and measure the impact of nest site microclimate variation on thermal stress of chicks and adults on the nest. This part of 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 common guillemots (Uria aalge) in the Baltic Sea, where individual nest sites are accessible at an artificial cliff (Hentati-Sundberg et al. 2012). The purpose of using two species is that they differ in how they could cope with thermal stress and provides more generalisable insights. The project will use temperature loggers to measure nest microclimate throughout the nesting period and 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 as well as parent and offspring behaviour at the nest which will be recorded using nest cameras, and temporal variation in parental provisioning.
(iii) The project also aims to explore the potential demographic consequences of the direct temperature effects on breeding seabirds observed in this study. Such effects, if found, will be incorporated into a demographic model (Caswell 2006) 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 a detectable impact on seabird demographics under different climate change scenarios.

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; manuscript preparation.

Year 2

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

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.

Training
& Skills

This project will develop the student 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 performance, deployment of data loggers and interpretation of measurements to characterise physiologically relevant microclimates, the use of thermal imaging (novel 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, and analysis of the resulting data; demographic modelling and power analysis.
The student will also receive further training opportunities from the broad generic skills training available through the University of Glasgow 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 & 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.

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, Hakkinen 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 R & McCracken D 2013 The status of breeding gulls on Lady Isle, Ayrshire, 2012. Scottish Birds 33,298-07

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

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 155,4-5

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

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

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

Further Information

For informal enquiries, contact: Ruedi Nager, ruedi.nager@glasgow.ac.uk, 0141 330 5976

Application procedure: For IAPETUS2 applications to the University of Glasgow please use the dedicated application portal: www.gla.ac.uk/ScholarshipApp (you will still need to submit your administrative details to the IAPETUS2 website as well).

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