The migratory movements of seabirds (especially smaller species) remain poorly understood, despite their role as harvesters of marine ecosystems on a global scale and their potential as indicators of ocean health. Here we report a successful attempt, using miniature archival light loggers (geolocators), to elucidate the migratory behaviour of the Manx shearwater Puffinus puffinus, a small (400 g) Northern Hemisphere breeding procellariform that undertakes a trans-equatorial, trans-Atlantic migration. We provide details of over-wintering areas, of previously unobserved marine stopover behaviour, and the long-distance movements of females during their pre-laying exodus. Using salt-water immersion data from a subset of loggers, we introduce a method of behaviour classification based on Bayesian machine learning techniques. We used both supervised and unsupervised machine learning to classify each bird's daily activity based on simple properties of the immersion data. We show that robust activity states emerge, characteristic of summer feeding, winter feeding and active migration. These can be used to classify probable behaviour throughout the annual cycle, highlighting the likely functional significance of stopovers as refuelling stages.

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The interaction with water of protein-resistant monolayers (SAMs), self-assembled from (triethylene glycol) terminated thiol HS(CH2)11(OCH2CH2)3OMe solutions, was studied using in and ex situ polarization-modulated Fourier transform infrared spectroscopy. In particular, shifts in the position of the characteristic C-O-C stretching vibration were observed after the monolayers had been exposed to water. The shift in frequency increased when the SAM was observed in direct contact with a thin layer of water. It was found that the magnitude of the shift also depended on the surface coverage of the SAM. These findings suggest a rather strong interaction of oligo(ethylene glycol) SAMs with water and indicate the penetration of water into the upper region of the monolayer.

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SignificanceProcellariiform seabirds homing from distant foraging locations present a natural situation in which the homing route can become obstructed by islands or peninsulas because birds will not travel long distances over land. By measuring initial orientation from Global Positioning System (GPS) tracks during homing, we found that the Manx shearwater fails to encode such obstacles while homing, implying a navigation system that encodes the direction of home rather than a learned route. Nonetheless, shearwaters timed their journeys home, implying that their navigational system provides them with information about both direction and distance home, providing evidence that for routine, yet long-distance navigation, seabirds probably ascertain homeward direction by comparing their current position and the location of home with 2 or more intersecting field gradients.

There is increasing evidence for impacts of light pollution on the physiology and behaviour of wild animals. Nocturnally active Procellariiform seabirds are often found grounded in areas polluted by light and struggle to take to the air again without human intervention. Hence, understanding their responses to different wavelengths and intensities of light is urgently needed to inform mitigation measures. Here, we demonstrate how different light characteristics can affect the nocturnal flight of Manx shearwaters Puffinus puffinus by experimentally introducing lights at a colony subject to low levels of light pollution due to passing ships and coastal developments. The density of birds in flight above the colony was measured using a thermal imaging camera. We compared number of flying shearwaters under dark conditions and in response to an artificially introduced light, and observed fewer birds in flight during ‘light-on’ periods, suggesting that adult shearwaters were repelled by the light. This effect was stronger with higher light intensity, increasing duration of ‘light-on’ periods and with green and blue compared to red light. Thus, we recommend lower light intensity, red colour, and shorter duration of ‘light-on’ periods as mitigation measures to reduce the effects of light at breeding colonies and in their vicinity.

To improve risk assessment of the spread of invasive species and establish the coherence and connectivity of marine protected area (MPA) networks, there is a need to establish the spatial and temporal pathways of larval dispersal and associated recruitment and persistence of breeding populations (ABSTRACT Aim To evaluate whether natural larval transport and behaviour alone can explain the pattern of invasion and establishment of the non-indigenous Manila clam, Ruditapes philippinarum (Adams & Reeve, 1850), and its spread beyond the point of introduction in the UK.Location The study is focused on Poole Harbour, south England, the point of introduction of the Manila clam in the UK.Methods We use fine-resolution hydrodynamic models coupled with a water salinity model and an individual behaviour model of Manila clam larvae. The model was informed by experimental studies on the vertical response of larvae to salinity and field studies of the species in its natural and new environments.Results Variations in the behavioural response of larvae to salinity in the model considerably affected the retention of clam larvae within the harbour. High levels of predicted larval retention occurred in two of five zones in the harbour when the salinity target was set at 17 practical salinity units. Persistently high densities of adult clams and recruits are accurately predicted in these regions.Main conclusions Even within a relatively small region such as Poole Harbour, there is both localized retention of larvae or 'closed' areas and areas that are considerably more 'open' and potentially connected. The behavioural response of larvae to salinity significantly affected the degree of retention and 'openness' of the harbour to this species. Although, through natural transport, larvae could theoretically reach the next available habitat within the duration of their pelagic stage our study indicates that areas of sufficiently reduced salinity may be necessary for sufficient retention, recruitment and establishment of new adult populations in estuaries. High resolution hydrodynamic models, coupled with larval behaviour, can accurately simulate and predict biological invasion along complex coastlines and contribute to risk assessment of the introduction of nonindigenous species for aquaculture and spatial management of marine protection.