An empirical investigation of risk-sensitivity in foraging flocks of Nutmeg Mannikins (Lonchura punctulata)

Foraging in a group allows for the exploitation of other individuals' food findings, often modeled as a producer-scrounger game. Producer-scrounger games assume that searching for food patches (producer) and for exploitation opportunities (scrounger) are mutually exclusive tactics, and predict that the proportion of scrounger in a group should reach a stable equilibrium where both tactics provide equal payoffs. A stochastic producer-scrounger model assumes that scrounger reduces the variability of intake and that animals minimize the probability of incurring an energy shortfall (risk-sensitive). Consequently, it predicts that the proportion of scrounger at SEF should depend on the animals' energy requirement. In experiment one, I tested the crucial assumption that producer yields a more variable intake than scrounger. I observed flocks of Lonchura punctulata foraging for hidden patches of seeds on a board, in an indoor aviary. At a short time scale, producer yielded a more variable intake than scrounger in 17/20 birds. Based on the cumulative probability distributions of intake rates, scrounger frequency should decline with decreasing energy reserves, the opposite predicted by the stochastic model. In experiment two 7/8 birds reduced their use of scrounger with decreasing energy reserves. I conclude that L. punctulata is sensitive to the variability of intake rate (risk-sensitive), but that the current stochastic producer-scrounger model does not apply to these birds

Altruistic defence behaviours in aphids

Background: Altruistic anti-predatory behaviours pose an evolutionary problem because they are costly to the actor and beneficial to the recipients. Altruistic behaviours can evolve through indirect fitness benefits when directed toward kin. The altruistic nature of anti-predatory behaviours is often difficult to establish because the actor can obtain direct fitness benefits, or the behaviour could result from selfish coercion by others, especially in eusocial animals. Non-eusocial parthenogenetically reproducing aphids form colonies of clone-mates, which are ideal to test the altruistic nature of anti-predatory defence behaviours. Many aphids release cornicle secretions when attacked by natural enemies such as parasitoids. These secretions contain an alarm pheromone that alerts neighbours (clone-mates) of danger, thereby providing indirect fitness benefits to the actor. However, contact with cornicle secretions also hampers an attacker and could provide direct fitness to the actor. Results: We tested the hypothesis that cornicle secretions are altruistic by assessing direct and indirect fitness consequences of smearing cornicle secretions onto an attacker, and by manipulating the number of clone-mates that could benefit from the behaviour. We observed parasitoids, Aphidius rhopalosiphi, foraging singly in patches of the cereal aphid Sitobion avenae of varied patch size (2, 6, and 12 aphids). Aphids that smeared parasitoids did not benefit from a reduced probability of parasitism, or increase the parasitoids' handling time. Smeared parasitoids, however, spent proportionately more time grooming and less time foraging, which resulted in a decreased host-encounter and oviposition rate within the host patch. In addition, individual smearing rate increased with the number of clone-mates in the colony. Conclusions: Cornicle secretions of aphids were altruistic against parasitoids, as they provided no direct fitness benefits to secretion-releasing individuals, only indirect fitness benefits through neighbouring clone-mates. Moreover, the use of cornicle secretions was consistent with their altruistic nature, because the occurrence of this behaviour increased with the size of indirect fitness benefits, the number of clone-mates that can benefit. This study provides evidence for a case of kin-directed altruistic defence outside eusocial animals

From Living Law to Global Legal Pluralism: Rethinking Traditions from a Century of Western Socio-Legal Studies

This paper notes certain key landmarks in the modern history of Western sociology of law. Taken together, these map developments that have given socio-legal studies some of its most influential and powerful theoretical ideas. But the paper asks how far such inherited ideas – and the research traditions they represent – are still useful in confronting the pluralistic, globalised and fragmented regulatory systems that proliferate today. How far can sociology of law maintain continuity with its past? This paper argues that it can maintain a strong continuity, but also that it must discard (or radically rework) some of its central inherited ideas that are coming to seem anachronistic in the face of contemporary socio-legal developments: especially developments relating to cultural pluralism, legal pluralism and transnational law

Automated detection and tracking of marine mammals : a novel sonar tool for monitoring effects of marine industry

Funding: The work was funded under the Scottish Government Demonstration Strategy (Project no. USA/010/14)and as part of the Department of Energy and Climate Change’s Offshore Energy Strategic Environmental Assessment programme, with additional resources from the Natural Environment Research Council (grant numbers: NE/R014639/1 and SMRU1001).1. Many marine industries may pose acute risks to marine wildlife. For example, tidal turbines have the potential to injure or kill marine mammals through collisions with turbine blades. However, the quantification of collision risk is currently limited by a lack of suitable technologies to collect long‐term data on marine mammal behaviour around tidal turbines. 2. Sonar provides a potential means of tracking marine mammals around tidal turbines. However, its effectiveness for long‐term data collection is hindered by the large data volumes and the need for manual validation of detections. Therefore, the aim here was to develop and test automated classification algorithms for marine mammals in sonar data. 3. Data on the movements of harbour seals were collected in a tidally energetic environment using a high‐frequency multibeam sonar on a custom designed seabed‐mounted platform. The study area was monitored by observers to provide visual validation of seals and other targets detected by the sonar. 4. Sixty‐five confirmed seals and 96 other targets were detected by the sonar. Movement and shape parameters associated with each target were extracted and used to develop a series of classification algorithms. Kernel support vector machines were used to classify targets (seal vs. nonseal) and cross‐validation analyses were carried out to quantify classifier efficiency. 5. The best‐fit kernel support vector machine correctly classified all the confirmed seals but misclassified a small percentage of non‐seal targets (~8%) as seals. Shape and non‐spectral movement parameters were considered to be the most important in achieving successful classification. 6. Results indicate that sonar is an effective method for detecting and tracking seals in tidal environments, and the automated classification approach developed here provides a key tool that could be applied to collecting long‐term behavioural data around anthropogenic activities such as tidal turbines.PostprintPeer reviewe

Post-disturbance haulout behaviour of harbour seals

1. The impact of anthropogenic activity associated with the construction of a proposed tidal turbine on harbour seals (Phoca vitulina) was investigated using controlled disturbance trials.2. Trials were conducted by approaching hauled out seals by boat at a speed of five knots until all seals had entered the water. Trials were carried out at a frequency of once every three days when weather permitted and the post disturbance haulout behaviours of the seals were documented. The time taken for numbers to recover to pre-disturbance levels was determined by monitoring haulout sites using time-lapse photography. In addition, seals were tagged with GPS phone tags providing haulout location and at-sea movement data allowing investigation of how disturbance may influence haulout site choice and seal distribution.3. Mean post-disturbance recovery of seals was 52% (95%CI 35-69%) within 30 minutes. However, mean recovery only returned to 94% (95%CI 55-132%) of pre-disturbance levels after four hours.4. Telemetry tagged seals displayed a high degree of haulout site fidelity. Disturbance trials did not have a significant effect on the probability of seals moving to a different haulout site. 5. The results of this study suggest that increased boat activity that causes seals to enter the water at a higher than normal frequency will not cause individuals to relocate to another haulout site. Seals continued to return to the original site despite repeated disturbance trials suggesting that increased boat activity is likely to repeatedly impact on the same seals with the largest effect being to reduce the amount of time available to seals to haul out.6. This study recommends that monitoring effort to mitigate against increased levels of disturbance caused by boat activity need only be on a local scale relative to any proposed development

Can a gray seal (Halichoerus grypus) generalize call classes?

Past researchers have found that gray seals (Halichoerus grypus) are capable of classifying vocal signals by call type using a trained set, but were unable to generalize to novel exemplars (Shapiro, Slater, & Janik, 2004). Given the importance of auditory categorization in communication, it would be surprising if the animals were unable to generalize acoustically similar calls into classes. Here, we trained a juvenile gray seal to discriminate novel calls into 2 classes, “growls” and “moans,” by vocally matching call types (i.e., the seal moaned when played a moan and growled when played a growl). Our method differed from the previous study as we trained the animal using a comparatively large set of exemplars with standardized durations, consisting of both the seal’s own calls and those of 2 other seals. The seal successfully discriminated growls and moans for both her own (94% correct choices) and the other seals’ (87% correct choices) calls. We used a generalized linear model (GLM) and found that the seal’s performance significantly improved across test sessions, and that accuracy was higher during the first presentation of a sound from her own repertoire but decreased after multiple exposures. This pattern was not found for calls from unknown seals. Factor analysis for mixed data (FAMD) identified acoustic parameters that could be used to discriminate between call types and individuals. Growls and moans differed in noise, duration and frequency parameters, whereas individuals differed only in frequency. These data suggest that the seal could have gained information about both call type and caller identity using frequency cues.PostprintPeer reviewe

Harbour seal haulout transition rates in and around the Sound of Islay

The aim of this study was to predict the changes in the number of seals hauled at the South-East Islay Skerries Special Area of Conservation (EIS SAC) in response to disturbance at other haulout sites. Telemetry data from 25 harbour seals, tagged between 2011 and 2014 at capture sites close to the Sound of Islay, were used to populate a movement model based on individual haulout transition matrices. This model generalised the matrices in order to represent population movements. Disturbance was modelled as the serial permanent closure of one of the 35 haulouts used by the tagged seals. The model excluded movement during the breeding season. The modelled response was the change in numbers hauled out at the Ardmore haulout site within in EIS SAC. The varying effect of disturbing different haulout sites reflected the complexity of the haulout network.Most disturbances had a positive effect of the number of seals at Ardmore (range: -0.5% to +21%). Haulout sites with the largest effects were within 50 km of Ardmore and there was little or no effect when the disturbed site was more than 150 km away. However the response was variable. Within 50km however, distance did not predict which disturbed haulouts affected Ardmore, as many sites within 50km had little or no effect. Thus the power to infer the effect of remote haulout disturbance by distance alone was limited, other than to say that the effect is greatest within 50 km of the haulout of interest.However, within a range of 50km, the shortest network path between the disturbed haulout site and Ardmore provided more information about which sites had an effect. Haulout sites network adjacent to Ardmore (such as Machrihanish and Eilean nan Coinein) had a larger influence. There was no significant effect when a disturbed haulout site was more than two transition jumps (connections) from Ardmore. Such network path information can be efficiently obtained in other areas with a simplified and cheaper telemetry systemThe effect of disturbance on the entire EIS SAC depended on the representativeness of the 25 tagged seals’ usage within the EIS SAC. The distribution of haulouts in the August moult survey differed from the haulout usage of the tagged seals in this study. However this may be due in part to redistribution during the breeding season. If the tagged seals were representative, the proportional effect of a disturbance to the EIS SAC would be similar. If, however, seals that used other haulout sites in the EIS SAC were part of a completely different network of haulout site then the effect reported here would be reduced.Whilst useful in this study, the model that was developed was essentially mechanistic. The limitations of this approach are reviewed and recommendations about future work on Individual Based Models are made.<br/

Risky decisions: a test of risk sensitivity in socially foraging flocks of Lonchura punctulata

Group foraging allows for individuals to exploit the food discoveries of other group members. If searching for food and searching for exploitation opportunities within a group are mutually exclusive alternatives, the decision to use one or the other is modeled as a producer-scrounger game because the value of each alternative is frequency dependent. Stochastic producer-scrounger models generally assume that producer provides a more variable and uncertain reward than does the scrounger and hence is a riskier foraging alternative. Socially foraging animals that are attempting to reduce their risk of starvation should therefore alter their use of producer and scrounger alternatives in response to changes in energy budget. We observed flocks of nutmeg mannikins (L. punctulata) foraging in an indoor aviary to determine whether their use of producer and scrounger alternatives were risk sensitive. Analyses of the foraging rewards of three flocks of seven birds confirm that producer is a riskier foraging strategy than is scrounger, although the difference in risk is rather small. We then submitted two other flocks to two different energy budgets and observed the foraging decision of four focal birds in each flock. All but one bird increased their relative use of the riskier producer strategy in the low food reserve treatment, but the overall use of producer did not differ significantly between treatments, providing evidence for a small but consistent effect. Copyright 2005.energy budget; producer-scrounger game; risk-sensitive foraging; social foraging

The significance of respiration timing in the energetics estimates of free-ranging killer whales (<i>Orcinus orca</i>)

Respiration rate has been used as an indicator of metabolic rates and associated cost-of-transport (COT) of free-ranging cetaceans, discounting potential respiration-by-respiration variation in O2 uptake. To investigate the influence of respiration timing on O2 uptake we developed a dynamic model of O2 exchange and storage. Individual respiration events were revealed from kinematic data from ten adult Norwegian herring-feeding killer whales (Orcinus orca) recorded with high-resolution tags (DTAGs). We compared fixed-O2-uptake-per-respiration models to O2 uptake per respiration estimated through a simple 'broken-stick' O2-uptake function, in which O2 uptake was assumed to be the maximum-possible O2 uptake when stores are depleted or maximum total body O2 store minus existing O2 store when stores are close to saturated. Conversely to assuming fixed O2 uptake per respiration, uptake from the broken-stick model yielded a high correlation (r2 &gt; 0.9) between O2 uptake and activity level. Moreover, we found that respiration intervals became less variable and increased at higher swimming speeds, possibly to increase O2 uptake efficiency per breath. As found in previous studies, COT decreased monotonically versus speed using the fixed-O2-uptake-per-respiration models. However, the broken-stick uptake model yielded a curvilinear COT-curve with a clear minimum at typical swimming speeds of 1.7-2.4 m s-1. Our results showed that respiration-by-respiration variation in O2 uptake is significant. And though O2 consumption measurements of COT for free-ranging cetaceans remain impractical, accounting for the influence of respiration timing on O2 uptake will lead to more consistent predictions of field metabolic rates than using respiration rate alone