Alpine Newts (Ichthyosaura alpestris) Avoid Habitats Previously Used by Parasite-Exposed Conspecifics

Many organisms avoid habitats posing risks of parasitism. Parasites are not generally conspicuous, however, which raises the question of what cues individuals use to detect parasitism risk. Here, we provide evidence in alpine newts (Ichthyosaura alpestris) that non-visual cues from parasite-exposed conspecifics inform habitat avoidance. Alpine newts breed in aquatic habitats and occasionally move among adjacent terrestrial habitat during breeding seasons. We completed experiments with newts whereby individuals had access to both habitats, and the aquatic habitats varied in prior occupancy by conspecifics with different histories of exposure to the parasitic skin fungus, Batrachochytrium dendrobatidis (Bd). Continuous filming of newt activity for 2 days provided little evidence that prior use of aquatic habitats by conspecifics, regardless of their Bd exposure history, immediately influenced newt habitat use. However, newts that encountered aquatic habitats used specifically by Bd-exposed conspecifics on day 1 spent less time aquatic on day 2, whereas other newts did not alter habitat use. Responses could have been elicited by cues generated by Bd stages on the conspecifics or, perhaps more likely, cues emitted by the conspecifics themselves. In either case, these observations suggest that newts use non-visual cues sourced from exposed conspecifics to detect Bd risk and that those cues cause newts to avoid aquatic habitats. Bd may therefore influence host behavior in early phases of interactions, and possibly before any contact with infectious stages is made, creating potential for non-consumptive effects.

Ecology of fear: environment-dependent parasite avoidance among ovipositing Drosophila

Habitat avoidance is an anti-parasite behaviour exhibited by at-risk hosts that can minimize exposure to parasites. Because environments are often heterogeneous, host decision-making with regards to habitat use may be affected by the presence of parasites and habitat quality simultaneously. In this study we examine how the ovipositing behaviour of a cactiphilic fruit fly, Drosophila nigrospiracula, is affected by the presence of an ectoparasitic mite, Macrocheles subbadius, in conjunction with other environmental factors – specifically the presence or absence of conspecific eggs and host plant tissue. We hypothesized that the trade-off between site quality and parasite avoidance should favour ovipositing at mite-free sites even if it is of inferior quality. We found that although flies avoided mites in homogeneous environments (86% of eggs at mite-free sites), site quality overwhelmed mite avoidance. Both conspecific eggs (65% of eggs at infested sites with other Drosophila eggs) and host plant tissue (78% of eggs at infested sites with cactus) overpowered mite avoidance. Our results elucidate the context-dependent decision-making of hosts in response to the presence of parasites in variable environments, and suggest how the ecology of fear and associated trade-offs may influence the relative investment in anti-parasite behaviour in susceptible hosts.

Why Marine Mammals Matter to Your Terrestrial Export Pipeline Project

Increases in export pipeline development can result in a corresponding increase in marine transportation activities and the potential to escalate adverse interactions with marine wildlife. Ship traffic introduces risks of vessel strikes as well as the amount of underwater noise produced in the marine environment. Growing public and scientific concern over the potential effects of increasing ship traffic on marine wildlife mean that even terrestrially-based pipeline projects need to start considering the effects of shipping in developing environmental mitigation programs for their export operations. Northern Gateway is proposing to construct and operate twin pipelines between Alberta and British Columbia, and an associated tank and marine terminal for export operations. While Northern Gateway will not own or operate any of the tankers, they have committed to implementing a comprehensive marine mitigation, monitoring and research program, including measures to reduce ship strikes and effects of underwater noise on marine mammals. Vessel strikes can cause severe or fatal injuries. Higher relative risk exists where shipping traffic overlaps with increased densities of marine mammals. Vessel speed has been positively correlated with the degree of risk and injury; consequently, Northern Gateway has set maximum year-round speed restrictions of 10–12 knots for all Project-related tankers calling at the marine terminal, with further restrictions of 8–10 knots in key areas. Other large vessels in this region currently travel at speeds of 16–21 knots. Mandatory speed restrictions will also reduce the Project’s contribution to underwater noise. Effects of underwater noise on marine mammals include temporary habitat avoidance, reduced feeding efficiency, behavioural change, increased stress, and communication masking. Acoustic modeling conducted for the project predicted that reducing vessel speeds from 15 to 9.6 knots would decrease underwater noise input by nearly 12 dB, making the zone of ensonification 2–3 times smaller than in the absence of mitigations. Purpose-built escort tugs will use best commercially-available noise-quieting technology and speed restriction areas will be refined through six-years of surveys and a quantitative vessel strike analysis. Vessel traffic is not unique to Northern Gateway; however, through minimizing their incremental contribution, they hope to serve as an industry example. This approach to minimizing effects of routine marine export operations is unique in the shipping industry in Canada and the United States. If other proponents were to adopt similar types of measures, Northern Gateway believes that the marine environment would see some net benefits in terms of a reduction in adverse effects on marine mammals.

Ecological Adaptation and Speciation: The Evolutionary Significance of Habitat Avoidance as a Postzygotic Reproductive Barrier to Gene Flow

Habitat choice is an important component of most models of ecologically based speciation, especially when population divergence occurs in the face of gene flow. We examine how organisms choose habitats and ask whether avoidance behavior plays an important role in habitat choice, focusing on host-specific phytophagous insects as model systems. We contend that when a component of habitat choice involves avoidance, there can be repercussions that can have consequences for enhancing the potential for specialization and postzygotic reproductive isolation and, hence, for ecological speciation. We discuss theoretical and empirical reasons for why avoidance behavior has not been fully recognized as a key element in habitat choice and ecological speciation. We present current evidence for habitat avoidance, emphasizing phytophagous insects, and new results for parasitoid wasps consistent with the avoidance hypothesis. We conclude by discussing avenues for further study, including other potential roles for avoidance behavior in speciation related to sexual selection and reinforcement.

Habitat Selection and Mating Success in a Mustelid

Habitat selection remains a poorly understood ecological process, but relating mating behaviour to pattern of habitat selection constitutes a fundamental issue both in evolutionary ecology and in biological conservation. From radiotelemetry protocol, habitat-induced variations in mating success were investigated in a solitary mustelid carnivore, the European polecatMustela putorius. Selection for marshy habitat was regarded as adaptive in that mating success was found greater using marches than other habitats. Males consorted with 1.3 females, revealing a low polygyny rate. Pregnant or lactating females selectively shifted to deciduous woods. That some habitat types may favour a good reproduction forms a key factor for species conservation and environmental management. Nevertheless, such as in various vertebrates, habitat requirements seem to be based on simple broad features of habitat, suggesting that habitat avoidance rather than habitat preference can explain polecat habitat predilection.

Reindeer and caribou (Rangifer tarandus) response towards human activities

We address the question of how human activities and infrastructure influence reindeer/caribou’s (Rangifer tarandus) behaviour and habitat use and review studies based on current methodologies. Anthropogenic activities have a direct affect on Rangifer behaviour through the senses hearing, sight and smell, and all of these are important tools for behavioural risk assessment. Short term indirect responses, such as habituation, sensitisation, avoidance, and displacement, develop through neutral, positive or negative associations towards stimulus in terms of Rangifer’s ability to experience, learn, and remember. Long term behavioural responses develop through interaction with predators and, for reindeer, also domestication. A survey of the literature dealing with behavioural studies reveals that although Rangifer in most cases retreat from anthropogenic activities, comfort distances (i.e. distances beyond which animal behaviour or activity are not influenced) are relatively short. In most cases, energetic implications appear moderate and small compared to other natural, biotic influences such as disturbance (and death) caused by insect and/or predator harassment. Unless obstructing access, physical constructions of various kinds apparently have limited effects on Rangifer behaviour or habitat use. On the other hand, constructions that do obstruct or limit access and recreational or other motorized and non-motorized activities appear to have stronger impacts on avoidance and redistribution of Rangifer. Behavioural effects that might decrease survival and reproduction include retreat from favourable habitat near disturbance sources and reduction of time spent feeding with resulting energy depletion over time. Rangifer habitat use, habitat avoidance, and feeding preferences are governed by a complexity of natural interacting factors. Domestication, habituation and sensitisation are essential in shaping Rangifer’s adaptability, and should be included in future studies on reindeer and caribou responses towards various anthropogenic activities. Although cumulative effects from human activities are likely, it remains difficult to separate these from natural variations in Rangifer habitat use and demography. Habitat avoidance towards various human infrastructures and activities is reported, but most studies reporting relatively far (4-25 km) avoidance distances relied on measurements of range properties and animal distribution recorded on 1-2 days annually in winter to induce a potential response from the animals and lack important environmental variables and/or alternative hypothesises. This methodology should be improved in order to enable identification of correlation versus causation. Studies relying on animal behaviour measurements can more correctly identify and test responses to various stimuli while also controlling for degree of domestication and other various environmental variables, but only in a limited time and spatial scale. Furthermore, such studies may not necessarily capture potential population consequences from disturbances. Thus, there are important weaknesses in the two leading methodologies (measuring animal behaviour and indirectly mapping regional/population movements and habitat use through measurements of range properties). To best study Rangifer’s responses towards anthropogenic infrastructure and activities, we propose that the two methodologies be combined and supplied with modern GPS/telemetry.Abstract in Norwegian / Sammendrag:Rein og caribous reaksjon på forskjellige menneskelige aktiviteter og installasjoner Vi adresserer spørsmålet om hvordan menneskelig aktivitet og infrastruktur påvirker rein/caribous (Rangifer tarandus) atferd og områdebruk og gjennomgår publiserte arbeider basert på aktuelle metoder. Antropogene aktiviteter har direkte effekt på reinens atferd via hørsel, syn og lukt; alle er viktige for deres risikovurdering. Kortsiktige indirekte reaksjonsmønstre, slik som habituering, sensitivisering, unnvikelse og fortrengning utvikles gjennom nøytrale, positive eller negative opplevelser av stimuli i henhold til erfaring, læring og hukommelse. Utviklingen av permanente atferdsmønstre skjer ved samvirke med predatorer og for reinens del, også ved domestisering. En litteraturoversikt om atferdsstudier viser at selv om Rangifer i de fleste tilfeller unnviker antropogene virksomheter, så er de avstander dyrene velger å ha mellom seg og infrastruktur uten at normalatferden endres, relativt korte. De energimessige implikasjonene er også beskjedne sammenlignet med virkningen av naturlige stressfaktorer så som forstyrrelser (og død) forårsaket av insekter og predatorer. Fysiske installasjoner av ulik art har også begrenset effekt med mindre de fysisk hindrer Rangifers områdebruk. På den annen side vil fysiske installasjoner, som hindrer eller begrenser bruken av områder, og trafikk, både fottrafikk og trafikk med motorkjøretøy, kunne ha sterkere virkning på unnvikelsesatferd og områdebruk. Atferdsmessige effekter som kan redusere overlevelse og reproduksjon omfatter unnvikelse fra beiteområder nær forstyrrelseskilder. For Rangifer er det negative resultatet av dette øket aktivitet, redusert beitetid og nedbygging av energireserver. Rangifers områdebruk, unnvikelsesatferd og næringspreferanser bestemmes ut fra et kompleks av naturlige og gjensidig påvirkende faktorer. Domestisering, habituering og sensitivisering som er sentrale begrep i utformningen av Rangifers tilpasningsevne, bør inkluderes i fremtidige studier av rein og caribous reaksjon på antropogene aktiviteter. Selv om en kumulativ atferdseffekt av menneskelige aktiviteter er mulig, er det vanskelig å skille slike fra naturlige variasjoner som følge av variasjoner i områdebruk og bestandsdynamiske forhold. Habitatunnvikelse som følge av menneskelig påvirkning er rapportert. De fleste studiene som rapporterer relativt lange unnvikelsesavstander (4-25 km) er imidlertid basert på målinger av beiteslitasje og lokalisering av dyr registrert i løpet av 1-2 dager årlig i løpet av vinteren og mangler viktige miljøparametere og/eller alternative hypoteser. Denne metoden bør forbedres for å kunne skille mellom korrelasjon og kausalitet. Målinger av atferd gjør mulig en mer korrekt testing av Rangifers reaksjon på ulike antropogene stimuli samtidig som man kontrollerer for graden av domestisering og forskjellige miljøfaktorer. Atferdsstudiene avgrenses imidlertid i både tid og rom og vil vanligvis ikke fange opp eventuelle bestandsdynamiske konsekvenser av forstyrrelser. Det hefter følgelig svakheter ved begge de to dominerende metodene som i dag anvendes; måling av atferd og bestandsfordeling og indirekte kartlegging av områdebruk ved måling av beiteslitasje. For å oppnå en bedre studiedesign for måling av Rangifers reaksjon på antropogen infrastruktur og tilknyttede aktiviteter foreslår vi at de to metodene kombineres og suppleres med GPS/telemetri teknologi.