Abundance estimation of wildlife populations is frequently derived from systematic survey data. Accuracy and precision of estimates, however, depend on the number of replicate surveys, and on adjustments made for animals unavailable to (availability bias), or available but undetected (perception bias) by observers. This study offers a comprehensive analysis of the relative influence of methodological, environmental and behavioral factors on availability bias estimates from photographic and visual aerial surveys of a small cetacean with a highly clumped distribution, the beluga (Delphinapterus leucas). It also estimates the effect of the number of surveys on accuracy and precision of abundance estimates, using 28 replicate visual surveys flown within a 16—29 day window depending on survey year. Availability bias was estimated using detailed dive data from 27 beluga from the St. Lawrence Estuary, Canada, and applied to systematic visual and photographic aerial surveys of this population, flown using various survey platforms. Dive and surface interval durations varied among individuals, and averaged (weighted) 176.6 s (weighted s.e. = 12.6 s) and 51.6 s (weighted s.e. = 4.5 s), respectively. Dive time and instantaneous availability, but not surface time, were affected by local turbidity, seafloor depth, whale behavior (i.e., whether beluga were likely in transit or not), and latent processes that were habitat-specific. Overall, adjustments of availability for these effects remained minor compared to effects from survey design (photographic or visual) and type of platform, and observer search patterns. For instance, mean availability varied from 0.33—0.38 among photographic surveys depending on sightings distribution across the study area, but exceeded 0.40 for all visual surveys. Availability also varied considerably depending on whether observers searched within 0-90° (0.42—0.60) or 170° (0.70—0.80). Simulation-based power analysis indicates a large benefit associated with conducting more than 1 or 2 survey reps, but a declining benefit of conducting > 5—10 survey reps. An increase in sample size from 2, to 5, and 10 reps decreased the CV from 30, to 19 and 13%, respectively, and increased the probability of the abundance estimate being within 15% of true abundance from 0.42, to 0.59 and 0.69 in species like beluga.

Aim To evaluate how the spatial distribution of a heavily exploited marine gastropod (i.e. Queen conch) varies in response to a number of known biotic and abiotic variables within and between study areas that vary in environmental conditions. Location Three study areas in the north-eastern Caribbean, Anguilla, Saba Bank and St. Eustatius. Methods A novel towed video system and complemented belt transects to estimate adult queen conch densities throughout its depth range. Bayesian hierarchical spatial models (integrated nested Laplace approximations) modelled distribution patterns of adult conch. Results Our study revealed patchy distribution patterns of adult conch caused by spatial dependency. This dependency is most likely related to aggregating behaviour during spawning events. Environmental variables, such as algal cover, distance to the open ocean and depth, showed important nonlinear effects on conch abundance, although these differed among study areas. Intermediate and deep areas (ca. 17-45 m) contain most of the reproductive output of conch in the study areas and are highly important for the reproductive capacity. Main conclusions The general patchy distribution pattern and the lack of strong generic relationships between biotic and abiotic factors and adult conch abundance and distribution are likely to be at least partly due to spatial dependency and location-specific factors, which affect different phases of the conch's life history. The depth distribution of conch also indicates that surveying areas at depths beyond the practical limitation of divers is of great importance to obtain more reliable population estimates.

In the last 50 years, traditionally nomadic indigenous communities in Amazonia have increasingly adopted more sedentary lifestyles as a result of external influences. Permanent settlements lead to the concentration of disturbances (e.g., forest extraction and hunting) and threaten vulnerable species as well as those that provide important ecosystem services such as dung beetles. Here we evaluated the abundance, taxonomic, and functional structure (composition and diversity) of an ecological indicator group—dung beetles—along a disturbance gradient associated with a permanent settlement of the Jotï people in the Amazonian region of Venezuela. We applied generalized linear model to assess the response of dung beetle abundance to settlement distance and latent variable model to assess the influence of settlement distance on taxonomic diversity and functional structure. We found the abundance of roller-species increased but small-bodied beetles decreased away from the settlement. We found that proximity to the Jotï settlement did not affect metrics of taxonomic and functional diversity of the dung beetle assemblages in general, although functional evenness was lower away from the settlement. In contrast, we found impacts on the functional composition of dung beetles, with significant increase in the community-weighted means for roller species and large-bodied dung beetles away from Jotï settlement. Our findings suggest that the transition from nomadism to a more sedentary lifestyle has not caused widespread collapse in the diversity of dung beetle assemblages surrounding the settlement, however significant trends were observed in species-specific responses to human impact, and these responses were mediated by functional traits.

Summary Scientific investigation is of value only insofar as relevant results are obtained and communicated, a task that requires organizing, evaluating, analysing and unambiguously communicating the significance of data. In this context, working with ecological data, reflecting the complexities and interactions of the natural world, can be a challenge. Recent innovations for statistical analysis of multifaceted interrelated data make obtaining more accurate and meaningful results possible, but key decisions of the analyses to use, and which components to present in a scientific paper or report, may be overwhelming. We offer a 10‐step protocol to streamline analysis of data that will enhance understanding of the data, the statistical models and the results, and optimize communication with the reader with respect to both the procedure and the outcomes. The protocol takes the investigator from study design and organization of data (formulating relevant questions, visualizing data collection, data exploration, identifying dependency), through conducting analysis (presenting, fitting and validating the model) and presenting output (numerically and visually), to extending the model via simulation. Each step includes procedures to clarify aspects of the data that affect statistical analysis, as well as guidelines for written presentation. Steps are illustrated with examples using data from the literature. Following this protocol will reduce the organization, analysis and presentation of what may be an overwhelming information avalanche into sequential and, more to the point, manageable, steps. It provides guidelines for selecting optimal statistical tools to assess data relevance and significance, for choosing aspects of the analysis to include in a published report and for clearly communicating information.

Members of the widespread arid Australian mulga (Acacia aneura) complex are fire-sensitive shrubs or small trees that can resprout epicormically following low-severity burning, but are readily killed by high-severity fire. The seeds of many species of mulga are stimulated to germinate by heat during burning, although post-fire regeneration rates are unpredictable. Here, we investigated whether variability in post-fire mulga recruitment relates to the relationship between fire severity and soil heating during fire, which may kill, leave unaffected, or stimulate the germination of buried seeds. This hypothesis was examined in central Australia on slender mulga (A. aptaneura), by experimentally investigating (a) seedling recruitment rates under different fire severity classes, (b) the germination and lethal temperature thresholds of seeds, (c) soil temperatures during fires of different severity classes and (d) the emergence depths of seedlings beneath high- and low-severity burnt plants. We found that post-fire recruitment was significantly lower beneath low-severity burnt and unburnt plants than high-severity burnt plants. This result was explained by the finding that maximum germinability of mulga seeds occurs after heating to between 80 and 100 °C, and that these temperatures are not achieved in unburnt patches or low-severity burns at depths where the majority of the seed bank is known to occur. Despite the increased regeneration observed after high-severity fire, post-fire recruitment was highly variable between sites, independent of fire severity. This indicates that while heat-stimulated germination may confer on mulga a risk-spreading strategy to a range of fire severities, post-burn recruitment may not always offset high adult death rates following high-severity fire.

Sex-biased dispersal is common in most mammals, but a female bias is less so and exceptionally rare in solitary mammals. Here we present genetic and observational evidence for strong female-biased dispersal in a solitary foraging small carnivore, the slender mongoose. We suggest that females benefit from dispersal by avoiding kin competition over local resources and inbreeding, while males can benefit from philopatry through kin cooperation leading to an increased success in female defence. The comparison between our observations and those of a previous study in Tanzania suggest that there is ecologically influenced flexibility in dispersal patterns within this species, influencing sex-specific benefits of dispersal and philopatry. Comparing our results with those on the closely related, more social mongoose species in which both sexes commonly disperse suggests that dispersal patterns are linked to a species' social system by the opportunity, or lack of it, in philopatry to obtain unrelated mating partners and gain indirect fitness benefits.

The ongoing daily sampling programme of the fish fauna in the Dutch Wadden Sea using fixed gear was analysed for the years 1960-2011. Spring sampling caught immigrating fish from the coastal zone and autumn samples reflected emigration of young-of-the-year. In total 82 fish species were caught with no clear trend in biodiversity. In both spring and autumn total daily catch fluctuated and peaked in the late 1970s. From 1980 to the present catches of both pelagic and demersal species showed a 10-fold decrease in total biomass. Mean individual biomass decreased in spring between 1980 and the present from about 150 to 20 g wet weight. No trend was found in autumn mean individual biomass which fluctuated around 20 g wet weight. The trophic structure remained constant for both the demersal and benthopelagic fish fauna from 1980 to 2011, whilst the trophic position of pelagic fish in spring fell from about 3.9 to 3.1. Min/max auto-correlation factor analysis showed similar trends in spring and autumn species biomass time series: the first axis represented a decrease from the 1960s followed by stabilization from the mid-1990s. The second trend showed an increase with a maximum around 1980 followed by a steady decrease in spring and a decrease and stabilization from 2000 in autumn. It is argued that the most likely explanatory variables are a combination of external factors: increased water temperature, habitat destruction in the coastal zone (sand dredging and beach nourishment, fishing) and increased predation by top predators for the first trend, and large-scale hydrodynamic circulation for the second trend. We conclude that both the trophic structure of the coastal zone fauna and the nursery function of the Wadden Sea have been reduced since the 1980s. Our findings corroborate that ecological change in coastal ecosystems has not only occurred in the past but still continues. (C) 2015 Elsevier Ltd. All rights reserved.

Conflicts between humans and crocodilians are a widespread conservation challenge and the number of crocodile attacks is increasing worldwide. We identified the factors that most effectively decide whether a victim is injured or killed in a crocodile attack by fitting generalized linear models to a 42-year dataset of 87 attacks (27 fatal and 60 non-fatal) by saltwater crocodiles (Crocodylus porosus) in Australia. The models showed that the most influential factors were the difference in body mass between crocodile and victim, and the position of victim in relation to the water at the time of an attack. In-water position (for diving, swimming, and wading) had a higher risk than on-water (boating) or on-land (fishing, and hunting near the water's edge) positions. In the in-water position a 75 kg person would have a relatively high probability of survival (0.81) if attacked by a 300 cm crocodile, but the probability becomes much lower (0.17) with a 400 cm crocodile. If attacked by a crocodile larger than 450 cm, the survival probability would be extremely low (<0.05) regardless of the victim's size. These results indicate that the main cause of death during a crocodile attack is drowning and larger crocodiles can drag a victim more easily into deeper water. A higher risk associated with a larger crocodile in relation to victim's size is highlighted by children's vulnerability to fatal attacks. Since the first recently recorded fatal attack involving a child in 2006, six out of nine fatal attacks (66.7%) involved children, and the average body size of crocodiles responsible for these fatal attacks was considerably smaller (384 cm, 223 kg) than that of crocodiles that killed adults (450 cm, 324 kg) during the same period (2006-2014). These results suggest that culling programs targeting larger crocodiles may not be an effective management option to improve safety for children.

In subarctic waters winter may be the period during which seabirds face the greatest environmental and physiological pressures, yet seabird distribution during this time is poorly understood. Using at-sea surveys conducted in Prince William Sound, Alaska on research 'ships of opportunity' from November 2007 to March 2009, we investigated how seabird abundance and distribution vary within and between winters for three common seabird species with extensive ranges: common murre (Uria aalge), marbled murrelet (Brachyramphus marmoratus), and black-legged kittiwake (Rissa tridactyla). Due to a large proportion of zeros in the survey data, hurdle models were performed using generalized additive mixed models. Across the two winters, consistent temporal patterns in density and distribution were observed for all species. Common murre and marbled murrelet both increased in number in midwinter, while black-legged kittiwake decreased to very low numbers. Habitat association models revealed that common murre favored relatively protected waters while marbled murrelet favored inside bays and passages (which make up 45% of semi-protected waters) and areas of higher sea surface temperatures. Our results suggest that winter storms influenced seabird distribution, particularly in midwinter when temperatures were lowest and storms more frequent. This influence was greater than variables providing proxies for foraging opportunities, which were absent from selected models. Our study highlights the importance of considering species-specific temporal patterns throughout the non-breeding season to guide marine spatial planning that will fully address seabird conservation issues.

Acknowledgements The authors are indebted to CONACYT (Mexican National Council for Science and Technology) and staff of the Marine Scotland Science, Marine laboratory, Aberdeen

Using a unique 50-year high-resolution time series of daily kom-fyke catches, long-term patterns of scyphomedusae in the western Dutch Wadden Sea were analysed and related to changes in environmental conditions [eutrophication in the 1980s–1990s and recent climate change (increased water temperature)] in the area. Over the years, species composition and general pattern of appearance has remained the same: the first species that occurred in spring was Aurelia aurita, followed by Cyanea lamarckii/C. capillata. Chrysaora hysoscella and Rhizostoma octopus occurred from June to July onwards. All species appeared earlier in recent decades and first appearance and peak occurrence of A. aurita was in part inversely related to previous winter seawater temperature. Last occurrence of C. hysoscella was related to summer seawater temperature and the species is present longer in recent decades. Phenological relationships might have been decoupled since the seasonality of the phytoplankton bloom did not change. All species showed large inter-annual abundance fluctuations, with prolific years followed by sparse years. Peak catches of the coastal species A. aurita occurred in the late 1970s-early 1990s when eutrophication peaked, however, without a significant relationship with total nitrogen input into the area. Unlike for phenology, the patterns of mean abundance of any species did not show a relationship to climate change in the area. This might imply that population regulating mechanisms do not operate during the planktonic phase but during the sessile demersal polyp stages

Mast seeding, the intermittent production of large synchronised seed crops among plant populations, is a phenomenon that occurs at exceptionally long intervals in spinifex grasses (Triodia spp.) from arid regions of Australia. This is despite the reliance of these fire-sensitive plants on seeds for post-fire regeneration, and that spinifex grasslands rate among Australia’s most flammable ecosystems. The proximate causes and possible adaptive functions of masting in seven species of spinifex from arid regions within the 350-mm rainfall isohyet were investigated. Specifically, the seed set percentages of 79 specimens collected between 1947 and 2012 were related to the following environmental covariates: antecedent rainfall over 6, 12 and 36 months, relative humidity, and the number of days above 40°C and below 0°C during anthesis. Given the potential importance of seeding events for post-fire regeneration, it was also investigated whether masting in Triodia could represent a fire-related form of environmentally predictive masting, by testing whether high-yield years corresponded to years of increased fire occurrence. Examination of the dataset showed that 43% of specimens contained completely aborted inflorescences (0% seed fill), while seed set ranged from 2 to 69% in the remaining specimens. High levels of insect activity were also found, with 42% of specimens showing evidence of insect occupation. Statistical analyses showed that the main environmental driver of seed set was high precipitation over the previous 12 months, and that high-yield years were strongly related to years of increased fire likelihood. The number of days over 40°C was a weakly significant driver of yield, while the remaining covariates were not significant. It is hypothesised that intermittent reproduction by Triodia is a fire-related form of environmentally predictive masting, which maximises chances of post-fire regeneration by satiating seed predators during flammable periods (i.e. after heavy rain years). Furthermore, it is suggested that non-viable flower crops after initial low rainfalls may have an adaptive function, by diluting pre-dispersal seed predator densities with ‘decoy’ ovules that do not mature and lead to the starvation of developing larvae.

Members of the arid Australian mulga (Acacia aneura) complex are fire-sensitive shrubs that produce mast seed crops after exceptionally high rainfall years. Such years also drive widespread wildfires in inland Australia, as high rainfall causes grassy fuels to accumulate, thereby enabling fuel contiguity to occur. Despite seedling regeneration playing an important role in mulga post-fire recovery, a dearth of information exists on the dynamics of its seedbanks. Here we examine the temporal and spatial dynamics of mulga seedbanks after a region-wide masting event at Laycock's Sandplain, central Australia. Masting had a profound effect on seedbanks, producing massive but short-lived pulses of seed in upper soil layers. After seed fall, seedbanks declined rapidly, and within 18 months had been reduced by predator depredations to low pre-mast levels. Our results suggest that mulga masting should enhance resilience to burning by providing transient seed pulses during periods of high flammability (i.e. after heavy rainfalls). The results also suggest that burn intensity will influence post-fire regeneration, by interacting with seed germination biology and post-mast seedbank dynamics. In our discussion, we examine possible evolutionary drivers behind mulga seeding periodicity, and hypothesize that rain-driven masting in mulga is a fire-related form of environmentally predictive masting.

This article shows how to apply generalized additive models and generalized additive mixed models to single-case design data. These models excel at detecting the functional form between two variables (often called trend), that is, whether trend exists, and if it does, what its shape is (e.g., linear and nonlinear). In many respects, however, these models are also an ideal vehicle for analyzing single-case designs because they can consider level, trend, variability, overlap, immediacy of effect, and phase consistency that single-case design researchers examine when interpreting a functional relation. We show how these models can be implemented in a wide variety of ways to test whether treatment is effective, whether cases differ from each other, whether treatment effects vary over cases, and whether trend varies over cases. We illustrate diagnostic statistics and graphs, and we discuss overdispersion of data in detail, with examples of quasibinomial models for overdispersed data, including how to compute dispersion and quasi-AIC fit indices in generalized additive models. We show how generalized additive mixed models can be used to estimate autoregressive models and random effects and discuss the limitations of the mixed models compared to generalized additive models. We provide extensive annotated syntax for doing all these analyses in the free computer program R.

Environmental conditions during the larval phase (food concentration and temperature) impact recruitment success of marine bivalves by affecting growth and survival. We analysed the seasonal match between environmental conditions and larval presence of six coastal bivalve species over eight consecutive years (2006-2013) in the western Wadden Sea, taking species-specific physiological responses to these conditions into account. The larval occurrence of four species overlapped with their optimum in environmental conditions as calculated following the Dynamic Energy Budget theory: the occurrence of larvae of Cerastoderma edule, Mya arenaria and Mytilus edulis matched with their optimum food conditions, while larvae of Crassostrea gigas were mainly found during the temperature optimum of this species. Larvae of Ensis directus and Macoma balthica, however, only occurred months after their most favourable food conditions. The first group probably uses the energy immediately after uptake for the production and release of gametes ('income breeders'), whereas the second group accumulates and stores energy reserves for later reproduction ('capital breeders'). Larvae of C. gigas and M. balthica were observed much earlier in the year than expected from previous occurrences and from formerly know threshold temperatures for spawning. These apparent changes in timing of spawning suggest that Pacific oysters and Baltic tellins have recently acclimated to new environmental conditions.