GPS tracking reveals rafting behaviour of Northern Gannets (Morus bassanus): implications for foraging ecology and conservation

Capsule Three quarters of tracked Northern Gannets (Morus bassanus) at Grassholm gathered in rafts around the colony, concentrated within a recently designated at-sea Special Protection Area (SPA), but rafting was not correlated with foraging effort.

Aims To investigate the incidence, distribution and foraging implications of Northern Gannet rafting behaviour in waters adjacent to a large colony.

Methods Using bird-borne global positioning system (GPS) loggers we reconstructed at-sea movement and used a speed filter to identify rafting behaviour within 10?km of the colony. We mapped the spatial distribution of rafting events from 160 breeding individuals over 5 years, and investigated the relationship between foraging effort (trip duration and total distance travelled) and the presence/absence of rafting.

Results On average, 74% of tracked birds engaged in rafting. Of the 381 foraging trips analysed, rafting was recorded on 237 (62%). Birds were more likely to raft on outbound (224 trips, 59%), than inbound journeys (38 trips, 10%). Presence/absence of rafting did not correlate significantly with foraging trip distance or duration nor with duration of nest attendance. The majority of rafting was concentrated in a 2-km radius around the colony within a recently designated seaward SPA extension. Birds showed low individual repeatability in rafting, although there was lower variation within, than among, individuals.

Conclusion Our results show that rafting is important for breeding gannets on Grassholm, and a recently designated at-sea SPA encapsulates the core distribution of rafting. Rafting did not appear to be correlated with foraging behaviour. Given the dearth of literature on rafting and the wealth of GPS tracking data for seabirds, we suggest that similar research be conducted elsewhere to further elucidate the ecological and applied significance of this behaviour.     

Weather effect on widely distributed seabirds through migration flyways: a case study with the Northern Gannet Morus bassanus in the Bay of Biscay

Capsule: Northern Gannet Morus bassanus counts obtained from a coastal monitoring network in northern Spain were highly determined by wind conditions.

Aims: To determine how external factors including weather conditions affect seabird counts in a land-based seabird monitoring project (Red de observación de Aves y Mamíferos marinos, RAM project; Seabird & Marine Mammal Observation Network).

Methods: Seabird counts were obtained from four study capes situated in the southeastern part of the Bay of Biscay in northern Spain. Counts were conducted on a monthly-basis for a period of 3 hours starting at dawn on each sampling day. Data used here were compiled over a 10-year period (2006–15).

Results: Northern Gannet numbers were chiefly influenced by meteorological conditions at a local spatial scale. Northwesterly winds were found to positively influence gannet abundance, whereas high relative humidity caused a decrease in abundance. Moreover, gannets were more abundant during the non-breeding period as compared to breeding period.

Conclusion: We recommend considering the effect of the wind and relative humidity on land-based seabird counts in the Bay of Biscay when handling data from the RAM protocol in order to avoid biases and misinterpretation of data. Since seabirds approach the coast during harsh weather conditions, the RAM protocol should be improved in order to better account for the distance at which the birds are seen.     

Underwater wingbeats extend depth and duration of plunge dives in northern gannets Morus bassanus

Plunge-diving is a specialised hunting tactic used by some avian predators to overcome the high buoyancy encountered near the water surface and surprise prey. However, plunge-diving is effective only to a certain depth; to access deeper prey, birds need to use an additional method of propulsion, e.g. wings or feet. We used miniature accelerometers to record the details of the aerial and underwater phases of plunge dives by northern gannets Morus bassanus . Birds never reached depths >11  m using the momentum of the aerial part of the plunge dive and had to flap their wings underwater to gain additional depth. A biomechanical model demonstrates that little additional depth can be obtained from momentum alone when initiating a plunge from heights >40  m. Thus, the additional energy required to attain greater starting heights is not rewarded by reaching significantly greater depths. However, by using their wings underwater, gannets were able to more than double the depth attained (up to 24  m). It appears that prey may be captured by surprise in the first 10  m of the water column, whereas wing-propelled pursuit is required to catch prey at deeper depths, a strategy likely to be used only for prey of sufficient profitability to justify the cost of flapping the gannet's large wings underwater. Our study demonstrates the importance of understanding the constraints placed on predators by the physical environment when interpreting predator-prey interactions.     

The empirical coverage of confidence intervals: Point estimates and confidence intervals for confidence levels

Many confidence intervals calculated in practice are potentially not exact, either because the requirements for the interval estimator to be exact are known to be violated, or because the (exact) distribution of the data is unknown. If a confidence interval is approximate, the crucial question is how well its true coverage probability approximates its intended coverage probability. In this paper we propose to use the bootstrap to calculate an empirical estimate for the (true) coverage probability of a confidence interval. In the first instance, the empirical coverage can be used to assess whether a given type of confidence interval is adequate for the data at hand. More generally, when planning the statistical analysis of future trials based on existing data pools, the empirical coverage can be used to study the coverage properties of confidence intervals as a function of type of data, sample size, and analysis scale, and thus inform the statistical analysis plan for the future trial. In this sense, the paper proposes an alternative to the problematic pretest of the data for normality, followed by selection of the analysis method based on the results of the pretest. We apply the methodology to a data pool of bioequivalence studies, and in the selection of covariance patterns for repeated measures data.     

Population dynamics of Northern Gannets in North America, 1984–2009

Northern Gannet (Morus bassanus) colonies (N = 6) in North America have been regularly censused since the late‐1960s. Monitoring populations of a top‐predator like gannets provides insight into possible changes in the marine environment and contributes to an understanding of their demography. We report the results of aerial censuses of gannet colonies conducted from 1984 to 2009. Standard methods were used and involved making high‐quality photographs of colonies from a fixed‐wing aircraft, and subsequently counting apparently occupied sites (AOS) in the photographs. As of 2009, the breeding population of gannets in North America was estimated to be 116 825 pairs, or ～27% of the world population. From 1984 to 2009, the population grew at an average rate of 4.4% per annum and this growth was likely the result of continued population recovery after acute persecution in the past. Growth rates began to slow during the latter part of our study, likely due to density‐dependent effects and reductions in food availability. Despite the growth of the North American gannet population, gannets have not established new colonies, possibly because populations had been so depressed that growth could be accommodated within existing colonies.     

Biased but in doubt: conflict and decision confidence

Human reasoning is often biased by intuitive heuristics. A central question is whether the bias results from a failure to detect that the intuitions conflict with traditional normative considerations or from a failure to discard the tempting intuitions. The present study addressed this unresolved debate by using people's decision confidence as a nonverbal index of conflict detection. Participants were asked to indicate how confident they were after solving classic base-rate (Experiment 1) and conjunction fallacy (Experiment 2) problems in which a cued intuitive response could be inconsistent or consistent with the traditional correct response. Results indicated that reasoners showed a clear confidence decrease when they gave an intuitive response that conflicted with the normative response. Contrary to popular belief, this establishes that people seem to acknowledge that their intuitive answers are not fully warranted. Experiment 3 established that younger reasoners did not yet show the confidence decrease, which points to the role of improved bias awareness in our reasoning development. Implications for the long standing debate on human rationality are discussed.     

delrious: a computer program designed to analyse molecular marker data and calculate delta and relatedness estimates with confidence

The computer program delrious analyses molecular marker data and calculates delta and relatedness estimates. A computer simulation is presented in which delrious is used to determine relations between relatedness estimate confidence and locus number. The results obtained suggest that many kinship studies probably have been conducted at significance levels less than 95%. Confidence measures provide a means of assessing reliability of calculated parameters and, therefore, would be beneficial to kinship hypothesis testing. Consequently, resampling procedures should be conducted routinely to determine delta and relatedness estimate confidence. delrious can implement bootstrap and jackknife resampling procedures for this purpose.     

Uncertainty in population growth rates: determining confidence intervals from point estimates of parameters

Background

Demographic models are widely used in conservation and management, and their parameterisation often relies on data collected for other purposes. When underlying data lack clear indications of associated uncertainty, modellers often fail to account for that uncertainty in model outputs, such as estimates of population growth.

Methodology/Principal Findings

We applied a likelihood approach to infer uncertainty retrospectively from point estimates of vital rates. Combining this with resampling techniques and projection modelling, we show that confidence intervals for population growth estimates are easy to derive. We used similar techniques to examine the effects of sample size on uncertainty. Our approach is illustrated using data on the red fox, Vulpes vulpes, a predator of ecological and cultural importance, and the most widespread extant terrestrial mammal. We show that uncertainty surrounding estimated population growth rates can be high, even for relatively well-studied populations. Halving that uncertainty typically requires a quadrupling of sampling effort.

Conclusions/Significance

Our results compel caution when comparing demographic trends between populations without accounting for uncertainty. Our methods will be widely applicable to demographic studies of many species.     

Survival of Adult Martens in Northern Wisconsin

Abstract: Low adult marten (Martes americana) survival may be one factor limiting their population growth >30 yr after their reintroduction in Wisconsin, USA. We estimated annual adult marten survival at 0.81 in northern Wisconsin, with lower survival during winter (0.87) than summer-fall (1.00). Fisher (Martes pennanti) and raptor kills were infrequent, and each reduced marten adult annual survival <10%. Annual adult survival was similar to or higher than survival in other areas, suggesting that it was not unusually low and therefore did not limit recovery of marten populations in northern Wisconsin. We captured few juvenile martens, suggesting low reproduction or reduced juvenile survival.     

大数据在生态环境领域的应用进展与展望

随着互联网和移动通讯技术的发展,生态环境领域从信息采集到加工处理也进入信息化和数字化时代,数据量呈现爆发式增长,生态环境大数据受到越来越多的关注.生态环境大数据是在对生态环境要素“空天地一体化”连续观测的基础上,集成海量的多源多尺度信息,借助云计算、人工智能及模型模拟等大数据分析技术,实现生态环境大数据的集成分析和信息挖掘.生态环境大数据存在数据来源多样、涉及部门广;数据采集方式不统一;服务对象众多、对专业化服务要求高等特点.大数据已在生态环境领域得到了初步应用,如在全球气候变化预测、生态网络观测与模拟和区域大气污染治理等方面作用明显.目前我国生态环境大数据的发展还存在诸多问题,包括数据共享难、监测技术落后、传感器等监测设备严重依赖进口、数据集成和深度分析能力不足等.随着大数据技术的进步,未来大数据在解决生态环境健康问题、提高重大生态环境风险预警预报水平、提高生态环境领域科学研究水平等方面都将发挥巨大作用.大数据将最终实现生态环境管理决策定量化、精细化,生态环境信息服务多样化、专业化和智能化,为中国社会经济可持续发展和生态文明建设提供技术保障.     

Simultaneous confidence corridors for mean functions in functional data analysis of imaging data

Motivated by recent work involving the analysis of biomedical imaging data, we present a novel procedure for constructing simultaneous confidence corridors for the mean of imaging data. We propose to use flexible bivariate splines over triangulations to handle an irregular domain of the images that is common in brain imaging studies and in other biomedical imaging applications. The proposed spline estimators of the mean functions are shown to be consistent and asymptotically normal under some regularity conditions. We also provide a computationally efficient estimator of the covariance function and derive its uniform consistency. The procedure is also extended to the two-sample case in which we focus on comparing the mean functions from two populations of imaging data. Through Monte Carlo simulation studies, we examine the finite sample performance of the proposed method. Finally, the proposed method is applied to analyze brain positron emission tomography data in two different studies. One data set used in preparation of this article was obtained from the Alzheimer's Disease Neuroimaging Initiative (ADNI) database.     

Vegetation science in the age of big data

The age of big data is poised to revolutionize vegetation science. As online resources continue to grow, vegetation ecologists will need a growing set of computational skills to advance vegetation science in the digital age. Two papers in this issue of the Journal of Vegetation Science (Wiser 2016, Sandel et al. 2016) illustrate the resources available and use of big data to explore challenging ecological questions.     

昆虫肠道的宏基因组学:微生物大数据的新疆界

微生物作为自然界中普遍存在的生命体,通常以"微生物群落"的形式共存。这些物种相互协作适应环境变化的同时,也对环境产生了长期而深刻的影响。随着人类对于微生物了解的深入,微生物群落基础研究及其在健康和环境等领域的应用研究日益重要。昆虫肠道内存在种类繁多、数量庞大的微生物,一方面,这些肠道微生物种群结构的多样性与昆虫种类、龄期、消化道形式、食物的来源、环境等都息息相关。另一方面,这些菌群也对宿主的一些生理活动有着一定的影响。随着高通量测序技术、组学技术的发展,昆虫肠道宏基因组大数据挖掘和应用已经成为研究热点,极大地推动人类微生物资源利用的能力。本文概述了昆虫肠道微生物宏基因组学的发展现状和发展趋势,特别是肠道宏基因组学大数据的挖掘工具和应用,以及现阶段昆虫肠道宏基因组学的研究进展、应用、优势和瓶颈,并对今后昆虫肠道微生物组大数据研究方向进行展望。     

Revision of Bursacetabulus (Diplostomidae: Diplostominae) with the proposal of Bursatintinnabulus n. gen., and description of Bursatintinnabus bassanus n. sp. and Bursacetabulus morus n. sp. from northern gannet, Morus bassanus (Aves), from the Texas gulf coast.

During a study of digeneans of shorebirds from the Texas gulf coast, 2 undescribed species of diplostomes were found in northern gannet, Morus bassanus. Bursatintinnabulus n. gen. (Diplostomidae) is established with reassignment of Bursacetabulus macrobursus Dronen et al., 1999, as type species, and the second species in the proposed genus is described, Bursatintinnabulus bassanus n. sp. Generic diagnosis of Bursacetabulus Dronen et al., 1999, is emended to include a conical hindbody, an inconspicuous pouchlike or conspicuous well-developed tribocytic organ, and digitiform vitellaria distributed mainly in the hindbody with processes extending into the tribocytic organ and ventrolaterally in the hindbody to the level of the testes. Bursacetabulus morus n. sp. is described as the second species in that genus. In Diplostominae, Bursacetabulus and Bursatintinnabulus n. gen. are most similar to Tylodelphys Diesing 1850, but can be distinguished by having smooth testes and vitellaria that extend ventrolaterally into the hindbody to the level of the posterior testis; and the absence of a genital cone, an acetabulum, and a prepharynx. Bursatintinnabulus n. gen. is different from Bursacetabulus and all other genera of Diplostominae by a well-developed, bell-like skirt surrounding the bursa.