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Lagged influence of North Atlantic Oscillation on population dynamics of a Mediterranean terrestrial salamander
Abstract
The North Atlantic Oscillation (NAO) is a large-scale climatic pattern that strongly influences the atmospheric circulation in the northern Hemisphere and by consequence the long-term variability of marine and terrestrial ecosystem over great part of northern Europe and western Mediterranean. In the Mediterranean, the effects of the NAO on vertebrates has been studied mainly on bird populations but was rarely analysed in ectothermic animals, and in particular in amphibians. In this study, we investigated the relationships between winter, spring and summer NAO indexes and the long-term population dynamics of the plethodontid salamander Speleomantes strinatii. This terrestrial salamander was monitored inside an artificial cave in NW Italy for 24 consecutive years. The relationships between seasonal NAO indexes and the salamander dynamics were assessed by cross-correlation function (CCF) analysis, after prewhitening the time series by autoregressive moving average statistical modelling. Results of CCF analyses indicated that the salamander abundance varied in relation to the one-year ahead winter NAO (P = 0.018), while no relationships were found with spring and summer indexes. These results strengthen some previous findings that suggested a high sensitivity of temperate terrestrial amphibians to wintertime climatic conditions.
... Concerning long-term climate effects on subterranean salamander populations, data are limited because, apart from one study relating the population dynamics of a cave salamander to the North Atlantic Oscillation index (Salvidio et al. 2016), research has concentrated mainly on fossorial species that usually spend only part of their biological cycle in subterranean superficial habitats. Regardless, evidence of direct influence of long-term climate variations on demography and ecology of fossorial salamanders is controversial because different studies recorded different outcomes in different species. ...
... Our aim was to assess whether the salamander population dynamics were in some way showing a significant change over the study period, or whether the underground environment was efficiently buffering the effects of the local external climate. This salamander population has been monitored continuously since 1990 by using a relative index of activity and since 1996 by estimating its total abundance and demographic structure (Salvidio et al. 1994(Salvidio et al. , 2016(Salvidio et al. , 2020. ...
... This ARMA (2,1) model indicates that a second-order density dependence negative feedback together with a lagged autocorrelated external shock was driving the long-term cave population salamander dynamics. These results show agreement with those obtained in previous studies on the same population that were based on shorted time series and on counts indexes not corrected for detection probabilities (Salvidio 2009;Salvidio et al. 2016). ...
Long-term effects of current climate on animal populations living in subterranean habitats are still poorly understood. In this study, we analyzed the variability of the demographic structure and abundance of a population of terrestrial plethodontid Strinati's Cave Salamanders (Speleomantes strinatii) (Aellen, 1958) living inside a northwestern Italian artificial cave over 27 yr from 1996 to 2022. The study site is situated in the Northern Apennines, where average air temperatures measured at two local weather stations were steadily increasing, whereas precipitation was relatively constant over the past 60 yr. Our objective was to evaluate whether the demographic traits of the population of Strinati's Cave Salamanders were showing detectable signs of directional shift during the 27 yr. Each year in July, the population abundance was estimated by a three-occasion removal experiment, salamanders' snout-vent length (SVL) was measured, and the population polymodal body-size distribution was decomposed into estimated age classes. The annual population abundance, adult sex ratio, recruitment, SVL, and growth increments of first-and second-year immature salamanders were analyzed. The Strinati's Cave Salamander time series was modeled by autoregressive moving average (ARMA) analysis, and demographic parameters were tested for temporal trends. There were no directional trends observed in any of the demographic parameters of the focal cave salamander population over the study period. The best autoregressive model describing the population variation was an ARMA (2,1). Results indicated that the salamander population had a complex fluctuating pattern in which the interaction of lagged density dependence and an external autocorrelated factor were influencing the population long-term dynamics. Our findings suggest that the population of this long-lived salamander species was probably buffered from external conditions by the thermal inertia of its subterranean habitat that is known to delay and reduce the amplitude of aboveground climatic signals.
... Concerning long-term climate effects on subterranean salamander populations, data are limited because, apart from one study relating the population dynamics of a cave salamander to the North Atlantic Oscillation index (Salvidio et al. 2016), research has concentrated mainly on fossorial species that usually spend only part of their biological cycle in subterranean superficial habitats. Regardless, evidence of direct influence of long-term climate variations on demography and ecology of fossorial salamanders is controversial because different studies recorded different outcomes in different species. ...
... Our aim was to assess whether the salamander population dynamics were in some way showing a significant change over the study period, or whether the underground environment was efficiently buffering the effects of the local external climate. This salamander population has been monitored continuously since 1990 by using a relative index of activity and since 1996 by estimating its total abundance and demographic structure (Salvidio et al. 1994(Salvidio et al. , 2016(Salvidio et al. , 2020. ...
... This ARMA (2,1) model indicates that a second-order density dependence negative feedback together with a lagged autocorrelated external shock was driving the long-term cave population salamander dynamics. These results show agreement with those obtained in previous studies on the same population that were based on shorted time series and on counts indexes not corrected for detection probabilities (Salvidio 2009;Salvidio et al. 2016). ...
... This salamander is considered "endangered" by the IUCN and with a decreasing population trend (IUCN SSC Amphibian Specialist Group, 2022). However, actual trends are only available for very few populations (Salvidio et al., 2020;Salvidio et al., 2016) and quantitative broad-scale estimates are lacking. As a consequence, there is disagreement on the actual conservation status of this species between organizations (IUCN SSC Amphibian Specialist Group, 2022; Rondinini et al., 2022). ...
... The Strinati's cave salamander, Speleomantes strinatii, is endemic to this region; this species generally lives in caves, in near-surface underground environments, but, under suitable weather conditions (cold, rain), it can also be active outdoors, particularly for feeding (Lanza et al., 2006;Rosa et al., 2023). Nevertheless, caves are the site where this species is most easily detected and monitored, particularly from late spring to early autumn (Ficetola et al., 2012;Salvidio et al., 2016). ...
... Our dataset could be integrated with additional data covering the whole range, with information on populations that do not exploit caves (e.g. populations exploiting the soil of forests) and, ideally, with assessments of local abundances (Ficetola et al., 2020;Renet et al., 2012;Rosa et al., 2023;Salvidio et al., 2016) to provide a robust baseline for prompt detection of local declines in the future, and can be used as reference to understand the fate of cave salamanders under emerging threats such as infectious diseases or climate change (Dondero et al., 2023;Falaschi et al., 2019). ...
Documenting population trends is pivotal to identify the underlying drivers of biodiversity changes and setting conservation priorities. Ascertaining trends often requires long-term, standardized, monitoring data that are not always available. Historical data provide important information on past species distribution, but their integration with recent data to obtain trend estimates is challenging. Here we show how site occupancy-detection models (SODMs) can allow combining data from recent monitoring with historical ones from the gray literature. Using data on the endangered cave salamander, Speleomantes strinatii, we tested whether SODMs can provide reliable trend estimates if i) historical data include repeated within-season surveys enabling the estimation of past detectability, or if ii) information on detection/non-detection is not available. We conducted repeated surveys across 40 caves covering the species range, for which historical (1940-1982) biospeleological data were available. We then developed Bayesian SODMs i) estimating species detectability from both recent and past surveys, and then assessing trends; ii) in absence of estimates of past detectability, assessing trends by comparing scenarios on the potential misdetection rate during historical surveys. Salamanders were widespread in the study sites. SODM estimated high detectability for both recent and historical surveys and suggested a growing occupancy. Changes in occupancy were unrelated to landscape modifications. Even without historical detection/non-detection data, realistic scenarios of past misdetection consistently suggested an increasing or stable trend. The application of tailored analytical approaches is fundamental to exploit the vault of information available in historical data, and can be linked to adaptive management to promote efficient conservation actions.
... In Europe, it has been shown that warmer temperatures before the breeding period could reduce adult survival and fecundity, or lower recruitment, because of an increased consumption of nutrient reserves during overwintering (Bufo bufo: Reading 2007; Triturus cristatus : Griffiths et al. 2010;Bombina variegata: Cayuela et al. 2017). Conversely, mild winters could enhance the recruitment probability of newly-metamorphosed amphibians, because these climatic conditions are associated with increased food availability and faster growth (Speleomantes strinatii: Salvidio et al. 2016;Triturus cristatus: Cayuela et al. 2017). In parallel, pre-reproductive rainfall has been related to increased survival or breeding probability for Bombina variegata (Cayuela et al. 2014), and to enhanced colonization rates (and lowered extinction rates) at breeding ponds for several species (Cayuela et al. 2012). ...
... We detected significant effects of climatic conditions on eggclutch abundance during the autumn-winter period for which the three climatic variables analyzed (precipitation, minimum and maximum temperature) positively influenced egg-clutch abundances. Other studies have demonstrated the positive impact of autumn-winter rainfall on egg-clutches (Jensen et al. 2003;Hartel 2008) or adult (Salvidio et al. 2016) abundances, frogs' fecundity and survival (Cayuela et al. 2014;Benard 2015), or colonization rate of ponds for breeding (Cayuela et al. 2012). It is well admitted that high level of humidity would decrease desiccation risks during overwintering and migration, and would also positively influence mobility for the breeding migration (Chan-McLeod 2003;Rittenhouse et al. 2008;Köhler et al. 2011). ...
... Although some studies, as the present study, found evidence for positive autumn-winter temperature effect on eggclutch abundance (Amburgey et al. 2017) or adult abundance (Salvidio et al. 2016), others showed opposite results (Reading 2007;Griffiths et al. 2010;Benard 2015). Several studies in temperate environment have emphasized that elevated temperature during winter would increase the pattern of energy use (metabolic rates, Dillon et al. 2010) of adult females, thereby negatively influencing their survival and breeding probability (Reading and Clarke 1995;Reading 2007;Griffiths et al. 2010;Benard 2015). ...
Severe population declines of amphibians have been shown to be attributed to climate change. Nevertheless, the various mechanisms through which climate can influence population dynamics of amphibians remain to be assessed, notably to disentangle the relative synergetic or antagonistic influences of temperature and precipitations on specific life history stages. We investigated the impact of rainfall and temperature on the egg-clutch abundance in a population of agile frog (Rana dalmatina) during 29 years (1987–2016) on 14 breeding sites located in Brenne Natural Park, France. Specifically, we examined the influence of environmental conditions occurring during five temporal windows of the year cycle corresponding to specific life history stages. Overall, our results suggest that the year-to-year fluctuations of egg-clutch abundances in Brenne Natural Park were partly dependent on local climatic conditions (rainfall and temperature). Climate seemed to influence breeding frogs during the autumn-winter period preceding reproduction. Spring and summer conditions did not influence reproduction. Additionally, we failed to detect effects of climatic conditions on newly metamorphosed individuals. Other factors such as density dependence and inter-specific interactions with introduced predators are likely to play a significant role in reproduction dynamics of the studied frog populations.
... It is well known that salamander populations can undergo strong temporal variation, for instance in response to habitat modifications, climatic variation and variation of biotic factors (e.g. 7,39,40 ), and population fluctuations can occur even in absence of evident habitat changes 41 . Despite we do not have quantitative data on population dynamics, the available information suggests that the study populations did not undergo strong variations of abundance through time. ...
... High detection probability has already been demonstrated in other species of cave salamanders, particularly during their underground activity phase 5,[47][48][49] , and this favors studies on the ecology and dynamics of cave salamander populations (e.g. 39,48,49 ). The match between mixture models and removal sampling was excellent for the caves with fewer salamanders. ...
Accurate measures of species abundance are essential to identify conservation strategies. N-mixture models are increasingly used to estimate abundance on the basis of species counts. In this study we tested whether abundance estimates obtained using N-mixture models provide consistent results with more traditional approaches requiring capture (capture-mark recapture and removal sampling). We focused on endemic, threatened species of amphibians and reptiles in Italy, for which accurate abundance data are needed for conservation assessments: the Lanza's Alpine salamander Salamandra lanzai, the Ambrosi's cave salamander Hydromantes ambrosii and the Aeolian wall lizard Podarcis raffonei. In visual counts, detection probability was variable among species, ranging between 0.14 (Alpine salamanders) and 0.60 (cave salamanders). For all the species, abundance estimates obtained using N-mixture models showed limited differences with the ones obtained through capture-mark-recapture or removal sampling. The match was particularly accurate for cave salamanders in sites with limited abundance and for lizards, nevertheless non-incorporating heterogeneity of detection probability increased bias. N-mixture models provide reliable abundance estimates that are comparable with the ones of more traditional approaches, and offer additional advantages such as a smaller sampling effort and no need of manipulating individuals, which in turn reduces the risk of harming animals and spreading diseases.
... Consequently, the NAO can influence ecological processes through changes in local weather conditions (Hallet et al., 2004). It has been demonstrated that shifts between the NAO phases induce effects on the distribution, abundance, and reproduction of many vegetal and animal species, both terrestrial (OrlandiW et al., 2010;Salvidio et al., 2016) and aquatic (Melero-Jiménez et al., 2017;Muñoz-Expósito et al., 2017). In this context, bird communities are especially susceptible to changes in the NAO position due to the high dependence of many of their relevant biological processes, such as migration and breeding, on local weather conditions (Burger, 1974;Faaborg, 1976;Nudds, 1982;Moss & Moss, 1993;Battisti et al., 2006;Saunders et al.,2021). ...
Predicting how waterbird populations may respond to climate change is a major challenge for conservation, which could be addressed by understanding the effects of large-scale climate oscillations, such as the North Atlantic Oscillation (NAO), on breeding population size. Here, we explore the relationship between the NAO position and the abundance of waterbird breeding pairs in a protected Mediterranean coastal wetland (Mouth of the Guadalhorce River, Málaga, southern Iberian Peninsula). We found a significant and negative relationship between the winter NAO index and the abundance of grebes (r=-0.72, N=15, p<0.01), rails (r=-0.74, N=15, p<0.01), diving ducks (r=-0.56, N=15, p<0.05) and dabbling ducks (r=-0.54, N=15, p<0.05). Our results suggest that this relation is mediated by the NAO indirect effects on wetland flooded surface via changes in winter precipitation and Mediterranean sea level. These results should be considered to design appropriate environmental management strategies devoted to preventing or mitigating potential deleterious effects of the NAO variability on Mediterranean wetlands ecosystems and preserving their valuable waterbird communities.
... Four salamander species in the USA (Warren & Bradford 2010) showed a significant association with NAO + and one plethodontid salamander in Italy (Salvidio et al., 2016) had significant association with NAO − (Table 2). ...
Climate is a major extrinsic factor affecting the population dynamics of many organisms. The Broad-Scale Climate Hypothesis (BSCH) was proposed by Elton to explain the large-scale synchronous population cycles of animals, but the extent of support and whether it differs among taxa and geographical regions is unclear. We reviewed publications examining the relationship between the population dynamics of multiple taxa worldwide and the two most commonly used broad-scale climate indices, El Niño-Southern Oscillation (ENSO) and North Atlantic Oscillation (NAO). Our review and synthesis (based on 561 species from 221 papers) reveals that population changes of mammals , birds and insects are strongly affected by major oceanic shifts or irregular oceanic changes, particularly in ENSO-and NAO-influenced regions (Pacific and Atlantic, respectively), providing clear evidence supporting Elton's BSCH. Mammal and insect populations tended to increase during positive ENSO phases. Bird populations tended to increase in positive NAO phases. Some species showed dual associations with both positive and negative phases of the same climate index (ENSO or NAO). These findings indicate that some taxa or regions are more or less vulnerable to climate fluctuations and that some geographical areas show multiple weather effects related to ENSO or NAO phases. Beyond confirming that animal populations are influenced by broad-scale climate variation, we document extensive patterns of variation among taxa and observe that the direct biotic and abiotic mechanisms for these broad-scale climate factors affecting animal populations are very poorly understood. A practical implication of our research is that changes in ENSO or NAO can be used as early signals for pest management and wildlife conservation. We advocate integrative studies at both broad and local scales to unravel the omnipresent effects of climate on animal populations to help address the challenge of conserving biodiversity in this era of accelerated climate change.
... For instance, Tables 2 and 3 display the incurred claims and paid losses of the direct compensation policy in the form of a triangle. Furthermore, we examine the residuals to ensure the existence of a chain-ladder data structure by employing the time series and lag plots, and the turning point test (Bhattacharyya 1984;Montgomery et al. 2015;Salvidio et al. 2016). Our findings reveal that the residuals are independent and identically distributed (IID), and the data conform with the proposed structure. ...
This study considers the risk management of insurance policies in line with the implementation of the new International Financial Reporting Standards 17. It applies the paid-incurred chain method to model the future unpaid losses by combining the information channels of both the incurred claims and paid losses. We propose the recovery of the empirical distribution of the outstanding claims liabilities associated with a group of contracts via moment-based density approximation. We determine the risk measures and adjustments that are compliant with the new standard using the Monte–Carlo simulation method and approximated distributions. The historical data on the aggregate Ontario automobile insurance claims over a 15-year period are analyzed to examine the appropriateness and accuracy of our approach.
... To determine the vulnerability of populations to changing environmental conditions, it is critical to link vital rates to ecological covariates that will be impacted by global change (Saracco & Rubenstein, 2019). Our IPM-BPVA revealed that (a) climate affects loon population dynamics via both reproduction and adult survival, (b) interactions between different climate variables result in complex patterns of population dynamics such that the effects of climatic conditions may take multiple years to become apparent in a long-lived, high-trophic level species (Crespin et al., 2006;Salvidio et al., 2016) and ( Northrup et al., 2019;Sohl, 2014). Here, we provide a more mechanistic link between population dynamics and global change drivers by modelling demographic parameters (e.g. ...
Together climate and land‐use change play a crucial role in determining species distribution and abundance, but measuring the simultaneous impacts of these processes on current and future population trajectories is challenging due to time lags, interactive effects and data limitations. Most approaches that relate multiple global change drivers to population changes have been based on occurrence or count data alone.
We leveraged three long‐term (1995–2019) datasets to develop a coupled integrated population model‐Bayesian population viability analysis (IPM‐BPVA) to project future survival and reproductive success for common loons Gavia immer in northern Wisconsin, USA, by explicitly linking vital rates to changes in climate and land use.
The winter North Atlantic Oscillation (NAO), a broad‐scale climate index, immediately preceding the breeding season and annual changes in developed land cover within breeding areas both had strongly negative influences on adult survival. Local summer rainfall was negatively related to fecundity, though this relationship was mediated by a lagged interaction with the winter NAO, suggesting a compensatory population‐level response to climate variability.
We compared population viability under 12 future scenarios of annual land‐use change, precipitation and NAO conditions. Under all scenarios, the loon population was expected to decline, yet the steepest declines were projected under positive NAO trends, as anticipated with ongoing climate change. Thus, loons breeding in the northern United States are likely to remain affected by climatic processes occurring thousands of miles away in the North Atlantic during the non‐breeding period of the annual cycle.
Our results reveal that climate and land‐use changes are differentially contributing to loon population declines along the southern edge of their breeding range and will continue to do so despite natural compensatory responses. We also demonstrate that concurrent analysis of multiple data types facilitates deeper understanding of the ecological implications of anthropogenic‐induced change occurring at multiple spatial scales. Our modelling approach can be used to project demographic responses of populations to varying environmental conditions while accounting for multiple sources of uncertainty, an increasingly pressing need in the face of unprecedented global change.
... In the study region, the species is found in humid forest habitats along small streams, but also in humid underground habitats such as natural and artificial caves (Salvidio et al. 2017). Here, in the last three decades, abundance has been estimated for several underground and forest floor populations, both by temporary removal sampling (Salvidio 2001(Salvidio , 2007Salvidio et al. 2016), and by binomial N-Mixture modelling (Costa et al. 2016). ...
Information on population abundance is important to correctly plan conservation and management of animal populations. In general, capture-mark-recapture (CMR) is considered the most robust technique to estimate population abundance, but it is costly in terms of time and effort. Recently, binomial N-mixture models, based on counts of unmarked individuals, have been widely employed to estimate abundance. These models have limits and their reliability has been criticized. In the majority of cases, multinomial N-mixture models based on multiple observer protocols, that are hierarchical extensions of simple CMR, are applied in estimating abundance of animals with large body size, conspicuous behavior or high detection probabilities. We applied and evaluated the reliability of a multinomial N-mixture modelling approach with multiple observer data to a small and cryptic terrestrial salamander, found in different habitats where populations possess different level of detectability. Estimates obtained with multinomial N-mixture models were compared to estimates obtained with classical methods, such as removal sampling, and their reliability has also been evaluated by simulations scenarios. Our results show that multinomial N-mixture models, applied within a multiple observer framework, give reliable and robust estimates of population abundance even when detection and density are relatively low. Therefore, multinomial N-mixture models appear efficient and cost-effective when planning and identifying management actions and conservation programs of small terrestrial animals such as amphibians and reptiles.
... The study of the salamander population abundance and distribution is part of a long-term research that began in 1996 and is still ongoing [26,27]. The data used in this study are those obtained from 2013 to 2019. ...
Subterranean habitats are characterized by buffered climatic conditions in comparison to contiguous surface environments and, in general, subterranean biological communities are considered to be relatively constant. However, although several studies have described the seasonal variation of subterranean communities, few analyzed their variability over successive years. The present research was conducted inside an artificial cave during seven successive summers, from 2013 to 2019. The parietal faunal community was sampled at regular intervals from outside to 21 m deep inside the cave. The community top predator is the cave salamander Speleomantes strinatii, while invertebrates, mainly adult flies, make up the rest of the faunal assemblage. Our findings indicate that the taxonomic composition and the spatial distribution of this community remained relatively constant over the seven-year study period, supporting previous findings. However, different environmental factors were shaping the distribution of predators and prey along the cave. Invertebrates were mainly affected by the illuminance, while salamanders were influenced by both illuminance and distance from the cave's entrance. The inter-annual spatial distribution of the salamander population was highly repeatable and age specific, confirming a gradual shift towards the deeper parts of the cave with an increasing age. In general, the spatial distribution along the cave of this prey-predator system remained relatively constant during the seven-year study, suggesting that strong selective constraints were in action, even in this relatively recent subterranean ecosystem.
... In Norway, the temporal variation of the spawning date or onset of activity of six amphibian species closely matches the variation of the NAO i (Forchhammer et al. 1998). In an Italian cave, the abundance of a terrestrial salamander varied in relation to the 1-year lagged winter NAO i , the negative winter values that are associated with humid and warm weather in this area increasing the survival of the young stages (Salvidio et al. 2015). Cayuela et al. (2017) show that NAO fluctuations affect the survival of amphibian species that have a fast demographic turnover while they affect the recruitment in species that have a slow turnover. ...
In the south of France, the so-called climate hiatus from 1998 to 2013 was associated with a late winter cooling which has affected the phenology of several reptiles and amphibian species, delaying their dates of first appearances in spring. This episode has been related to a period of frequently negative values of the North Atlantic Oscillation index (NAOi). The recent increase of this index after this episode marks the end of the “hiatus” and provides an opportunity to verify the impact of the North Atlantic Oscillation (NAO) on the fauna of the North Mediterranean region. Most of the emergence dates of amphibians and reptiles in spring have rapidly advanced from 1983 to 1997 and then receded or stabilized from 1998 to 2010. They began to advance again since 2010. These phenological changes covary with the temperature of February–March in the study area, which is itself related to the variations of the NAO index. These changes confirm the influence of the NAO on the phenology of terrestrial organisms in northern Mediterranean where its influence is sometimes assumed to be attenuated.
... Literature data provide a number of examples on how autumn and winter temperature affect amphibians, from positive effects of higher temperatures on the agile frog (Combes et al. 2018) to negative ones for B. bufo (Reading and Clarke 1995;Reading 2007). The positive influence of autumn and winter precipitation on amphibian populations was documented in a few research projects (Jensen et al. 2003;Hartel 2008a;Cayuela et al. 2014;Benard 2015;Salvidio et al. 2016;Combes et al. 2018) and higher humidity should decrease desiccation risks during hibernation (Combes et al. 2018). In this study, we revealed a trend towards an increase in winter humidity over the years of monitoring, while temperature variation patterns seemed random. ...
We monitored the population size of the agile frog ( Ranadalmatina ) and the common toad ( Bufobufo ) from 2011 or 2012, respectively, to the year 2017 at a syntopic breeding site in the vicinity of Belgrade. Adult R.dalmatina population size had minor fluctuations during the years of study (from 351 to 108 frogs). On the contrary, the adult B.bufo population was widely fluctuating towards decline (from 1158 to 141 toads). In both species, population fluctuations were not significantly related to variation of meteorological parameters (air temperature, humidity, precipitation). Density dependence effects on population size were not detected in either species. Apart from possible effects of climate change, the indicated trend towards decline of the monitored B.bufo population could also be the outcome of common population fluctuations or of increasing anthropogenic impact (vicinity of settlement and agricultural land). More years of monitoring more than one population are required to obtain precise information. Nevertheless, our results seem to be coherent with other studies that recommend conservation action for this species.
... In the past two decades, a growing number of studies have shown that the NAO influences abundance and demographic parameters in several taxa, including birds (e.g., Nevoux, Barbraud, & Barbraud, 2008), mammals (e.g., Post & Stenseth, 1998), amphibians (Salvidio, Oneto, Ottonello, & Pastorino, 2016), and fishes (e.g., Attrill & Power, 2002). In mammals and birds, the NAO has varying effects on survival, sometimes in combination with other environmental factors (e.g., level of food resources, predation) or with internal state variables (e.g., age, sex) (Coulson et al., 2001;Payo-Payo, Genovart, Bertolero, Pradel, & Oro, 2016;Pokallus & Pauli, 2015). ...
Over the last three decades, climate abnormalities have been reported to be involved in biodiversity decline by affecting population dynamics. A growing number of studies have shown that the North Atlantic Oscillation (NAO) influences the demographic parameters of a wide range of plant and animal taxa in different ways. Life history theory could help to understand these different demographic responses to the NAO. Indeed, theory states that the impact of weather variation on a species' demographic traits should depend on its position along the fast-slow continuum. In particular, it is expected that NAO would have a higher impact on recruitment than on adult survival in slow species while the opposite pattern is expected occur in fast species. To test these predictions, we used long-term capture-recapture datasets (more than 15,000 individuals marked from 1965-2015) on different surveyed populations of three amphibian species in Western Europe: Triturus cristatus, Bombina variegata and Salamandra salamandra. Despite substantial intraspecific variation, our study revealed that these three species differ in their position on a slow-fast gradient of pace of life. Our results also suggest that the differences in life history tactics influences amphibian responses to NAO fluctuations: adult survival was most affected by the NAO in the species with the fastest pace of life (T. cristatus), whereas recruitment was most impacted in species with a slower pace of life (B. variegata and S. salamandra). In the context of climate change, our findings suggest that the capacity of organisms to deal with future changes in NAO values could be closely linked to their position on the fast-slow continuum. This article is protected by copyright. All rights reserved.
Herps, especially amphibians, are particularly susceptible to climate change, since temperature tightly controls many parameters of their biological cycle - above all, their phenology. The timing of herps' activity or migration period - in particular the dates of their first appearance in spring and first breeding - and the shift to earlier dates in response to warming since the last quarter of the 20(th) century has often been described up to now as a nearly monotonic trend towards earlier phenological events. In this study, we used citizen science data opportunistically collected on reptiles and amphibians in the northern Mediterranean basin over a period of 32 years to explore temporal variations in herp phenology. For 17 common species, we measured shifts in the date of the species' first spring appearance - which may be the result of current changes in climate - and regressed the first appearance date against temperatures and precipitations. Our results confirmed the expected overall trend towards earlier first spring appearances from 1983 to 1997, and show that the first appearance date of both reptiles and amphibians fits well with the temperature in late winter. However, the trend towards earlier dates was stopped or even reversed in most species between 1998 and 2013. We interpret this reversal as a response to cooling related to the North Atlantic Oscillation (NAO) in the late winter and early spring. During the positive NAO episodes, for certain species only (mainly amphibians), the effect of a warm weather, which tends to advance the phenology, seems to be counterbalanced by the adverse effects of the relative dryness. This article is protected by copyright. All rights reserved.
Reduction in body size is a major response to climate change, yet evidence in globally imperiled amphibians is lacking. Shifts in average population body size could indicate either plasticity in the growth response to changing climates through changes in allocation and energetics, or through selection for decreased size where energy is limiting. We compared historic and contemporary size measurements in 15 Plethodon species from 102 populations (9450 individuals) and found that six species exhibited significant reductions in body size over 55 years. Biophysical models, accounting for actual changes in moisture and air temperature over that period, showed a 7.1-7.9% increase in metabolic expenditure at three latitudes but showed no change in annual duration of activity. Reduced size was greatest at southern latitudes in regions experiencing the greatest drying and warming. Our results are consistent with a plastic response of body size to climate change through reductions in body size as mediated through increased metabolism. These rapid reductions in body size over the past few decades have significance for the susceptibility of amphibians to environmental change, and relevance for whether adaptation can keep pace with climate change in the future.
Probst, W. N., Stelzenmüller, V., and Fock, H. 2012. Using cross-correlations to assess the relationship between time-lagged pressure and state indicators: an exemplary analysis of North Sea fish population indicators. – ICES Journal of Marine Science, 69: 670–681.
A sustainable ecosystem-based management, as postulated by the European Union-Marine Strategy Framework Directive (MSFD), requires a sound understanding of the cause–effect relationships between human pressures and ecosystem states. In this study, cross-correlations are used to introduce a protocol for the analysis of time-lagged relationships between pressure and state indicators. To perform meaningful cross-correlations, the time-series of the pressure and the state indicator should be prewhitened by fitting autoregressive integrated moving average models to the pressure indicator time-series. This study provides some theoretical examples on the implications of non-prewhitened and prewhitened cross-correlations and exemplifies the use of prewhitened cross-correlations to compare the pressure–state relationship of a well-established indicator suite vs. the relationship of a new indicator proposed under the MSFD. The established indicator suite is fishing mortality (F) vs. spawning-stock biomass (SSB), the new indicator suite is F vs. the 95% percentile of the length frequency distribution (L95). The L95 aims to characterize the proportion of large individuals within a population. The prewhitened cross-correlations for F and SSB are significant for all four analysed species (cod, haddock, saithe, and plaice), the L95 is correlated with F for cod, haddock, and saithe. However, the L95 was also influenced by the annual survey catch and recruitment.
The North Atlantic Oscillation (NAO) is a large-scale climate teleconnection that coincides with worldwide changes in weather. Its impacts have been documented at large scales, particularly in Europe, but not as much at regional scales. Furthermore, despite documented impacts on ecological dynamics in Europe, the NAO's influence on North American biota has been somewhat overlooked. This paper examines long-term temperature and precipitation trends in the southern Appalachian Mountain region-a region well known for its biotic diversity, particularly in salamander species-and examines the connections between these trends and NAO cycles. To connect the NAO phase shifts with southern Appalachian ecology, trends in stream salamander abundance are also examined as a function of the NAO index. The results reported here indicate no substantial long-term warming or precipitation trends in the southern Appalachians and suggest a strong relationship between cool season (November-April) temperature and precipitation and the NAO. More importantly, trends in stream salamander abundance are best explained by variation in the NAO as salamanders are most plentiful during the warmer, wetter phases.
This study examines teleconnections between the North Atlantic Oscillation (NAO) and the wave climate of the northwestern Mediterranean Sea (NWN,1), defined by the monthly mean significant wave height (SWH and the 95(th) percentile significant wave height (95(th) percentile SWH), in the period ranging from 1958 to 2001. The data analyzed comes from the multidecadul hindcast over Europe carried out during the HIPOCAS project. In order to avoid fictitious cross-correlations, data were prewhitened by fitting a p-order autoregressive model. To split the temporal and spatial variability. an EOF encoding technique was applied to residuals before searching for teleconnections. We found the northwestern Mediterranean wave climate to be influenced by the North Atlantic Oscillation (NAO) with an instantaneous response. When the NAO is in its positive phase, positive anomalies in the SWH and the 95(th) percentile SWH appear in the area between the Balearic Islands, the Gulf of Lions and the Catalonian coast.
A Speleomantes ambrosii population living in an artificial tunnel in NW Italy was studied for two consecutive years. Activity on the walls varied cyclically in relation to seasonal temperatures and food abundance. The main food item was the trogloxenic dipteran Limonia nubeculosa, which accounted for more than 80% of the total ingested prey by volume. Juvenile cave salamanders had a broader trophic nich than adults. Oviposition and juvenile recruitment appeared to be seasonal. The spatial distribution inside the tunnel was related to microhabitat heterogeneity and particularly to the distance from the entrance. Juveniles were observed outside or close to the entrance more often than adults. Movement of adult salamanders were generally low and averaged 7 cm/day; some repeatedly recaptured individuals had a mean home range of 6 m2.
Posthatching parental care is known in amphibians for frogs and caecilians but, thus far, has never been reported for salamanders. Here, we describe the parental behavior of a female Northwest Italian Cave Salamander, Speleomantes strinatii, from egg deposition to nest site abandonment. The female was kept in seminatural conditions and filmed in complete darkness by an infrared video camera. In November 2007, the female laid nine eggs in a small depression of the terrarium floor, displaced the clutch with hind limbs, and showed antipredator behaviors toward a conspecific female and an intruding Roof Rat (Rattus rattus). During egg brooding, the female remained in contact with the clutch for about 98% of the time. In September 2008, two young hatched and shared the nesting site for six weeks with the female, which attended the nesting site for 87% of the time. Hatchlings repeatedly climbed over the female's body, lying on her for hours. The female walked out of the nesting site with a young on its back twice. These prolonged skin contacts between parent and offspring should be considered as the first certain case of young attendance in salamanders. This behavior may be related to increased survival of hatchlings during their first weeks of life, when young are particularly vulnerable to predation, skin infection, and dehydration.
Mediterranean basins are known for their susceptibility to water stress conditions resulting from a reduction in winter-season precipitation. This region is also prone to the effects of the North Atlantic Oscillation (NAO), a large-scale climatic pattern associated with a displacement of air mass between the arctic and the subtropical Atlantic. Even though previous studies have demonstrated the impact of the NAO on winter climate conditions in Europe and Northern Africa, it is still un-clear to what extent the NAO is related to hydroclimatic patterns in Mediterranean areas and whether it can explain its recent drought history. To this end, this study investigates the interdependence between the NAO and winter precipitation, river flow and temperature in two Mediterranean regions: Southern Italy and Nile Delta (Egypt). The outcomes show the presence of significant connections between the NAO, winter rainfall and river discharge.
Links between climatic conditions in the eastern equatorial Pacific and extratropical ecological processes remain unexplored. The analysis of a 20-year time series of spatial and numeric dynamics of a threatened Mediterranean bird suggests, however, that such couplings can be remarkably complex. By providing a new ecological time-series modelling approach, we were able to dissect the joint effects of the El Niño/Southern Oscillation (ENSO), the North Atlantic Oscillation (NAO), regional weather, population density and stochastic variability on the expansion dynamics of the White-headed duck (Oxyura leococephala) in Spain. Our results suggest that the spatial and numeric dynamics of ducks between peak brood emergence and wintering were simultaneously affected by different climatic phenomena during different phases of their global cycles, involving time lags in the numeric dynamics. Strikingly, our results point to both the NAO and the ENSO as potentially major factors simultaneously forcing ecological processes in the Northern Hemisphere, and suggest a new pathway for non-additive effects of climate in ecology.
Predicting how bird populations may respond to climate change is a major challenge which could be addressed by understanding how past environmental processes have driven the variations of breeding population size and productivity. In inhabited regions, this issue may be complicated by the interference associated with heterogeneous levels of habitat management. Here, we have explored how several hydrological variables influenced the breeding of the Greater Flamingo Phoenicopterus roseus in the Camargue (Rhone delta, southern France) over a 28-year period (1974–2001). In this region, Flamingos breed in a commercial salt pan. They forage in both salt pans and adjacent brackish lagoons. We hypothesized that breeding numbers, productivity and body condition of chicks at fledging were influenced positively by water levels of the Vaccares, the main lagoon of the delta, in spring (water and food availability) and the Rhone discharge in winter (nutrient availability in the salt pans). We controlled for variations of the flooding date of the breeding salt pan by the salt company and the size of the breeding island. We first found the Vaccares water levels and Rhone discharge to be negatively correlated with the North Atlantic Oscillation (NAO). Secondly, the number of Flamingo breeding pairs (range 3560–22 200) increased by 1767 ± 1418 (95% CI) with a 10-day advance of the flooding date of the breeding salt pan and by 1146 ± 1081 per 10-cm water level rise in the Vaccares. Productivity was 0.46 ± 0.41 chicks per pair and could not be explained by any of the variables considered. Finally, chick body condition decreased with the number of breeding pairs and Rhone discharge. Our results show that (1) this intensely managed system remains sensitive to large-scale climate variations, (2) the breeding of the Greater Flamingo is affected by both climate variations and management of the salt pan, and (3) the expected enhancement of delta productivity by high river discharge was absent, probably prevented by dykes and embankments along the river. The response of bird populations to climate variations can thus be complex in intensely managed biological systems as found in the Mediterranean. We encourage pursuing such analyses incorporating anthropogenic variables explicitly in order to expand our capacity to make inference on the future of these systems.
Large-scale climate indices have received much attention in recent years in ecology-climate research due to the advantages
they have over typically used local weather variables, such as temperature or rainfall. In the Mediterranean, the North Atlantic
Oscillation (NAO) is a major forcing of climate patterns, especially precipitation. More than 60 studies to date have demonstrated
the effects of the NAO on both terrestrial and aquatic Mediterranean ecosystems. In terrestrial ecosystems, the NAO affects
the phenology and growth of plants and crop yields. It also affects the condition and diet of mammals and disease-related
mortality in amphibians. The effects of the NAO are probably better known in marine ecosystems, where the impact on the hydrodynamics
of the water column and currents is felt in the dynamics of populations from plankton to fishes in both pelagic and benthonic
environments. Additionally, birds are an especially well studied taxon when it comes to effects of the NAO. The NAO has been
shown to affect the population dynamics of water birds by impacting the availability and extent of their habitat and by influencing
dispersal decisions of individuals. The NAO plays an essential role in the migration of birds throughout the Mediterranean
basin, and it is probably a reason for the observed advance of arrival dates during the spring in Europe. In spite of the
notable number of studies carried out to date, we are far from knowing accurately the ecological impacts of the NAO on Mediterranean
ecosystems. More efforts are needed to understand regional differences in the NAO effects within the Mediterranean basin and
how they compare with more northern latitudes of Europe.
KeywordsBirds-Climate-Ecosystem-Phenology-Review
A standard principal component analysis has been performed over the Mediterranean and over the larger European region on
monthly precipitation anomalies for the winters between 1979 and 1995. The main centres of action of the associated EOFs are
very similar for the two regions and the two sets of PCs are highly correlated with each other. Focusing on the Mediterranean
region, the same analysis has been performed using 500 hPa geopotential height monthly anomalies taken from the operational
NCEP analysis. Comparing the two sets of PCs associated with upper-air and surface data, a strong correlation has been found
suggesting the presence of a two-way link between regional precipitation patterns and large-scale circulation anomalies. For
both fields, the largest fraction of variance is explained by the North Atlantic Oscillation, while smaller but still substantial
fractions are explained by other known patterns of large-scale variability such as the Eastern Atlantic pattern and the Euro-Atlantic
blocking. No detectable connection has been found between Mediterranean precipitation patterns and El Niño SST anomalies during
winter. With respect to temporal variability, significant trends have been found over most European areas during the winters
considered. The associated pattern is characterised by a substantial increase of precipitation over western Scandinavia and
a general decrease over southern Europe. This result is confirmed by analysing data from stations located in northern Italy.
Large changes in the wintertime atmospheric circulation have occurred over the past two decades over the ocean basins of the Northern Hemisphere, and these changes have had a profound effect on regional distributions of surface temperature and precipitation. The changes over the North Pacific have been well documented and have contributed to increases in temperatures across Alaska and much of western North America and to decreases in sea surface temperatures over the central North Pacific. The variations over the North Atlantic are related to changes in the North Atlantic Oscillation (NAO). Over the past 130 years, the NAO has exhibited considerable variability at quasi-biennial and quasi-decadal time scales, and the latter have become especially pronounced the second half of this century. Since 1980, the NAO has tended to remain in one extreme phase and has accounted for a substantial part of the observed wintertime surface warming over Europe and downstream over Eurasia and cooling in the northwest Atlantic. Anomalies in precipitation, including dry wintertime conditions over southern Europe and the Mediterranean and wetter-than-normal conditions over northern Europe and Scandinavia since 1980, are also linked to the behavior of the NAO. Changes in the monthly mean flow over the Atlantic are accompanied by a northward shift in the storm tracks and associated synoptic eddy activity, and these changes help to reinforce and maintain the anomalous mean circulation in the upper troposphere. It is important that studies of trends in local climate records, such as those from high elevation sites, recognize the presence of strong regional patterns of change associated with phenomena like the NAO.
It has been suggested that Plethodontid salamanders are excellent candidates for indicating ecosystem health. However, detailed, long-term data sets of their populations are rare, limiting our understanding of the demographic processes underlying their population fluctuations. Here we present a demographic analysis based on a 1996-2008 data set on an underground population of Speleomantes strinatii (Aellen) in NW Italy. We utilised a Bayesian state-space approach allowing us to parameterise a stage-structured Lefkovitch model. We used all the available population data from annual temporary removal experiments to provide us with the baseline data on the numbers of juveniles, subadults and adult males and females present at any given time.
Sampling the posterior chains of the converged state-space model gives us the likelihood distributions of the state-specific demographic rates and the associated uncertainty of these estimates. Analysing the resulting parameterised Lefkovitch matrices shows that the population growth is very close to 1, and that at population equilibrium we expect half of the individuals present to be adults of reproductive age which is what we also observe in the data. Elasticity analysis shows that adult survival is the key determinant for population growth.
This analysis demonstrates how an understanding of population demography can be gained from structured population data even in a case where following marked individuals over their whole lifespan is not practical.
Whereas the El Niño Southern Oscillation (ENSO) affects weather and climate variability worldwide, the North Atlantic Oscillation (NAO) represents the dominant climate pattern in the North Atlantic region. Both climate systems have been demonstrated to considerably influence ecological processes. Several other large-scale climate patterns also exist. Although less well known outside the field of climatology, these patterns are also likely to be of ecological interest. We provide an overview of these climate patterns within the context of the ecological effects of climate variability. The application of climate indices by definition reduces complex space and time variability into simple measures, 'packages of weather'. The disadvantages of using global climate indices are all related to the fact that another level of problems are added to the ecology-climate interface, namely the link between global climate indices and local climate. We identify issues related to: (i) spatial variation; (ii) seasonality; (iii) non-stationarity; (iv) nonlinearity; and (v) lack of correlation in the relationship between global and local climate. The main advantages of using global climate indices are: (i) biological effects may be related more strongly to global indices than to any single local climate variable; (ii) it helps to avoid problems of model selection; (iii) it opens the possibility for ecologists to make predictions; and (iv) they are typically readily available on Internet.
There is general consensus that climate change has contributed to the observed decline, and extinction, of many amphibian species throughout the world. However, the mechanisms of its effects remain unclear. A laboratory study in 1980-1981 in which temperate zone amphibians that were prevented from hibernating had decreased growth rates, matured at a smaller size and had increased mortality compared with those that hibernated suggested one possible mechanism. I used data from a field study of common toads (Bufo bufo) in the UK, between 1983 and 2005, to determine whether this also occurs in the field. The results demonstrated two pathways by which global warming may cause amphibian declines. First, there was a clear relationship between a decline in the body condition of female common toads and the occurrence of warmer than average years since 1983. This was paralleled by a decline in their annual survival rates with the relationship between these two declines being highly correlated. Second, there was a significant relationship between the occurrence of mild winters and a reduction in female body size, resulting in fewer eggs being laid annually. Climate warming can, therefore, act on wild temperate zone amphibians by deleteriously affecting their physiology, during and after hibernation, causing increased female mortality rates and decreased fecundity in survivors.
Amphibian species are declining at an alarming rate on a global scale in large part owing to an infectious disease caused by the chytridiomycete fungus, Batrachochytrium dendrobatidis. This disease of amphibians has recently emerged within Europe, but knowledge of its effects on amphibian assemblages remains poor. Importantly, little is known about the environmental envelope that is associated with chytridiomycosis in Europe and the potential for climate change to drive future disease dynamics. Here, we use long-term observations on amphibian population dynamics in the Peñalara Natural Park, Spain, to investigate the link between climate change and chytridiomycosis. Our analysis shows a significant association between change in local climatic variables and the occurrence of chytridiomycosis within this region. Specifically, we show that rising temperature is linked to the occurrence of chytrid-related disease, consistent with the chytrid-thermal-optimum hypothesis. We show that these local variables are driven by general circulation patterns, principally the North Atlantic Oscillation. Given that B. dendrobatidis is known to be broadly distributed across Europe, there is now an urgent need to assess the generality of our finding and determine whether climate-driven epidemics may be expected to impact on amphibian species across the wider region.
Time series analysis has been used to evaluate the mechanisms regulating population dynamics of mammals and insects, but has been rarely applied to amphibian populations. In this study, the influence of endogenous (density-dependent) and exogenous (density-independent) factors regulating population dynamics of the terrestrial plethodontid salamander Speleomantes strinatii was analysed by means of time series and multiple regression analyses. During the period 1993-2005, S. strinatii population abundance, estimated by a standardised temporary removal method, displayed relatively low fluctuations, and the autocorrelation function (ACF) analysis showed that the time series had a noncyclic structure. The partial rate correlation function (PRCF) indicated that a strong first-order negative feedback dominated the endogenous dynamics. Stepwise multiple regression analysis showed that the only climatic factor influencing population growth rate was the minimum winter temperature. Thus, at least during the study period, endogenous, density-dependent negative feedback was the main factor affecting the growth rate of the salamander population, whereas stochastic environmental variables, such as temperature and rainfall, seemed to play a minor role in regulation. These results stress the importance of considering both exogenous and endogenous factors when analysing amphibian long-term population dynamics.
Climate change is affecting the phenology of seasonal events in Europe and the Northern Hemisphere, as shown by several studies of birds' timing of migration and reproduction. Here, we analyse the long-term (1982-2006) trends of first arrival dates of four long-distance migratory birds [swift (Apus apus), nightingale (Luscinia megarhynchos), barn swallow (Hirundo rustica), and house martin (Delichon urbicum)] and first egg laying dates of two migrant (swift, barn swallow) and two resident species [starling (Sturnus vulgaris), Italian sparrow (Passer italiae)] at a study site in northern Italy. We also addressed the effects of local weather (temperature and precipitation) and a climate index (the North Atlantic Oscillation, NAO) on the interannual variability of phenological events. We found that the swift and the barn swallow significantly advanced both arrival and laying dates, whereas all other species did not show any significant temporal trend in either arrival or laying date. The earlier arrival of swifts was explained by increasing local temperatures in April, whereas this was not the case for arrival dates of swallows and first egg laying dates of both species. In addition, arrival dates of house martins were earlier following high NAO winters, while nightingale arrival was earlier when local spring rainfall was greater. Finally, Italian sparrow onset of reproduction was anticipated by greater spring rainfall, but delayed by high spring NAO anomalies, and swift's onset of reproduction was anticipated by abundant rainfall prior to reproduction. There were no significant temporal trends in the interval between onset of laying and arrival in either the swift or the barn swallow. Our findings therefore indicate that birds may show idiosyncratic responses to climate variability at different spatial scales, though some species may be adjusting their calendar to rapidly changing climatic conditions.
Greenland ice-core data have revealed large decadal climate variations over the North Atlantic that can be related to a major
source of low-frequency variability, the North Atlantic Oscillation. Over the past decade, the Oscillation has remained in
one extreme phase during the winters, contributing significantly to the recent wintertime warmth across Europe and to cold
conditions in the northwest Atlantic. An evaluation of the atmospheric moisture budget reveals coherent large-scale changes
since 1980 that are linked to recent dry conditions over southern Europe and the Mediterranean, whereas northern Europe and
parts of Scandinavia have generally experienced wetter than normal conditions.
A knowledge of animal population dynamics is essential for the proper management of natural resources and the environment. This book, now available in paperback, develops basic concepts and a rigorous methodology for the analysis of animal population dynamics to identify the underlying mechanisms.
Preface Acknowledgements 1. Challenges to community theory 2. Equilibrium and stability in natural populations 3. An introduction to the variety of salamander life histories 4. Communities of pond-inhabiting salamanders 5. Communities of terrestrial salamanders 6. Communities of streamside slaamanders 7. Evolution in salamander communities: experimental tests 8. Salamanders in future ecological research References Indexes.
Greenland ice-core data have revealed large decadal climate variations over the North Atlantic that can be related to a major source of low-frequency variability, the North Atlantic Oscillation. Over the past decade, the Oscillation has remained in one extreme phase during the winters, contributing significantly to the recent wintertime warmth across Europe and to cold conditions in the northwest Atlantic. An evaluation of the atmospheric moisture budget reveals coherent large-scale changes since 1980 that are linked to recent dry conditions over southern Europe and the Mediterranean, whereas northern Europe and parts of Scandinavia have generally experienced wetter than normal conditions.
When Keith (1963) published his ‘Wildlife’s 10-year cycle’, available information on the theme was minimal. Many theories were no more than conjectures. In 1961, realizing that further theorizing would get him nowhere, Keith and a team of researchers from the Wisconsin school of wildlife ecology, launched a long-term field study on snowshoe hare (Lepus americanus) populations near Rochester, Alberta. A number of important papers from this study have appeared since then, including the monograph (Keith and Windberg, 1978) that provides a nearly complete 15-year set of demographic data. I shall call this work ‘the Rochester study’.
Nothing has so intrigued and fascinated many naturalists and ecologists as the persistent 10-year cycle of Canada lynx, Lynx canadensis. The well-known archives of the fur trade between the Hudson’s Bay Company and the Canadian trappers in the past two centuries have been a rich source of speculation about the cause of the cycle. As a result, diverse theories exist in the literature. However, many of these ideas were not substantiated by observations, and some statistical analyses ignored ecological mechanisms.
Abstract: Information on individual trophic specialization may be relevant to better understand the ecological adaptation of populations to their environment and the evolution of their realized trophic niche. In this study, we analysed the trophic specialization at the individual level in a population of the plethodontid Northwest Italian Cave Salamander (Speleomantes strinatii (Aellen, 1958)), a terrestrial generalist predator. Salamanders were sampled in northwestern Italy on the forest floor in autumn (n = 49) and spring (n = 47) along with their available prey. In autumn, when trophic resources showed a twofold reduction in abundance, the population trophic niche width (TNW = 2.58) was significantly broader than during spring (TNW = 2.25), and in both seasons, individual specialization (IS) was significantly higher than expected by chance (P = 0.001). There were no sexual or
ontogenetic differences in IS within each season, but IS in autumn was significantly higher than in spring (IS = 0.34 and IS = 0.41, respectively; P = 0.01). These findings are in accordance with the niche variation hypothesis, which predicts a positive relationship between TNW and IS. Therefore, while the population became more generalist, individual salamanders shifted towards a more specialized diet by adapting their feeding behaviour to changes in prey availability.
Trophic niche may be the most important ecological dimension for some vertebrate groups and in particular for terrestrial amphibians, that are important predators of soil invertebrates. In general, resource partitioning occurs between syntopic species with similar ecological niches, and coexistence patterns seem to be regulated by temporal resource variability. However most of the generalization on foraging strategies of terrestrial salamanders are extrapolated from studies on New World temperate species, thus we investigated the seasonal effect of resource variation in an European forest ecosystem, in which two ecologically similar but phylogenetically distinct salamander species are found. The diet of adult and juvenile cave salamanders (Speleomantes strinati), and of adult spectacled salamander (Sala-mandrina perspicillata) was obtained by stomach flushing, and results showed large seasonal changes both in prey availability and in salamander realised trophic niche. Values of trophic diversity were similar and niche overlaps were large among all salamander groups in spring, during high prey availability. Conversely in autumn, when a two-fold reduction in prey biomass was observed, there was a clear niche partitioning as the smaller S. perspicillata shifted from a generalist to a specialized trophic strategy. Juvenile Speleomantes strinatii, that largely overlapped in size with S. perspicillata, did not show any change in diet, suggesting that the feeding strategies were species-specific and not size-mediated. The observed patterns of variation in feeding ecology indicate that similar predators may react differently to changing prey availability to enhance niche partitioning. We also observed an increased energy intake during autumn for S perspicillata and S. strinatii juveniles, possibly related to differences in microhabitat use and activity patterns. Ó 2012 Elsevier Masson SAS. All rights reserved.
Recently, climate change research in ecology has embraced the use of large-scale climate indices in long-term, retrospective studies. In most instances, these indices are related to large-scale teleconnection and atmospheric patterns of which over a dozen have been identified. Although most of these relate to different geographical areas, many are related and interact. Consequently, even the simple task of selecting one to use in ecological research has become complicated, despite our ability to disentangle the results from analyses involving large-scale climate indices. Leaning upon recent reviews of the definition and functioning of large-scale climate indices, as well as reviews on the relationship between these and concomitant changes in ecological variables, we focus here on the usefulness of large-scale climate indices in different aspects of climate change ecology. By providing a general framework for using climate indices, we illustrate the potential advantages of their utility by integrating three case histories focusing on two groups of evolutionarily distinct organisms: birds and mammals.
Climate can interact with population dynamics in complex ways. In this study we describe how climatic factors influenced the dynamics of an amphibian metapopulation over 12 years through interactions with survival, recruitment and dispersal. Low annual survival of great crested newts (Triturus cristatus) was related to mild winters and heavy rainfall, which impacted the metapopulation at the regional level. Consequently, survival varied between years but not between subpopulations. Despite this regional effect, the four subpopulations were largely asynchronous in their dynamics. Three out of the four subpopulations suffered reproductive failure in most years, and recruitment to the metapopulation relied on one source. Variation in recruitment and juvenile dispersal was therefore probably driving asynchrony in population dynamics. At least one subpopulation went extinct over the 12 year period. These trends are consistent with simulations of the system, which predicted that two subpopulations had an extinction risk of >50% if adult survival fell below 30% in combination with low juvenile survival. Intermittent recruitment may therefore only result in population persistence if compensated for by relatively high adult survival. Mild winters may consequently reduce the viability of amphibian metapopulations. In the face of climate change, conservation actions may be needed at the local scale to compensate for reduced adult survival. These would need to include management to enhance recruitment, connectivity and dispersal.
Consisting of more than six thousand species, amphibians are more diverse than mammals and are found on every continent save Antarctica. Despite the abundance and diversity of these animals, many aspects of the biology of amphibians remain unstudied or misunderstood. The Ecology and Behavior of Amphibians aims to fill this gap in the literature on this remarkable taxon. It is a celebration of the diversity of amphibian life and the ecological and behavioral adaptations that have made it a successful component of terrestrial and aquatic ecosystems. Synthesizing seventy years of research on amphibian biology, Kentwood D. Wells addresses all major areas of inquiry, including phylogeny, classification, and morphology; aspects of physiological ecology such as water and temperature relations, respiration, metabolism, and energetics; movements and orientation; communication and social behavior; reproduction and parental care; ecology and behavior of amphibian larvae and ecological aspects of metamorphosis; ecological impact of predation on amphibian populations and antipredator defenses; and aspects of amphibian community ecology. With an eye towards modern concerns, The Ecology and Behavior of Amphibians concludes with a chapter devoted to amphibian conservation. An unprecedented scholarly contribution to amphibian biology, this book is eagerly anticipated among specialists.
Two contrasting approaches to the analysis of population dynamics are currently popular: demographic approaches where the associations between demographic rates and statistics summarizing the population dynamics are identified; and time series approaches where the associations between population dynamics, population density, and environmental covariates are investigated. In this paper, we develop an approach to combine these methods and apply it to detailed data from Soay sheep (Ovis aries). We examine how density dependence and climate contribute to fluctuations in population size via age- and sex-specific demographic rates, and how fluctuations in demographic structure influence population dynamics. Density dependence contributes most, followed by climatic variation, age structure fluctuations and interactions between density and climate. We then simplify the density-dependent, stochastic, age-structured demographic model and derive a new phenomenological time series which captures the dynamics better than previously selected functions. The simple method we develop has potential to provide substantial insight into the relative contributions of population and individual-level processes to the dynamics of populations in stochastic environments.
Razzetti E (eds) Fauna d'Italia. 42, Amphibia. Edizioni Calderini Bayesian salamanders: analysing the demography of an underground population of the European plethodontid Speleomantes strinatii with state-space modelling
- B Lanza B Lanza
- F Andreone
- Ma Bologna
- C Corti
- −156 Bologna
- L Lindstrom
- R Reeve
- S Salvidio
Lanza B (2007) Speleomantes strinatii (Aellen, 1958) In: Lanza
B, Andreone F, Bologna MA, Corti C, Razzetti E (eds)
Fauna d'Italia. 42, Amphibia. Edizioni Calderini, Bologna
152−156
Lindstrom L, Reeve R, Salvidio S (2010) Bayesian salamanders:
analysing the demography of an underground population of the
European plethodontid Speleomantes strinatii with state-space
modelling. BMC Ecol 10:4
The ecology and behaviour of amphibians Capturerecapture removal methods for sampling closed populations. Los Alamos National Laboratory 8787 NERP Analysis and management of animal populations Age structure matters for alpine ibex population dynamics
- Kd Wells
- Dr Anderson
- Kp Burnham
- Dl Otis
Wells KD (2007) The ecology and behaviour of amphibians. Chicago
University Press
White GC, Anderson DR, Burnham KP, Otis DL (1982) Capturerecapture removal methods for sampling closed populations. Los
Alamos National Laboratory 8787 NERP, Los Alamos
Williams BK, Conroy MJ, Nichols JD (2001) Analysis and management
of animal populations. Academic Press, San Diego
Yoccoz NG, Gaillard J-M (2006) Age structure matters for alpine ibex
population dynamics: comment on Lima & Berryman (2006).
Influence of the NAO on the northwestern Mediterranean wave climate
- P J Brockwell
- R Davies
Brockwell PJ, Davies R (2002) Introduction to time series analysis and
forecasting, 2nd edn. Springer, New York
Cañellas B, Orfila A, Méndez F, Álvarez A, Tintoré J (2010) Influence of
the NAO on the northwestern Mediterranean wave climate. Sci Mar
75:55-64
Widespread rapid reductions in body size of Appalachian salamanders in response to climate change
- Nm Caruso
- M Sears
- Dc Adams
- Kr Lips
Ecological impacts of the North Atlantic Oscillation (NAO) in Mediterranean ecosystems In: Vicente-Serr ano SM, Tr igo RM ( eds) Hydrological, socioeconomic and ecological impacts of the North Atlantic Oscillation in the Mediterranean Region
- O Gordo
- C Barriocanal
- D Robson
Gordo O, Barriocanal C, Robson D (2011) Ecological impacts of
the North Atlantic Oscillation (NAO) in Mediterranean ecosystems In: Vicente-Serr ano SM, Tr igo RM ( eds)
Hydrological, socioeconomic and ecological impacts of the
North Atlantic Oscillation in the Mediterranean Region.
Springer Science + Business Media B.V
Speleomantes strinatii (Aellen
- B Lanza B Lanza
- F Andreone
- Ma Bologna
- C Corti
- E Razzetti
Widespread rapid reductions in body size of Appalachian salamanders in response to climate change
- N M Caruso
- M Sears
- D C Adams
- K R Lips
Caruso NM, Sears M, Adams DC, Lips KR (2014) Widespread rapid
reductions in body size of Appalachian salamanders in response to
climate change. Glob Change Biol 20:1751-1759