scholarly journals First estimates of survival and densities of invasive alien Eastern cottontail (Sylvilagus floridanus) in Italy: a Bayesian robust design approach

2020 ◽  
Author(s):  
Jacopo Cerri ◽  
Laura Gola ◽  
Aurelio Perrone ◽  
Sandro Bertolino
Keyword(s):  
North America ◽  
Robust Design ◽  
Native Species ◽  
Survival Rates ◽  
High Survival ◽  
Sylvilagus Floridanus ◽  
Capture Recapture ◽  
Males And Females ◽  
Eastern Cottontail ◽  
Selection Of

The Eastern cottontail (Sylvilagus floridanus) has become invasive in Central and Northern Italy, where it affects prey-predator dynamics between native species. Although many different studies explored survival rates and the density of cottontails in North America, no information is available for its invasive range. Between December 2003 and October 2005, a capture-recapture scheme for Eastern cottontails was enforced on the Orba River, Italy. We fitted a Bayesian version of the Pollock’s Closed Robust Design to estimate the survival of adult male and female cottontails (n=258) and their density in the study area. Adult cottontails showed minor seasonal differences in survival, with no clear differences between males and females. Densities varied seasonally, with females having higher densities (min = 80 individuals/km2; max = 553 individuals/km2) than males (min = 56 individuals/km2; max = 337 individuals/km2).Eastern cottontails are characterized by high survival and high densities, at least when adults, in their invaded range in Italy. Although densities are comparable to those reported in North America, our analysis focused on adult cottontails only and overall densities are certainly higher. Moreover, our estimates, obtained through a capture-recapture approach, were higher than those reported in previous studies from Italy based on nocturnal spotlight censuses. Spotlight transects are likely to underestimate cottontail densities, due to nocturnal habitat selection of cottontails, which might decrease their detectability.

scholarly journals First estimates of survival and densities of invasive alien Eastern cottontail (Sylvilagus floridanus) in Italy: a capture-recapture approach

2019 ◽  
Author(s):  
Jacopo Cerri ◽  
Sandro Bertolino
Keyword(s):  
North America ◽  
Native Species ◽  
Survival Rates ◽  
Northern Italy ◽  
High Survival ◽  
Sylvilagus Floridanus ◽  
Open Population ◽  
Capture Recapture ◽  
Eastern Cottontail ◽  
Selection Of

The Eastern cottontail (Sylvilagus floridanus) has become invasive in Central and Northern Italy, where it affects prey-predator dynamics between native species. Although many different studies explored survival rates and the density of cottontails in North America, no information is available for its invasive range. Between December 2003 and October 2005, a capture-recapture scheme for Eastern cottontails was enforced on the Orba River, Italy. We fitted an open-population Cormack-Jolly-Seber model to estimate survival of adult individuals (n=258) and their density in the study area. Adult cottontails showed a constant survival (phi = 0.84 ± 0.02) across the various sessions, as well as between individuals of different sexes. Capture probabilities and densities varied seasonally, with densities ranging between 2.06 ± 1.24 and 8.00 ± 4.60 cottontails/hectare, with an average of 4.72 individuals/hectare.Eastern cottontails are characterized by high survival and high densities, in their invaded range in Italy. Although densities are comparable to those reported in North America, our analysis focused on adult cottontails only and overall densities are certainly higher. Moreover, our estimates, obtained through a capture-recapture approach, were higher than those reported in previous studies from Italy that adopted nocturnal spotlight censuses. Spotlight transects are likely to underestimate cottontail densities, due to nocturnal habitat selection of cottontails, which might decrease their detectability.

scholarly journals High frequency of social polygyny reveals little costs for females in a songbird

2022 ◽  
Vol 12 (1) ◽  
Author(s):  
Simone Santoro ◽  
Pilar Fernández-Díaz ◽  
David Canal ◽  
Carlos Camacho ◽  
László Z. Garamszegi ◽  
...  
Keyword(s):  
Environmental Conditions ◽  
Survival Rates ◽  
Central Spain ◽  
Pair Bonds ◽  
Rearing Conditions ◽  
Capture Recapture ◽  
Males And Females ◽  
The Difference ◽  
The Cost

AbstractMating system theory predicts that social polygyny—when one male forms pair bonds with two females—may evolve by female choice in species with biparental care. Females will accept a polygynous male if the benefit of mating with a male providing high-quality genes or rearing resources outweighs the cost of sharing mate assistance in parental care. Based on this rationale, we hypothesise that the population frequency of social polygyny (FSP) varies due to changes in mate sharing costs caused by changing environmental conditions. We predicted that: (1) polygamous females (i.e. mated with a polygynous male) pay a survival cost compared to monogamous females; (2) FSP would be higher in years with better rearing conditions and (3) the difference in survival rates between monogamous and polygamous females would be small following years with higher FSP. We tested these predictions using regression and multistate analyses of capture-recapture data of pied flycatchers, Ficedula hypoleuca, in central Spain collected over 26 years (1990–2016). Monogamous females had a higher mean survival rate than polygamous females (prediction 1), but there was no difference in survival between polygynous and monogamous males. In addition, FSP was positively associated with annual reproductive success (a proxy of the quality of rearing conditions—prediction 2). Finally, following years with high FSP, the survival of polygamous females was similar to that of monogamous females (prediction 3), while the chance of breeding in a polygamous state for 2 years in a row increased for both males and females. Our findings suggest that fluctuating environmental conditions may be a necessary but neglected aspect of understanding social polygyny mechanisms.

Survival of Alytes cisternasii tadpoles in stream pools: a capture-recapture study using photo-identification

2011 ◽  
Vol 32 (3) ◽  
pp. 365-374 ◽  
Author(s):  
Joana Ribeiro ◽  
Rui Rebelo
Keyword(s):  
Survival Rates ◽  
Larval Survival ◽  
Life Cycles ◽  
Life History Stage ◽  
High Survival ◽  
Amphibian Population ◽  
Photo Identification ◽  
Temporary Stream ◽  
Capture Recapture ◽  
First Time

AbstractFor amphibians with complex life cycles, the regulation of populations may occur in each life history stage and although available data stress the importance of studying amphibian population dynamics during the larval stage, most studies so far still focus only on the adult phase, due to the difficulty to estimate larval survival under field conditions. Through a two-months capture-recapture study of 646 photo-identified tadpoles of Alytes cisternasii we aimed to estimate tadpole survival in isolated temporary stream pools – their main habitat – as well as to evaluate how pool characteristics and intraspecific competition (tadpole density) affect this parameter. Photo-identification was performed with the help of the software I3S. We used the POPAN formulation of the Jolly-Seber model to estimate survival rates and population size in 9 stream pools. Tadpole density varied from ∼1 to 40 tadpoles · m–2. Tadpole weekly survival was relatively high, varying from 75 to 99% · week–1. Among-pool differences in survival were best explained by pool depth, and not by tadpole density or other pool characteristics. The lower survival estimates were obtained for the deep pools. The very high survival estimates for some pools are an indication that this type of discrete habitat may play an important role for this species. To our knowledge, this is the first time that photo-identification is used to obtain estimates for survival and density of tadpoles.

scholarly journals The role of biotic factors during plant establishment in novel communities assessed with an agent-based simulation model

2017 ◽  
Author(s):  
Janina Radny ◽  
Katrin M Meyer
Keyword(s):  
Survival Rate ◽  
Simulation Model ◽  
Native Species ◽  
Native Plants ◽  
Survival Rates ◽  
High Survival ◽  
Native Community ◽  
Establishment Success ◽  
Positive Effects ◽  
Negative Effect

Background. Establishment success of non-native species can be influenced by interactions with native competitors and novel enemies. Magnitude of interactions between species is mediated by traits, e.g. reflecting competitive strength or defence mechanisms. We combine the concepts to investigate the importance of species traits for successful establishment in a novel community exhibiting biotic resistance in the form of competition and herbivory. Methods. We developed an individual-based simulation model that tracks survival rate of non-native plants in a native community. Non-native plants are characterized by high or low values of traits relevant for interaction with competitors and herbivores. Results. Traits related to competition had a much greater impact on survival of non-native species than traits related to defence. Survival rates of strong competitors never fell below 50% while survival of weak competitors averaged about 10%. Weak competitors were also much more sensible to competitive pressures including community density, composition and asymmetry while strong competitors responded negatively to changes in competition intensity but hardly to composition or density of native community. High initial numbers of non-native individuals did decrease survival rate of strong competitors but slightly increased survival rate of weak competitors. In the current model configuration we detected only minor advantages in terms of higher survival from high defensive ability as compared to low defensive ability under enemy attack. Surprisingly, herbivory increased survival rate of species classified as weak competitors. Discussion. High survival rates of strong competitors relate to a higher chance of establishment as compared to weak competitors. However, the negative effect of high initial numbers for strong competitive non-natives indicates a self-thinning effect, probably through creation of a highly competitive milieu. For weak competitors, our model predicted increasing survival rates at high initial densities. Positive effects of high propagule pressure have been proposed in field studies and are underlined with this model. However, our model largely overestimated mortality as compared to the preceding experiment. This could be improved by implementing more sophisticated competition modes and traits reflecting tolerance and avoidance of competition by non-native plants. This would, however, be very costly in terms of parameterization. Herbivory had a very low negative effect on survival in general and an advantage of high defence was almost untraceable. However, the positive effect of herbivory on survival of weak competitors indicated that herbivory should not be neglected in estimation of establishment success of species. Although the immediate and expected effect of herbivory might be small, side effects as weakening of resident competitors might play an important role for establishment in a new community.

Differential mortality of sympatric snowshoe hares and cottontail rabbits in central Wisconsin

1993 ◽  
Vol 71 (8) ◽  
pp. 1694-1697 ◽  
Author(s):  
Lloyd B. Keith ◽  
Sara E. M. Bloomer
Keyword(s):  
Low Temperatures ◽  
Escape Behavior ◽  
Survival Rates ◽  
Differential Mortality ◽  
Interspecific Difference ◽  
High Survival ◽  
Sylvilagus Floridanus ◽  
Proximate Cause ◽  
Snowshoe Hares ◽  
Foot Loading

During 1990 and 1991 we livetrapped and radio-collared cottontail rabbits (Sylvilagus floridanus) and snowshoe hares (Lepus americanus) on five sites (three in lowland deciduous cover, two in conifer bogs) in central Wisconsin. The survival rates of these sympatric cottontails and snowshoes were equally high during snow-free periods from mid-March through October. With the onset of persistent snow cover (mean depth 20 cm) and low temperatures (mean daily minimum −14 °C) in November 1991, the 60-day survival rate of cottontails plummeted from 0.89 to 0.18 (P < 0.01) whereas snowshoe survival declined only moderately from 0.84 to 0.63 (P = 0.19). This interspecific difference reflected continued high survival of snowshoes (0.80), but not of cottontails (0.15), in the conifer bogs. Predation, primarily by coyotes, was the proximate cause of 37 of 39 rabbit and hare deaths, and was thus the overwhelming determinant of survival. We speculate that where persistent snow and low temperatures characterize winter, the cottontail's greater foot loading, brown coloration, and escape behavior markedly increase its vulnerability to predators. This probably explains the absence of cottontails from the forests of northern Wisconsin.

scholarly journals Juvenile and Adult Survival in the Sociable Weaver (Philetairus Socius), A Southern-Temperate Colonial Cooperative Breeder in Africa

The Auk ◽  
2004 ◽  
Vol 121 (4) ◽  
pp. 1199-1207
Author(s):  
Rita Covas ◽  
Charles R. Brown ◽  
Mark D. Anderson ◽  
Mary Bomberger Brown
Keyword(s):  
Survival Rates ◽  
Adult Survival ◽  
Easy Access ◽  
High Survival ◽  
Capture Recapture ◽  
Sociable Weavers ◽  
Philetairus Socius ◽  
Similar Survival ◽  
Survival Patterns ◽  
Access To Food

Abstract We used capture-recapture analyses to describe juvenile and adult survival from 1993 to 2001 in a population of Sociable Weavers (Philetairus socius), a colonial, cooperatively breeding passerine of southern Africa. We examined temporal variation in survival and the role that the breeding season's length and environmental factors play in determining survival patterns in the population. Annual survival probability (mean ± SE) was 0.66 ± 0.02. In contrast to most passerines, juveniles and adults had similar survival probabilities; survival rates did not vary significantly between years. We found no relationship among temperature, rainfall, and survival. Relatively high survival rates in Sociable Weavers probably result from a benign climate and easy access to food in winter. Juvenile survival may also be enhanced by prolonged parental care and delayed dispersal.

scholarly journals Impacts of experimental defoliation on native and invasive saplings: are native species more resilient to canopy disturbance?

2020 ◽  
Vol 40 (7) ◽  
pp. 969-979
Author(s):  
Elise D Hinman ◽  
Jason D Fridley
Keyword(s):  
Invasive Species ◽  
North America ◽  
Native Species ◽  
Radial Growth ◽  
Survival Rates ◽  
Growth Strategy ◽  
Extreme Weather Events ◽  
Leaf Production ◽  
Growing Seasons ◽  
Light Gradient

Abstract Many non-native, invasive woody species in mesic forests of North America are both shade tolerant and more productive than their native counterparts, but their ability to tolerate disturbances remains unclear. In particular, complete defoliation associated with herbivory and extreme weather events may have larger impacts on invaders if natives maintain greater resource reserves to support regrowth. On the other hand, invaders may be more resilient to partial defoliation by means of upregulation of photosynthesis or may be better able to take advantage of canopy gaps to support refoliation. Across a light gradient, we measured radial growth, new leaf production, non-structural carbohydrates (NSCs), chlorophyll content and survival in response to varying levels of defoliation in saplings of two native and two invasive species that commonly co-occur in deciduous forests of Eastern North America. Individuals were subjected to one of the four leaf removal treatments: no-defoliation controls, 50% defoliation over three growing seasons, 100% defoliation over one growing season and 100% defoliation over two growing seasons. Contrary to our hypothesis, native and invasive species generally did not differ in defoliation responses, although invasive species experienced more pronounced decreases in leaf chlorophyll following full defoliation and native species’ survival was more dependent on light availability. Radial growth progressively decreased with increasing defoliation intensity, and refoliation mass was largely a function of sapling size. Survival rates for half-defoliated saplings did not differ from controls (90% of saplings survived), but survival rates in fully defoliated individuals over one and two growing seasons were reduced to 45 and 15%, respectively. Surviving defoliated saplings generally maintained control NSC concentrations. Under high light, chlorophyll concentrations were higher in half-defoliated saplings compared with controls, which may suggest photosynthetic upregulation. Our results indicate that native and invasive species respond similarly to defoliation, despite the generally faster growth strategy of invaders.

scholarly journals Movements and capture-recapture data analysis of the vesper rat (Nyctomys sumichrasti : Rodentia, Muridae) in a tropical forest in northeastern Oaxaca, Mexico.

2010 ◽  
Vol 26 (3) ◽  
Author(s):  
Martín Pérez-Lustre ◽  
Antonio Santos-Moreno
Keyword(s):  
Data Analysis ◽  
Standard Deviation ◽  
Population Size ◽  
Extreme Values ◽  
Average Distance ◽  
Survival Rates ◽  
Capture Probability ◽  
Complete Study ◽  
Capture Recapture ◽  
Males And Females

In order to explain the population demography of the Vesper Rat (Nyctomys sumichrasti) and with regarding to an estimate of population size and survival rates, as well as possible differences in the movements distances between males and females, we analyzed capture-recapture data of this species from a trapping effort of 455 trap-nights and a total of 157 captures of 36 individuals which were livetraped at 3 trap heights: 3-9 m above ground (low canopy), 9-15 m (medium canopy) and the highest part of the canopy, 15-21.5 m. Due to differences between age categories in sample size, the analysis of capture-recapture histories was restricted to adult individuals. The sample of 29 adult individuals included 12 females (8 singletons and 4 captured in the complete study) and 17 males (5 singletons and 12 captured in the complete study); which represents a sex-ratio of 1:1.41, which did not differ statistically from 1:1. The capture-recapture histories were analyzed using the Cormack-Jolly-Seber model, where the best model maintains the survival constant and equal between sexes, and capture probability is constant through time, but differs between sexes. The survival probability was 0.8287, while the capture probability was 0.874 for males and 0.5733 for females. Estimated population size included 19 males and 21 females. The average distance travelled by females was 34.86 m (standard deviation 5.92) with extreme values of 20.1 to 60.32, whereas for males was 35.42 m (standard deviation 18.27), with extreme values of 10.3 to 75.1 m.

First assessment of the potential introduction by hunters of eastern cottontail rabbits (Sylvilagus floridanus) in Spain

2018 ◽  
Vol 45 (7) ◽  
pp. 571 ◽  
Author(s):  
M. Delibes-Mateos ◽  
F. Castro ◽  
V. Piorno ◽  
E. Ramírez ◽  
J. A. Blanco-Aguiar ◽  
...  
Keyword(s):  
Native Species ◽  
Propagule Pressure ◽  
Population Control ◽  
Climatic Conditions ◽  
European Rabbit ◽  
Sylvilagus Floridanus ◽  
Monitoring Networks ◽  
Game Species ◽  
Eastern Cottontail ◽  
Rate Of Success

Context Humans have introduced lagomorph species in areas outside their native ranges for their meat, fur or value as game species. Assessing the rate of success of lagomorph introductions is vital to address the ecological damage they may cause. Cases of failed lagomorph introductions in apparently suitable areas may also shed light on mechanisms that may deter invasion, which are useful in developing strategies for population control. In Spain, it has been suggested that hunters introduced the non-native eastern cottontail (Sylvilagus floridanus) to compensate for the recent drastic declines of the native European rabbit (Oryctolagus cuniculus). Aims Our main goals were to investigate (1) whether Sylvilagus rabbits have indeed been introduced by hunters across Spain, and (2) whether the species has become established in Spanish ecosystems. Methods We interviewed 311 hunters or naturalists across Spain. The questionnaires inquired about the characteristics of game management in each locality, including the frequency of rabbit restocking, and particularly whether Sylvilagus rabbits had been released in the surveyed localities. In addition, we sampled 192 rabbit populations (n=3974 individuals) across Spain by using molecular analysis to determine whether Sylvilagus rabbits were present in these areas. Key results Our interview results suggest that Sylvilagus rabbits may have been released in 6% of the 311 localities surveyed. However, molecular analyses failed to confirm their persistence, because all samples belonged to O. cuniculus. Conclusions We infer that Sylvilagus rabbits failed to establish themselves in Spain, although interviewees reported their introduction. Several reasons may explain the unsuccessful establishment of this species, such as a low propagule pressure, competition with native species, predation, inability to cope with local pathogens and unsuitable climatic conditions. Implications The risk of future introductions of non-native game species can be reduced through the implementation of stricter regulations of animal releases into the wild. Long-term monitoring networks should be developed to help identify non-native game species before they become established and spread to neighbouring areas, thereby preventing any ecological or economic impacts these species may cause.

scholarly journals The role of biotic factors during plant establishment in novel communities assessed with an agent-based simulation model

2017 ◽  
Author(s):  
Janina Radny ◽  
Katrin M Meyer
Keyword(s):  
Survival Rate ◽  
Simulation Model ◽  
Native Species ◽  
Native Plants ◽  
Survival Rates ◽  
High Survival ◽  
Native Community ◽  
Establishment Success ◽  
Positive Effects ◽  
Negative Effect

Background. Establishment success of non-native species can be influenced by interactions with native competitors and novel enemies. Magnitude of interactions between species is mediated by traits, e.g. reflecting competitive strength or defence mechanisms. We combine the concepts to investigate the importance of species traits for successful establishment in a novel community exhibiting biotic resistance in the form of competition and herbivory. Methods. We developed an individual-based simulation model that tracks survival rate of non-native plants in a native community. Non-native plants are characterized by high or low values of traits relevant for interaction with competitors and herbivores. Results. Traits related to competition had a much greater impact on survival of non-native species than traits related to defence. Survival rates of strong competitors never fell below 50% while survival of weak competitors averaged about 10%. Weak competitors were also much more sensible to competitive pressures including community density, composition and asymmetry while strong competitors responded negatively to changes in competition intensity but hardly to composition or density of native community. High initial numbers of non-native individuals did decrease survival rate of strong competitors but slightly increased survival rate of weak competitors. In the current model configuration we detected only minor advantages in terms of higher survival from high defensive ability as compared to low defensive ability under enemy attack. Surprisingly, herbivory increased survival rate of species classified as weak competitors. Discussion. High survival rates of strong competitors relate to a higher chance of establishment as compared to weak competitors. However, the negative effect of high initial numbers for strong competitive non-natives indicates a self-thinning effect, probably through creation of a highly competitive milieu. For weak competitors, our model predicted increasing survival rates at high initial densities. Positive effects of high propagule pressure have been proposed in field studies and are underlined with this model. However, our model largely overestimated mortality as compared to the preceding experiment. This could be improved by implementing more sophisticated competition modes and traits reflecting tolerance and avoidance of competition by non-native plants. This would, however, be very costly in terms of parameterization. Herbivory had a very low negative effect on survival in general and an advantage of high defence was almost untraceable. However, the positive effect of herbivory on survival of weak competitors indicated that herbivory should not be neglected in estimation of establishment success of species. Although the immediate and expected effect of herbivory might be small, side effects as weakening of resident competitors might play an important role for establishment in a new community.

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