scholarly journals Experimental removal of introduced slider turtles offers new insight into competition with a native, threatened turtle

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e7444 ◽  
Author(s):  
Max R. Lambert ◽  
Jennifer M. McKenzie ◽  
Robyn M. Screen ◽  
Adam G. Clause ◽  
Benjamin B. Johnson ◽  
...  
Keyword(s):  
Native Species ◽  
Field Experiments ◽  
Slider Turtle ◽  
Species Of Conservation Concern ◽  
Ecological Resources ◽  
Mesocosm Experiments ◽  
In The Wild ◽  
Western Pond Turtle ◽  
Negative Impacts ◽  
Conservation Concern

The red-eared slider turtle (Trachemys scripta elegans; RES) is often considered one of the world’s most invasive species. Results from laboratory and mesocosm experiments suggest that introduced RES outcompete native turtles for key ecological resources, but such experiments can overestimate the strength of competition. We report on the first field experiment with a wild turtle community, involving introduced RES and a declining native species of conservation concern, the western pond turtle (Emys marmorata; WPT). Using a before/after experimental design, we show that after removing most of an introduced RES population, the remaining RES dramatically shifted their spatial basking distribution in a manner consistent with strong intraspecific competition. WPT also altered their spatial basking distribution after the RES removal, but in ways inconsistent with strong interspecific competition. However, we documented reduced levels of WPT basking post-removal, which may reflect a behavioral shift attributable to the lower density of the turtle community. WPT body condition also increased after we removed RES, consistent with either indirect or direct competition between WPT and RES and providing the first evidence that RES can compete with a native turtle in the wild. We conclude that the negative impacts on WPT basking by RES in natural contexts are more limited than suggested by experiments with captive turtles, although wild WPT do appear to compete for food with introduced RES. Our results highlight the importance of manipulative field experiments when studying biological invasions, and the potential value of RES removal as a management strategy for WPT.

scholarly journals Large-scale experimental removal of non-native slider turtles has unexpected consequences on basking behavior for both conspecifics and a native, threatened turtle

2018 ◽  
Author(s):  
Max R. Lambert ◽  
Jennifer M. McKenzie ◽  
Robyn M. Screen ◽  
Adam G. Clause ◽  
Benjamin J. Johnson ◽  
...  
Keyword(s):  
Interspecific Competition ◽  
Native Species ◽  
Large Scale ◽  
Slider Turtle ◽  
Central United States ◽  
Freshwater Habitats ◽  
Mesocosm Experiments ◽  
In The Wild ◽  
Species Being ◽  
The U.S

AbstractThe red-eared slider turtle (Trachemys scripta elegans; RES) is one of the world’s most invasive species. Native to the central United States, RES are now widely established in freshwater habitats across the globe, largely due to release of unwanted pets. Laboratory and mesocosm experiments suggest that introduced RES are competitively dominant to native turtles, but such competition remains untested in the wild. Here, we experimentally removed introduced RES to test whether they compete for critical basking habitat with native, threatened western pond turtles (Emys marmorata; WPT), a species being considered for listing under the U.S. Endangered Species Act. Following removal, we found that both the remaining RES as well as WPT altered their basking distribution but in a manner inconsistent with strong interspecific competition. However, these findings suggest strong intraspecific competition for basking sites amongst RES and that interspecific competition between WPT and introduced RES likely occurs at higher RES densities. Our works suggests RES influence the behavior of native species in the wild and indicates that RES removal may be most beneficial at high RES densities. This experiment highlights the importance of considering experimental venue when evaluating competition between native and non-native species and should encourage conservation biologists to treat removal efforts as experiments.

scholarly journals Intrinsic Prey Preference and Selection of the Giant Gartersnake: A Threatened Predator in a Nonnative Prey-Dominated Community

2020 ◽  
Vol 11 (1) ◽  
pp. 164-173
Author(s):  
Julia S.M. Ersan ◽  
Brian J. Halstead ◽  
Erica L. Wildy ◽  
Michael L. Casazza ◽  
Glenn D. Wylie
Keyword(s):  
Exotic Species ◽  
Native Species ◽  
Prey Selection ◽  
Central Valley ◽  
Prey Preference ◽  
Live Prey ◽  
Species Of Conservation Concern ◽  
Conservation Concern ◽  
Behavioral Trials ◽  
Selection Of

Abstract The introduction of exotic species into an environment can introduce great change in the trophic dynamics of native species. This is of even greater concern if the native species is of conservation concern. The giant gartersnake, Thamnophis gigas, an endemic predator of the Central Valley of California and a species of conservation concern at the state and federal levels, has declined as a result of conversion of its once vast wetland habitat to agriculture. Another anthropogenic factor contributing to this snake's changing ecology is the introduction of nonnative prey into the species' habitats. These introductions have resulted in a prey community that is almost completely composed of exotic species and have potential for considerable effects. In order to assess prey preference and selection we performed three sets of behavioral trials on naïve neonates. We examined 1) neonate prey preference in response to olfactory cues of prepared prey extracts, 2) neonate consumption of different live prey items presented simultaneously; and 3) terrestrial feeding behavior and/or latency to successful attack. Results from the olfactory study suggest that native Sierran treefrogs, Pseudacris sierra, are preferred by neonates. Results from consumption trials suggest that neonates are more likely to select frog species than fish species. This is the first study that we are aware of that examines prey selection of this threatened species and serves to inform its conservation and management.

scholarly journals Loss of Predator Discrimination by Critically Endangered Vancouver Island Marmots Within Five Generations of Breeding for Release

2021 ◽  
Vol 2 ◽  
Author(s):  
Graham P. Dixon-MacCallum ◽  
Johnathan L. Rich ◽  
Natasha Lloyd ◽  
Daniel T. Blumstein ◽  
Axel Moehrenschlager
Keyword(s):  
Vancouver Island ◽  
Predator Recognition ◽  
Critically Endangered ◽  
Species Of Conservation Concern ◽  
Mammalian Predators ◽  
In Captivity ◽  
Two Generations ◽  
In The Wild ◽  
Conservation Concern ◽  
Changes Over Time

Conservation translocations, which involve the intentional movement and release of organisms for conservation benefit, are increasingly required to recover species of conservation concern. In order to maximize post-release survival, and to accomplish conservation translocation objectives, animals must exhibit behaviors that facilitate survival in the wild. The Vancouver Island marmot (Marmota vancouverensis) is a critically endangered endemic in Canada which has been captive-bred for 24 years for reintroductions and reinforcements that have increased the wild population from ~30 to more than 200 individuals. Despite this success many marmots are killed by predators after release and predation represents a major hurdle to full marmot recovery. To better understand if captive-bred marmots are prepared for the novel environment into which they will be released, and to determine whether such suitability changes over time, we presented taxidermy mounts of mammalian predators and non-predators to marmots that were wild-caught, and captive born for between one and five generations. We also examined mortality of offspring from marmots we tested that had been released to the wild. A minimum of 43% of offspring were killed by predators in the wild over 17 years, most by cougars. Marmots in captivity generally responded to taxidermy mounts by decreasing foraging and increasing vigilance, and overall responded more strongly to predators than non-predators, especially wolves. However, marmots in captivity for more than two generations lacked discrimination between cougars, non-predators, and controls, suggesting a rapid loss of predator recognition. This study was only possible because predator-recognition trials were initiated early in the conservation translocation program, and could then be repeated after a number of generations. The finding that changes occurred relatively rapidly (within five generations during which changes in genetic diversity were negligible) suggests that behavioral suitability may deteriorate more rapidly than genetics would suggest. Strategies addressing potential behavior loss should be considered, including sourcing additional wild individuals or pre-release training of captive-born individuals. Subsequently, post-release survival should be monitored to determine the efficacy of behavior-optimization strategies.

scholarly journals Parentage Assignment Reveals Multiple Paternity in the Critically-Endangered Guatemalan Beaded Lizard (Heloderma Charlesbogerti)

2021 ◽  
Author(s):  
Brenna A Levine ◽  
Robert Hill ◽  
Joseph Mendelson ◽  
Warren Booth
Keyword(s):  
Genetic Diversity ◽  
Mating System ◽  
Prediction Models ◽  
Multiple Paternity ◽  
Parentage Analysis ◽  
Multiple Sexual Partners ◽  
Species Of Conservation Concern ◽  
In The Wild ◽  
Genetic Mating System ◽  
Conservation Concern

Abstract Within captive management programs for species of conservation concern, understanding the genetic mating system is of fundamental importance, given its role in generating and maintaining genetic diversity and promoting opportunities for sperm competition. If a goal of a conservation program is reintroduction, knowledge of the mating system may also inform prediction models aimed at understanding how genetic diversity may be spatially organized, thus informing decisions regarding where and which individuals should be released in order to maximize genetic diversity in the wild population. Within captive populations, such information may also influence how animals are maintained in order to promote natural behaviors. Here we investigate the genetic mating system of the Guatemalan beaded lizard, Heloderma charlesbogerti, a member of a genus lacking such information. A group of adult male and female H. charlesbogerti were co-habited for five years during the species perceived breeding season. Through genomic parentage analysis, 50% of clutches comprising multiple offspring were found to result from polyandry, with up to three males siring offspring within single clutches. Furthermore, males were found to be polygamous both within and across seasons, and females would exhibit promiscuity across seasons. As such, within this captive environment, where opportunities existed for mating with multiple sexual partners, the genetic mating system was found to be highly promiscuous, with multiple paternity common within clutches. These findings are novel for the family Helodermatidae, and the results have broader implications about how reproductive opportunities should be managed within captive conservation programs.

Mutual dilution of infection by an introduced parasite in native and invasive stream fishes across Hawaii

Parasitology ◽  
2016 ◽  
Vol 143 (12) ◽  
pp. 1605-1614 ◽  
Author(s):  
RODERICK B. GAGNE ◽  
DAVID C. HEINS ◽  
PETER B. MCINTYRE ◽  
JAMES F. GILLIAM ◽  
MICHAEL J. BLUM
Keyword(s):  
Water Quality ◽  
Native Species ◽  
Host Density ◽  
Dilution Effect ◽  
Urban Land Use ◽  
Parasite Abundance ◽  
Species Of Conservation Concern ◽  
Awaous Stamineus ◽  
Conservation Concern ◽  
Camallanus Cotti

SUMMARYThe presence of introduced hosts can increase or decrease infections of co-introduced parasites in native species of conservation concern. In this study, we compared parasite abundance, intensity, and prevalence between nativeAwaous stamineusand introduced poeciliid fishes by a co-introduced nematode parasite (Camallanus cotti) in 42 watersheds across the Hawaiian Islands. We found that parasite abundance, intensity and prevalence were greater in native than introduced hosts. Parasite abundance, intensity and prevalence withinA. stamineusvaried between years, which largely reflected a transient spike in infection in three remote watersheds on Molokai. At each site we measured host factors (length, density of native host, density of introduced host) and environmental factors (per cent agricultural and urban land use, water chemistry, watershed area and precipitation) hypothesized to influenceC. cottiabundance, intensity and prevalence. Factors associated with parasitism differed between native and introduced hosts. Notably, parasitism of native hosts was higher in streams with lower water quality, whereas parasitism of introduced hosts was lower in streams with lower water quality. We also found that parasite burdens were lower in both native and introduced hosts when coincident. Evidence of a mutual dilution effect indicates that introduced hosts can ameliorate parasitism of native fishes by co-introduced parasites, which raises questions about the value of remediation actions, such as the removal of introduced hosts, in stemming the rise of infectious disease in species of conservation concern.

Reducing the primary exposure risk of Henderson crakes (Zapornia atra) during aerial broadcast eradication by selecting appropriate bait colour

2016 ◽  
Vol 43 (4) ◽  
pp. 298 ◽  
Author(s):  
Steffen Oppel ◽  
Jennifer L. Lavers ◽  
Alexander L. Bond ◽  
Gavin Harrison
Keyword(s):  
Mixed Models ◽  
Native Species ◽  
Exposure Risk ◽  
Island Endemic ◽  
Invasive Predators ◽  
Species Of Conservation Concern ◽  
In Captivity ◽  
Specific Variation ◽  
Conservation Concern ◽  
Native Invasive

Context Operations to eradicate non-native invasive predators from islands frequently put native species at risk of consuming harmful substances, such as poison bait. The incorporation of certain colours in poison-bait pellets may reduce the risk of bait consumption and, therefore, non-target mortality. Previous work indicated that birds generally avoid blue or green colours; however, there is substantial inter-specific variation in this preference, and more experimental work on species of conservation concern is needed. Aims We tested whether a globally threatened island endemic, the Henderson crake (Zapornia atra), which suffered substantial mortality during a rat-eradication attempt on Henderson Island in 2011, would consume fewer blue than green pellets, which were used during the previous eradication attempt. Methods We held 22 Henderson crakes in captivity and provided them with either blue or green non-toxic pellets for 5 days in June and July 2015. We measured consumption and used linear mixed models to evaluate whether bait colour influenced consumption. Key results Henderson crakes did not consume any dry pellets, and all trials were conducted with wet bait pellets. We found slightly lower consumption of blue pellets than green pellets, and substantial variation among individuals. Females (n = 17) consumed 24% less blue than green bait, whereas males (n = 5) consumed 77% less blue than green bait. Conclusion Henderson crakes are unlikely to consume dry pellets, and will likely consume fewer blue than green bait pellets. Implications We recommend that any future rat eradication on Henderson Island considers using blue rather than green baits and targets dry weather to reduce the risk of Henderson crakes consuming toxic rodenticide bait pellets.

scholarly journals Between approval and disapproval: Citizens’ views on the invasive tree Ailanthus altissima and its management

NeoBiota ◽  
2021 ◽  
Vol 66 ◽  
pp. 1-30
Author(s):  
Ingo Kowarik ◽  
Tanja M. Straka ◽  
Mario Lehmann ◽  
Rafael Studnitzky ◽  
Leonie K. Fischer
Keyword(s):  
Native Species ◽  
Management Strategies ◽  
Complete Removal ◽  
Green Spaces ◽  
Ailanthus Altissima ◽  
Widespread Species ◽  
Urban Green Spaces ◽  
Management Measures ◽  
Negative Impacts ◽  
Conservation Concern

While cities are invasion hotspots, the view of urban residents on non-native species is critically understudied – an important knowledge gap since strategies on biological invasions could gain power by integrating human values, attitudes and perceptions. How citizens perceive the non-native tree Ailanthus altissima (tree of heaven) is unknown despite its abundance in many cities globally and its classification as invasive in many countries. In a quantitative survey with closed questions, we analysed (i) whether residents of Berlin, Germany knew the widespread species, (ii) how they perceived it in different urban situations, (iii) how they accepted different management strategies of it, and (iv) how the sociodemographic background of respondents predicted their preference and acceptability ratings. In total, we surveyed 196 respondents. Most respondents recognized the tree in a photograph, but few provided its correct name. Citizens’ preferences differed significantly among four urban contexts in which the species was shown, with prevailing approval for trees as a component of designed green spaces and less pronounced preferences for wild-grown trees in other urban spaces. When respondents were asked to indicate how the tree should be managed (three options), we found the most support for removal in problematic cases (‘adaptive on-site’ strategy); some support was found for the ‘leave alone’ strategy and least support for the ‘complete removal’ management strategy. Practitioners with expertise in urban landscaping were more critical of Ailanthus than laypeople. Ordinal logistic regression analyses showed that respondents with a ‘close to nature’ behaviour and attitude had a more positive view on Ailanthus and expressed more support for ‘leave alone’ management. Results demonstrate the importance of citizens’ context dependent views about a widespread invasive species, spanning from approval to disapproval in different situations. We conclude that urban management strategies concerning Ailanthus would gain support from citizens when combining multiple approaches: (i) to control the species in case of realized negative impacts; (ii) to prevent the invasion of the species in areas of conservation concern; and (iii) to develop novel approaches of integrating wild Ailanthus trees into urban green spaces. These insights could support management measures that need to be established due to the EU-Regulation on Invasive Alien Species.

scholarly journals No correlation between neonatal fitness and heterozygosity in a reintroduced population of Père David’s deer

2013 ◽  
Vol 59 (2) ◽  
pp. 249-256 ◽  
Author(s):  
Yan Zeng ◽  
Chunwang Li ◽  
Linyuan Zhang ◽  
Zhenyu Zhong ◽  
Zhigang Jiang
Keyword(s):  
Birth Weight ◽  
Neonatal Mortality ◽  
Microsatellite Loci ◽  
Mammal Species ◽  
Species Of Conservation Concern ◽  
In Captivity ◽  
In The Wild ◽  
Père David’S Deer ◽  
Genetic Bottlenecks ◽  
Conservation Concern

Abstract Considering the severe impacts of genetic bottlenecks and small numbers of founders in populations of reintroduced animals, it is necessary to study inbreeding and its effect on fitness in species of conservation concern. Père David’s deer is one of few large mammal species extinct in the wild but safely preserved in captivity. Its specific background gives us the opportunity to study the relationships between heterozygosity and neonatal fitness in relocated populations. We employed five microsatellite loci to explore heterozygosity-fitness correlations in a population of Père David’s deer at the Beijing Milu Ecological Research Center. We observed associations between microsatellite-based variables sMLH, IR, MD2 and HL, and two components of fitness expressed early in life (birth weight and the neonatal mortality of 123 Père David’s deer calves born over six consecutive years). We found that neonatal mortality was 19.1% ± 7.6%, not higher than the 19% or 18% reported in other ungulates. The heterozygosity of calves was not associated with neonatal mortality, nor birth weight. Our study implies that low genetic variability of microsatellite loci has no overt effect on birth weight and neonatal mortality in reintroduced populations of Père David’s deer.

Climatic Variables Differentially Influence Neotropical Plant Species of Conservation Concern

2021 ◽  
pp. 1-16
Author(s):  
Pablo Antúnez ◽  
Christian Wehenkel ◽  
Collins Byobona Kukunda ◽  
José Ciro Hernández-Díaz
Keyword(s):  
Plant Species ◽  
Climatic Variables ◽  
Species Of Conservation Concern ◽  
Conservation Concern

scholarly journals Nesting, Sex Ratio and Natural Enemies of the Giant Resin Bee in Relation to Native Species in Europe

Insects ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 545
Author(s):  
Sara Straffon Díaz ◽  
Luca Carisio ◽  
Aulo Manino ◽  
Paolo Biella ◽  
Marco Porporato
Keyword(s):  
Sex Ratio ◽  
Natural Enemies ◽  
Native Species ◽  
Wild Bees ◽  
Trap Nests ◽  
Native Bee ◽  
New Locations ◽  
Negative Impacts ◽  
Set Up ◽  
North Western

Megachile sculpturalis (Smith, 1853) is the first exotic bee species in Europe. Its remarkably fast expansion across this continent is leading to a growing concern on the extent of negative impacts to the native fauna. To evaluate the interactions of exotic bees with local wild bees, we set up trap nests for above-ground nesting bees on a semi-urban area of north-western Italy. We aimed to investigate the interaction in artificial traps between the exotic and native wild bees and to assess offspring traits accounting for exotic bee fitness: progeny sex ratio and incidence of natural enemies. We found that the tunnels occupied by exotic bees were already cohabited by O. cornuta, and thus the cells of later nesting alien bees may block the native bee emergence for the next year. The progeny sex ratio of M. sculpturalis was strongly unbalanced toward males, indicating a temporary adverse population trend in the local invaded area. In addition, we documented the presence of three native natural enemies affecting the brood of the exotic bee. Our results bring out new insights on how the M. sculpturalis indirectly competes with native species and on its performance in new locations.

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