Habitat and History Influence Abundance of Bog Turtles

Conservation of rare and endangered species requires assessment of factors that influence the current habitat associations of a species and the role of past habitat degradation in limiting occupancy or abundance. The objective of our 2011–2014 study was to determine how habitat characteristics and wetland history can predict occupancy and abundance patterns of bog turtles (Glyptemys muhlenbergii) at the fringe of their range in the southeastern United States. We used a hurdle model to examine occupancy and abundance patterns while addressing problems associated with zero-inflated data. Occupancy patterns were weakly related to percent of the wetland containing emergent vegetation, whereas abundance patterns were predicted by the percent silt in the wetland substrate, percent forest cover, amount of habitat degradation, and recovery time since past habitat degradation. The effect of historical habitat degradation on abundance rather than occupancy patterns has rarely been documented and its effect is rarely studied in vertebrate populations. Identification of predictors of occupancy and abundance patterns will aid discovery of new populations of bog turtles and improve management of occupied wetlands. © 2019 The Wildlife Society.     

仿野生鳖卵的磷脂及粗蛋白含量测定

仿野生鳖卵内容物冻干粉收率为 30 .6 1% ,它的粗蛋白质及磷脂含量分别为 5 0 .0 1%和 12 .74 %。TLC分析结果表明仿野生鳖卵含有 5种磷脂成份 ,而鹌鹑卵及猪脑仅含有 3种磷脂     

Effect of Incubation Temperature on the Somatic Development of the Snail-Eating Turtle Malayemys macrocephala

The rising average global temperature can lead to changes both in the physical and biological environments and affect the survival of organisms. Freshwater turtles are considered to be susceptible species since their development is dependent on incubation temperature. In Thailand, although several species of freshwater turtle are present, the extent of their susceptibility to temperature change is unknown due to the lack of information on their developmental patterns. This research, therefore, is aimed at examining the effects of temperature on somatic development in Malayemys macrocephala, a native species and the most common freshwater turtle in Thailand. Turtle eggs were collected from rice fields in the central part of Thailand during December 2011 to February 2012 inclusive. Eggs （237-238 per condition） were incubated in microprocessor-controlled incubators at three different temperatures （26 ℃, 29℃ and 32℃） with a relative humidity in excess of 80%. Each week, until the remaining eggs hatched, eggs were randomly selected, removed and dissected to reveal the developing embryo to screen for developmental stage and any abnormalities. The incubation period （lay to hatch） was not significantly different among the three temperatures （115 ±11.3 d, 115 ±20.3 d and 109±17.8 d, respectively）, but the growth patterns, as indicated by the stages of development and carapace lengths, were significantly different. At a high temperature （32℃）, turtle embryos showed a significantly faster growth rate than at the intermediate and low temperatures （29 ℃and 26 ℃）, but had a significantly （over 3.3-fold） higher incidence of developmental abnormalities （especially deformed bodies） than at the lower temperatures. Overall, the results indicate that incubation temperature is an important variable affecting the somatic development of this tropical freshwater turtle species, whilst abnormalities in the embryonic body may be a sensitive indicator of extreme thermal stress.     

Survival and recruitment of seedlings and suckers of trees and shrubs of the Australian arid zone following habitat management and the outbreak of Rabbit Calicivirus Disease (RCD)

Abstract Recruitment in many shrub and tree species in arid Australia is limited by domestic and feral animal grazing. The outbreak of Rabbit Calicivirus Disease (RCD or RHD) in late 1995 at Kinchega National Park (NP) in arid western NSW, Australia, coincided with intensified warren ripping and other rabbit (Oryctolagus cuniculus) control efforts. We monitored changes in rabbit numbers in response to these factors using spotlight counts and dung‐pellet counts. Rabbit populations declined initially, and were low for the remainder of the study. To assess the impact of rabbit control on vegetation, we examined whether recruitment of seedlings or vegetative suckers was occurring at Kinchega NP, following the arrival of RCD; how long such recruits were likely to survive under current grazing pressures; and whether the magnitude of current seedling and vegetative sucker recruitment and survival is greater than available data prior to RCD and extensive warren control. We followed the survival of individual seedlings and newly emerged suckers of six shrub or tree species, most of which are considered to be at risk of local decline. Three levels of caging were used to exclude all mammalian grazers; all mammalian grazers except rabbits; and no mammalian grazers. Pooled cohorts of seedlings and suckers were analysed using failure‐time analyses. During the course of the study, suckering was observed in four species (Acacia carneorum, Alectryon oleifolius, Casuarina pauper and Santalum acuminatum), with seedlings observed in the other two species (Dodonaea viscosa and Acacia ligulata). Survival of suckers of some species was slightly greater than pre‐RCD estimates, but in general, a pattern of little or nil recruitment is likely in suckers exposed to rabbits or to all grazing mammals. Seedling survival was particularly low regardless of the level of exclusion, largely due to desiccation. Reduction of grazing impacts may only allow recruitment into populations of species reliant on seedlings under more favourable climatic circumstances than experienced in this study, while the probability of successful recruitment into populations of suckering species in western NSW continues to be low even at very low rabbit densities.     

Effects of Zoospore Aggregation and Substrate Rugosity on Kelp Recruitment Success

Successful kelp recruitment is important for kelp population persistence and associated kelp forest communities. The proximity of settled kelp zoospores is a known requirement for successful kelp recruitment and proximity can be increased as zoospores aggregate. Substrate rugosity can also be an important factor affecting macroalgal settlement and recruitment in wave‐swept areas, and may affect kelp recruitment by aggregating zoospores. In this study, kelp zoospores were cultured at different levels of small‐scale aggregation and kelp recruitment was quantified. Sporophyte production significantly increased as zoospores became more aggregated indicating that processes that aggregate kelp zoospores have the potential to enhance kelp recruitment. A 13‐month field experiment demonstrated differential kelp recruitment onto settlement plates that mimicked surface rugosities of two common rock types within Stillwater Cove, Carmel Bay in central California (Carmelo Formation sandstone and Santa Lucia granodiorite). Significantly more kelp recruited to molds mimicking granodiorite over the yearlong study (granodiorite = 2.7 recruits ± SE 0.50, sandstone = 1.2 recruits ± SE 0.51). There was a significant difference in recruitment between seasons and this variability was due to the fact that spring had the highest average number of kelp recruits per mold. However, the interaction between substrate and season was not significant. This study emphasizes the importance of kelp zoospore aggregation on kelp recruitment and demonstrates that small‐scale rugosity affects kelp recruitment.     

Amino Acid Sequence and Activity of Green Turtle (Chelonia mydas) Lysozyme

Green turtle lysozyme purified from egg white was sequenced and analyzed its activity. Lysozyme was reduced and pyridylethylated or carboxymethylated to digest with trypsin, chymotrypsin and V8 protease. The peptides yielded were purified by RP-HPLC and sequenced. Every trypsin peptide was overlapped by chymotrypsin peptides and V8 protease peptides. This lysozyme is composed of 130 amino acids including an insertion of a Gly residue between 47 and 48 residues when compared with chicken lysozyme. The amino acid substitutions were found at subsites E and F. Namely Phe34, Arg45, Thr47, and Arg114 were replaced by Tyr, Tyr, Pro, and Asn, respectively. The time course using N-acetylglucosamine pentamer as a substrate showed a reduction of the rate constant of glycosidic cleavage and transglycosylation and increase of binding free energy for subsite E, which proved the contribution of amino acids mentioned above for substrate binding at subsites E and F.     

Urban flight: understanding individual and population-level responses of Nearctic-Neotropical migratory birds to urbanization

1. Despite the fact that studies of urban ecology have become commonplace in the literature, ecologists still lack empirical evidence of the underlying mechanisms responsible for relationships between urbanization and animal community structure. In an effort to understand the processes that govern an apparent avoidance of urban landscapes by many Nearctic-Neotropical migratory birds, we examined population- and individual-level responses of the Acadian flycatcher (Empidonax virescens) to urbanization within the landscapes surrounding 35 riparian forest stands in Ohio, USA. 2. From May to August 2001-06 we surveyed birds, banded 175 territorial flycatchers to estimate both condition and survival, tracked nest initiation dates, monitored success of 387 nests and estimated annual reproductive productivity of 163 breeding pairs. 3. Neither apparent annual survival of males (phi = 0.53 +/- 0.056 SE) nor females (phi = 0.23 +/- 0.064 SE) was related to the amount of urban development within the landscape. Similarly, daily survival rates of nests, which ranged from 0.92 to 0.98 across sites, was not associated significantly with urbanization. In contrast, reproductive productivity was related negatively to the amount of urbanization surrounding riparian forests, perhaps due in part to the greater incidence of brood parasitism and fewer numbers of nesting attempts made by pairs in urban compared to rural forests. 4. Forests within urban landscapes experienced higher levels of turnover in site occupancy, and birds settling in urban areas initiated nests later, had marginally smaller body sizes and exhibited lower return rates following nest predation than birds in more rural landscapes. In this way, behavioural processes governing habitat selection, settlement patterns and site fidelity probably contributed to the lower levels of reproductive productivity achieved by pairs nesting in urban landscapes. 5. This study provides evidence that the negative association between Acadian flycatchers and urbanization results from both population- and individual-level responses to urbanizing landscapes surrounding their riparian forest habitats.     

Effects of predation on clutch size and egg dispersion in the codling moth Laspeyresia pomonella

ABSTRACT.

• 1 The effects of predation on clutch size and egg dispersion in the codling moth Laspeyresia pomonella (L.) were experimentally studied in an orchard by recording survival of eggs glued onto different substrates.
• 2 Egg mortality due to sucking insects was readily distinguishable from that due to chewing insects.
• 3 In both the field and laboratory, females preferred to deposit eggs singly on the uppersides of leaves.
• 4 Eggs on the uppersides of leaves and on fruit survived significantly better than did those on the undersides of leaves or on twigs.
• 5 Egg losses were highest during the early part of the flight season.
• 6 The smallest (one egg) and largest (nine eggs) clutches, associated with one egg-bearing leaf per twig, both suffered the lowest rates of predation. Factors selecting against oviposition on fruits and production of large clutch sizes are presented and discussed.

     

三峡地区柏木种子萌发和幼苗更新的研究

对三峡地区柏木(Cupressus funebris)林柏木种子的萌发、幼苗存活、幼苗生长进行了研究.结果表明,(1)柏木种子的萌动期约为10 d,播种35-45 d后进入萌发高峰期,柏木种子的平均萌发率为47.7%.土壤基质对种子萌发的影响是极显著的,光照对萌发则没有显著的影响.(2)幼苗平均死亡率为52.6%.土壤类型和光照强度对幼苗的存活都有显著影响,在林下土和80%光照条件下幼苗的存活率最高.(3)柏木幼苗生长初期茎的生长动态呈"S"型,而叶片数量的增长动态近于直线型.幼苗生长初期生物量形成主要受光照条件的影响,土壤类型的影响不显著.土壤和光照条件对柏木林柏木幼苗的更新都有显著影响,但是土壤条件主要影响种子萌发和幼苗的存活,而光照条件则主要对幼苗的生长和存活产生影响.     

Are raccoons limited by the availability of breeding resources? Evidence of variability in fecundity at fine spatial scales

Despite their behavioral plasticity, recent research suggests raccoons (Procyon lotor) exhibit variability in demography and genetic structure among individual habitat patches in landscapes heavily affected by anthropogenic land use. Consequently, elucidation of vital rates at fine-spatial scales is needed to implement appropriate management strategies for this species. To evaluate the degree of variability in productivity that exists among individual habitat patches, we collected reproductive (n = 170) and cementum annuli age data (n = 383) for raccoons occupying 30 forest patches varying in local and landscape-level habitat attributes within a highly fragmented agricultural ecosystem. Across all females sampled, pregnancy rates averaged 85% but were highly variable among ages (range: 47–100%). Average litter sizes ranged from 3.2 to 4.7, but did not differ as a function of age. At the landscape-level, we observed significant variability among habitat patches in the total number of offspring produced (range: 0–80), indicating that individual patches vary in their contribution to the overall size and stability of the global (landscape-level) population. Variability in productivity among habitat patches primarily was driven by local differences in the availability of denning resources, likely because of the influence of this variable on variability in the number, age structure, and reproductive rate of females. Our results suggest that in agricultural ecosystems, the reproductive potential and temporal stability of raccoons within individual habitat fragments is inextricably linked to the density of tree cavities. © 2012 The Wildlife Society.     

Interference competition between coyotes and raccoons: a test of the mesopredator release hypothesis

Some predator species appear to conform to the mesopredatorrelease hypothesis (MRH), in which larger predators help limitpopulations of smaller predators. This hypothesis has been usedto explain the possible relationship between coyotes, mesopredators,and resultant cascades involving nonpredators. However, relationshipsbetween coyotes and noncanid mesopredators are poorly understood,and predictions from the MRH have rarely been rigorously tested.We monitored sympatric raccoon and coyote populations to assess2 predictions derived from the MRH: coyote predation is an importantcause of mortality in raccoon populations or raccoons avoidareas used by coyotes. Between March 2000 and September 2001,we recorded 3553 locations for 27 radio-collared raccoons and1393 locations for 13 coyotes captured on the Max McGraw WildlifeFoundation in Illinois, USA. No raccoon mortality from coyotepredation was observed during the study, and raccoon survivalwas >0.7 each season. All raccoon 95% home ranges exhibitedoverlap with 95% coyote home ranges in each season. The meanproportion of raccoon locations within 95% coyote home rangesdid not vary by sex but did vary by season. Raccoon overlapof coyote core areas varied considerably among individuals withinseasons, ranging from 0% to 83%. However, 45% of raccoons had<10% overlap with coyote core areas, whereas only 14% ofraccoons exhibited >50% overlap. Mean overlap with core areasdid not vary by season or sex. For those raccoons with homeranges overlapping coyote core areas, mean proportion of observedraccoon locations within coyote core areas was generally greaterthan the mean proportion of random locations. Scent-stationexperiments failed to document raccoon avoidance of specificsites that had been marked with coyote urine. We did not findsupport for a mortality prediction or avoidance prediction tosupport MRH with regard to raccoons and coyotes. These resultssuggest that relationships among mammalian predators may notbe simply dictated by body size, particularly for species outsidethe Canidae.     

Survival and Causes of Mortality of Head-Started Western Pond Turtles on Pierce National Wildlife Refuge,Washington

ABSTRACT The western pond turtle (Actinemys marmorata) is a species of conservation concern over much of its range and is listed as endangered in Washington State. From 2000 to 2004, we used radiotelemetry to document survival and mortality factors of head-started western pond turtles (n = 68) released into Pierce National Wildlife Refuge in southwestern Washington. Survival estimates for first year and older turtles ranged from 86% to 97% and overlapping confidence intervals indicated no detectible differences among age classes or among years. Subadult turtles released at ≥90-mm carapace length apparently avoided capture by most aquatic predators, indicating that terrestrial predators should be the focus of research and management where predation on larger age-classes is a concern. High annual survival combined with the documented nesting by ≥7-year-old female head-started turtles in Washington suggest that recruitment of adults is being achieved; however, head-starting is only practical as an interim solution and strategies for effective removal of aquatic predators must be developed and implemented where natural recruitment is inadequate to maintain populations.     

Population Ecology of the Eastern Box Turtle in a Fragmented Landscape

Abstract: In the mid-Atlantic region, urban sprawl and development have resulted in habitat alterations and fragmentation; however, the effects on eastern box turtle (Terrapene carolina carolina) populations are unclear. To investigate the status of eastern box turtle populations in a fragmented landscape, we used mark—recapture and radiotelemetry to estimate population density, sex ratio, age structure, and survival on 4 study areas with differing degrees of isolation and human disturbance in northern New Castle County, Delaware, USA. We estimated adult population densities ranging from 0.81 turtles/ha to 3.62 turtles/ha among our 4 study areas. Sex ratios were male-biased at 2 study areas and balanced at 2 study areas. Proportion of juveniles ranged from 0% to 31%. Estimated annual survival rate ranged from 0.813 to 0.977. Mortality of radiotagged and marked turtles was primarily due to natural causes, but mowing was the primary cause of human-induced mortality. We found evidence of population decline at one study area due to low survival and recruitment. Human disturbances, isolation, and habitat composition appear to have the greatest influence on the box turtle populations we studied. To minimize mortality from human disturbance, we suggest planting crops adjacent to forest habitat that require no mowing or mowing at a height ≥15 cm. (JOURNAL OF WILDLIFE MANAGEMENT 72(3):745–753; 2008)     

Structure and projected decline of a Karoo dwarf tortoise population

Inconspicuous, secretive, or sparsely distributed species receive relatively little research attention, potentially leading to uncertainty about their status and lack of efforts to conserve them. Karoo dwarf tortoises (Chersobius boulengeri) are endemic to South Africa, spend most of the time in retreats at remote arid locations, and are seldom seen. We conducted a 3-year (2018–2020) mark-recapture study to investigate the size and structure of the only Karoo dwarf tortoise population currently known to exist. The population in the 16-ha core of our study site consisted primarily of adult males and females, at a density of 3.3 individuals/ha. Many individuals had severely worn shells and appeared old. Small individuals (straight carapace length <65 mm) represented just 8% of the population and were mostly recent hatchlings. Overall, tortoises had high estimated survival rates (0.77–0.95; lower 95% confidence limit for the smallest tortoises was 0.16), despite a 15-month drought. The lack of small individuals may reflect low levels of recruitment and population decline. Predation by corvids was an obvious threat to all size classes. We estimated that the local population across the 250-ha study area was 800–900 males and females, and recommend precautionary conservation measures focused on reducing human-subsidized avian predation.     

Population demography of frillneck lizards (Chlamydosaurus kingii,Gray 1825) in the wet‐dry tropics of Australia

We explore the effects of biotic and abiotic factors on the population demography of frillneck lizards (Chlamydosaurus kingii) in the Australian wet‐dry tropics. Annual growth rates of males were significantly higher across all body sizes compared to females, resulting in a significant larger maximum body size in males. Both male and female lizards were highly philopatric and 81% of the among‐year recapture distances were less than 200 m. Juvenile and adult frillnecks were subjected to low but highly variable annual survival rates. Both proportion of juveniles and relative proportion of reproductive females showed extensive among‐year variations. No relationship was, however, observed between proportion of gravid females and that of juveniles captured during the subsequent year. High rainfall in January was negatively correlated with recruitment most likely caused by increased egg/embryo mortality due to flooding of nest sites. We therefore suggest that the lack of association between female reproduction and juvenile recruitment was due to the effects of stochastic variation in January rainfall. Lizard numbers increased during the first five years of the study followed by a decline during the subsequent four years. Our analyses show that annual variation in survival constituted the main determinant in driving the annual change in frillneck numbers. Surprisingly, no relationship was observed between fillneck population dynamics and annual variation in juvenile recruitment. We suggest that the 7‐years over which these analyses were conducted were insufficient to detect any significant effects of recruitment on lizard numbers, demonstrating the need for long‐term studies to accurately document vertebrate population demographic processes in areas experiencing stochastic variations rainfall such as the Australian wet‐dry tropics.     

Estimating Population Growth and Recruitment Rates Across the Range of American Common Eiders

Sound management of bird populations rests upon an adequate understanding of their population dynamics. Our study evaluated recruitment and population growth rates of 14 American common eider (Somateria mollissima dresseri) colonies from Labrador, Nova Scotia, Quebec, Canada, and Maine, USA, during various periods between 1970 and 2019. We used Pradel mark-recapture models to estimate colony-specific growth rates and the relative contributions of survival and recruitment on growth. We also validated this approach using annual nest counts (~8,000 pairs) conducted between 2003 and 2019 during down harvest operations in 3 colonies located in the Saint Lawrence estuary in Quebec. There was generally a good agreement between estimates derived using the 2 approaches. We considered that capture-recapture data were suitable to estimate population trends of common eiders in other colonies, especially for colonies where accurate nest monitoring is impaired by dense vegetation. The breeding abundance declined at major colonies in Maine and Nova Scotia and increased or was stable in Quebec and Labrador. Female survival contributed the most to population growth, but variation in recruitment among colonies was more important than variation in survival to explain population growth. Management measures should thus strive to maximize local recruitment in colonies with declining populations. The assumption that apparent survival probabilities were homogeneous throughout an individual capture history was violated at several colonies in Quebec and Labrador. Using recaptures and band recoveries, we showed that the lower apparent survival for newly marked individuals compared to females that had been recaptured at least once was caused by a difference in site fidelity rather than true survival. But <1% of recaptured females dispersed to another colony for breeding, indicating that the lower site fidelity could be related to heterogeneity in capture probability among individuals. © 2021 The Wildlife Society.