High Adult Survival Research Articles

Demographic insights for the endangered Apennine yellow-bellied toad in the Pollino National Park (Southern Italy). A five-year Capture-Mark-Recapture study

Investigating population structure, parameters, and growth over time is vital for conserving endangered taxa like the Apennine yellow-bellied toad (Bombina variegata pachypus) in Italy. The Apennine yellow-bellied toad faces habitat loss or degradation, disease, and climate change threats. Our study delves into the population dynamics of this endemic amphibian by monitoring populations in two breeding sites within the Pollino National Park (Southern Italy) using a five-year Capture-Mark-Recapture (CMR) approach. With a particular emphasis on demographic parameters such as population size, detectability, survival, temporary emigration probability, and body condition index, the research aims to contribute to understanding population dynamics and inform conservation efforts. We used two CMR models to estimate these parameters: Jolly-Seber with POPAN parametrisation and Pollock's robust design with Huggins' estimator. Results showed variation in body size between males and females, challenging previous findings in south-central Italy. For both populations, demographic data indicate high annual adult survival, fidelity to the breeding areas, support for no movement, and minimal trap response. Abundance over the years reveals a slight decline in one site and a gradual increase in the other. The estimated maximum population size indicated ∼ 92 animals in one population and ∼ 70 in the other one. Despite the high conservation concern for the Apennine yellow-bellied toad, there remains a dearth of quantitative information on demographic aspects in Southern Italy. The findings underscore the importance of protected areas in biodiversity conservation and contribute to understanding the B. v. pachypus conservation status, suggesting that small, isolated populations may be vulnerable to unpredictable fluctuations, inbreeding depression, and extinction risks. Additionally, the research emphasises the importance of long-term CMR studies to gain insights into population dynamics and develop effective conservation strategies and management practices, particularly in the face of climate changes that may impact both the endemic taxon and its habitat.

Should I stay or should I go? Coral bleaching from the symbionts' perspective.

Coral bleaching, the stress-induced breakdown of coral-algal symbiosis, threatens reefs globally. Paradoxically, despite adverse fitness effects, corals bleach annually, even outside of abnormal temperatures. This generally occurs shortly after the once-per-year mass coral spawning. Here, we propose a hypothesis linking annual coral bleaching and the transmission of symbionts to the next generation of coral hosts. We developed a dynamic model with two symbiont growth strategies, and found that high sexual recruitment and low adult coral survivorship and growth favour bleaching susceptibility, while the reverse promotes bleaching resilience. Otherwise, unexplained trends in the Indo-Pacific align with our hypothesis, where reefs and coral taxa exhibiting higher recruitment are more bleaching susceptible. The results from our model caution against interpreting potential shifts towards more bleaching-resistant symbionts as evidence of climate adaptation-we predict such a shift could also occur in declining systems experiencing low recruitment rates, a common scenario on today's reefs.

Climatic variation influences annual survival of an island‐breeding tropical shorebird

Global biodiversity loss is a major environmental concern. The wildlife on islands are particularly vulnerable to threats posed by alien predators, habitat loss and overexploitation. Effective conservation management of vulnerable species requires reliable information on vital population rates for all life stages and an understanding of key environmental drivers. However, demographic data are often not available for island populations before they decline or are extirpated. Here, we use Cormack–Jolly–Seber (CJS) models and 15 years of data for 1370 juveniles and 687 adults to estimate apparent survival for a genetically distinct resident population of Kentish plovers Charadrius alexandrinus on the island of Maio, Cabo Verde. We report two main findings. First, environmental conditions have a large effect on demographic performance since chicks that hatch during dry years experience a tenfold reduction in first‐year survival compared to chicks that hatch during wet years. Second, female and male plovers in Maio are expected to live for 7.41 ± 0.69 (mean ± SE) years and 6.75 ± 0.64 years, respectively, due to relatively high annual survival among comparable‐sized shorebirds. High adult survival thus could buffer the population against low reproductive success that this population has experienced over the last decade. Cabo Verde is typical of tropical islands with increased development that can impact native breeders and/or will accelerate habitat loss. Thus, more frequent droughts associated with climate change may exacerbate the prospects of native wildlife on many islands.

High adult survival in a northern Eurasian Curlew (Numenius arquata) population

Wetland birds such as waders are in decline across Europe. Information on demography is vital for assessing the causes of population declines, but estimates are needed from multiple populations and time periods. We used capture-recapture data from 2013–2022 including 134 individuals to estimate sex-specific apparent adult survival of Eurasian Curlews from a population breeding on agricultural fields in Finland, a stronghold region for this species in Europe. Using the Cormack–Jolly–Seber-model that considers the recapture probability of individuals, we estimated apparent survival of adults to be 0.89 (SE 0.03) for males and 0.92 (SE 0.03) for females. Our estimates of adult survival are slightly higher than those previously estimated from Fennoscandian breeding grounds in 1980s–1990s (0.82–0.88). Thus, our results suggest that adult survival of populations breeding in northern Europe has not declined during the last decades. Our study supports the view that changes in reproductive success is the main cause of decline in the Eurasian Curlew populations.

The effect of adult density on the reproductive output and hatching performance of the lesser mealworm, Alphitobius diaperinus (Panzer) (Coleoptera: Tenebrionidae)

Abstract Commercial availability of insect biomass for food and feed calls for the methodical investigation of all the complications that can deteriorate the insect farming efficiency. An appropriate stocking density is thus instrumental for the establishment of sustainable and cost effective insect farming protocols; high densities may lead to reduced insect fitness and reproduction, while low densities will result to a proportionally lower per capita yield. The present study deals with the estimation of the optimum adult density of the lesser mealworm, Alphitobius diaperinus (Panzer) (Coleoptera: Tenebrionidae), a species with great potential as food and feed source based on its high growth performance and reproductive output. However, limited data is available so far regarding the effect of adult density on its reproductive performance. Four different adult densities, ranging from 1.1 to 8.2 cm2 per adult, were evaluated in laboratory experiments in terms of reproductive output (number of eggs) and larval emergence for a period of 45 days of continuous oviposition. According to our results, the reproduction output, expressed as the cumulative number of eggs per adult and the cumulative larval hatching rate, was not affected by the adult densities tested here. Although high hatching rates that in most of the cases exceeded 85% were observed within the initial oviposition interval, these rates were in all treatments drastically reduced to 48-56% after 30 to 36 d. High adult survival (over 93%) was observed during the trial. In this experiment, the maximum reproductive output was observed in the highest density of adults that were left to oviposit continuously for a month. Data as such provide an opportunity to further exploit A. diaperinus in high-throughput production systems.

Juvenile proportion as a predictor of freshwater turtle population change

AbstractThe extreme longevity of turtles and tortoises can make it difficult to determine the conservation status of their populations because high annual adult survival may mask gradual attrition due to low levels of recruitment. When long‐term demographic trends are unknown and available data are insufficient for population modelling, it may be assumed that a scarcity of juveniles indicates low recruitment that will result in population ageing and numerical decline. However, the reliability with which the proportion of juveniles foreshadows demographic change is uncertain. We tested the hypothesis that a low proportion of juveniles in a turtle population presages its ageing by analysing over 20 years of survey data for five discrete populations of the Australian western saw‐shelled turtle (Myuchelys bellii: Chelidae), a listed threatened species. The analysis tested whether the initial proportion of juvenile turtles in each population was related to its temporal trend in average body size. The five populations had varied structure and trends, with the initial proportion of juvenile turtles ranging from 10% to 39% and average body size increasing over time in some populations and decreasing in others. Contrary to expectation, the initial proportion of juveniles was unrelated to the trend in average body size and, by inference, average age, indicating that effective trend forecasting requires more detailed demographic information than merely population structure.

Life history changes in the eastern collared lizard in response to varying demographic phases and management policies

AbstractBy 1980 eastern collared lizards (Crotaphutus collaris collaris) had experienced massive local extinction on glades (open, rocky areas imbedded in a woodland matrix) in the Ozarks, a highland region in central North America. Lizards were translocated to the Peck Ranch Conservation Area in Missouri on three restored glades starting in 1984, and went through three demographic phases: (1) an isolate phase with initial growth followed by decline in population size and no colonization of nearby glades; (2) a colonizing phase of high dispersal and population growth that started with the onset of prescribed woodland burning, and (3) a stable metapopulation phase. We used mark/recapture information on over 1500 lizards with high sample coverage to estimate life history parameters. Life history was homogeneous within each phase, but differed significantly between phases. Changes occurred in less than a generation, indicating plasticity in life history. The isolate phase was characterized by low juvenile survivorship, high adult survivorship, long generation times, an old age structure, and almost no dispersal. The colonization phase had increased yearling survival, decreased adult survival, shorter generation times, a younger age structure, and much dispersal. The stable metapopulation phase was intermediate between these two extremes. These transitions indicated trade‐offs among different life history parameters. These plastic life history attributes show that species cannot be regarded as static units, resulting in not a life history, but rather a set of feasible life histories. Ignoring this set of feasible life histories can result in poor conservation decisions.

Population dynamics and life history of the endangered ciénega endemic Eryngium sparganophyllum in Arizona

Eryngium sparganophyllum is a perennial endemic to ciénegas in warm North American deserts. Only four populations remain, yet little scientific knowledge exists to guide its conservation. Based on a spatially balanced sampling design, we quantified plant density, individual size, and reproductive potential of two populations in the U.S. We also assessed conditions influencing germination in the lab. The population in a warmer climate had a larger population size, higher short-term population growth rate, hosted larger individuals, and showed a negative correlation between plant size and plant density. In both populations, plant density was positively correlated with shallow soil moisture and probability of flowering was positively correlated with plant size. Seeds only germinated in the spring, and responded to interactions between temperature, light exposure and population location. We hypothesize that 1) recruitment of E. sparganophyllum may be episodic, relying on a rare niche opportunity of reliable shallow soil moisture and low competition; and 2) adult survival of the species may be limited by interspecific density dependence and climatic extremes. The conservation of this species depends on ensuring high adult survival and promoting recruitment, which can be accomplished through actively protecting extant populations and exploring restoration and introduction possibilities.

Post-weaning survival in kangaroos is high and constant until senescence: Implications for population dynamics.

Large herbivores typically have consistently high prime-aged adult survival and lower, more variable, juvenile, and senescent survival. Many kangaroo populations undergo greater fluctuations in density compared with other large herbivores, but age- and sex-specific survival of kangaroos and their response to environmental variation remain poorly estimated. We used long-term capture-mark-recapture data on 920 individuals to investigate the survival component of eastern grey kangaroo (Macropus giganteus) population dynamics. Forage availability and population density were monitored quarterly and included as predictors of survival in Bayesian Cormack-Jolly-Seber models. Annual survival probabilities were estimated for five age classes: 0 years (juveniles), 1-2 years (subadults), 3-6 years (prime-aged adults), 7-9 years (presenescent adults), and ≥10 years (senescent adults). Survival of juveniles varied widely during our 12-year study, ranging from 0.07 to 0.90 for females and 0.05-0.92 for males. Subadult survival was 0.80-0.93 for females and 0.75-0.85 for males, while that of prime-aged adults was ≥0.94 for females and ≥0.83 for males, despite large fluctuations in forage and density. The survival of presenescent adults spanned 0.86-0.93 for females and 0.60-0.86 for males. Senescent survival was variable, at 0.49-0.90 for females and 0.49-0.80 for males. Male survival was significantly lower than female survival in prime-aged and presenescent adults, but not in other age classes. Although most of the models supported by Watanabe-Akaike Information Criterion selection included at least one environmental covariate, none of these covariates individually had a discernible effect on survival. Temporal variability in overall survival appeared mostly due to changes in the survival of juvenile and senescent kangaroos. Kangaroo survival patterns are similar to those of ungulates, suggesting a strong role of sex-age structure on population dynamics.

Survival vs. reproduction: dimorphic life history strategy in Heermann’s gulls during warm ocean temperature anomalies

Seabirds have thrived over time in marine environments with highly variable productivity. Life history strategies favored by natural selection consist of late sexual maturation, few offspring per breeding event, high adult survival, long lifespan, and deferred breeding when food availability is low. Heermann’s gull Larus heermanni, with 95% of its world population breeding on Isla Rasa, Gulf of California, follows this common pattern, including poor breeding performance during periods of low food availability often associated with high sea surface temperatures. Our interest was to characterize individual variations in this general pattern and assess its consequences for lifetime number of fledglings produced. We compared life history parameters from a set of known-age females banded during 1984-1993 and recaptured during 1989-2013 and found that most (85%) followed the general pattern (hereafter ‘conservative’) of laying ≤2 eggs and fledging no chicks during anomalously warm years. However, 15% of the females (hereafter ‘bold’) laid eggs during all anomalously warm years and fledged chicks in most of those years. Throughout their lifespan, conservative females lived significantly longer and produced significantly more eggs, but the total number of fledglings was not significantly different between strategies. Both strategies coexist over time, persisting within the population under conditions that were common until the late 20th century. If conditions continue to vary, with the occurrence of heatwaves and increases in the frequency of anomalously warm years, bold females may have a selective advantage over conservative females, which might help mitigate the impacts of ocean warming on future populations.

Populations of a tropical epiphytic orchid are destabilized in its peripheral range by hurricane and an exotic herbivore

AbstractIn a time of global change, having an understanding of the nature of biotic and abiotic factors that drive a species' range may be the sharpest tool in the toolbox of conservation and management of threatened species. However, such information are lacking for most tropical and epiphytic species due to the complexity of life history, the roles of stochastic events, and the diversity of habitat across the span of a distribution. In this study, we conducted repeated census across the core and peripheral range of Trichocentrum undulatum, a threatened orchid that is found throughout the island of Cuba (species core range) and southern Florida (the northern peripheral range). We used demographic matrix modeling and stochastic simulations to investigate the impacts of herbivory, hurricanes, and logging (in Cuba) on projected population growth rates (λ and λs) among sites. Our study indicates that the Florida population is under high extinction risk and most populations in the core range show less interannual variability, but, with the exception of one population, are also in decline. The peripheral population experienced higher herbivory damage than did the core populations, by a native inflorescence‐crippling fly, Melanagromyza miamensis, and an invasive, mortality‐triggered scale, Diaspis boisduvalii. The latter was found in the Florida population only. Hurricanes increased levels of mortality and had a negative effect on λ. However, λ increased following hurricane events due to increased recruitment and decreased herbivory. Life table response experiments suggest that higher adult survival was the largest contributor to the higher λ observed in the growing Cuba populations, as compared with the population in Florida. Logging simulations in Cuba indicate that populations can maintain stability only if selective logging of host trees occurs at low frequency. Reintroduction of the species in its northern peripheral habitat is needed to ameliorate the threats from sea‐level rise and invasive herbivorous insects to secure the current species' northern, continental range margin. Our study exhibits how vital rates and ecological interactions vary across a species distribution and respond under differing stochastic events.

Long‐lasting effects of harsh early‐life conditions on adult survival of a long‐lived vertebrate

Early life conditions, especially in long‐lived organisms, can have both immediate and long‐lasting effects in vital traits generating demographic structure across cohorts. Multiple non‐exclusive hypotheses have been proposed to explore this question. For instance, the silver spoon, the viability selection or the predictive adaptive response hypothesis, predict that long lasting effects resulting from harsh early conditions could be negative, positive or vary with current environmental conditions, respectively. We use an 18‐year capture–mark–recapture dataset on adult Audouin's gulls Ichthyaetus audouinii to test for these different hypotheses while accounting for age, breeding experience and large‐scale dispersal. Audouin's gull cohorts experiencing harsh conditions during early life (i.e. nestling period and first winter) are known to experience lower first year survival. Here, we show that early life conditions also explained a large proportion (54%) of adult survival variation among cohorts. However, adulthood cohorts experiencing poor early life conditions had higher adult survival, in accordance with the viability selection hypothesis. Our results also show that apparent inexperienced breeders showed lower survival than experienced ones. Moreover, adult survival decreased with age. These results could suggest an increased cost of reproduction for deferred breeders, individual quality differences or survival senescence in this population. Overall, our study highlights the importance of early development, age and breeding experience as potential factors generating heterogeneity of survival between cohorts. Understanding the mechanisms driving responses to early life conditions at different life stages is fundamental to understanding the long‐term dynamics of wild populations.

Age and sex ratios in the declining West Siberian/North European population of Long-tailed Duck wintering in the Baltic Sea

The West Siberian/North European population of Long-tailed Duck (Clangula hyemalis), which breeds in the Russian Arctic and northern Fennoscandia and winters in the Baltic Sea, has declined rapidly since the 1990s. To identify the causes of the decline and initiate effective conservation measures information on basic demographic parameters is needed. A photo survey method was used to estimate female age ratios and the proportion of males among adults in wintering Long-tailed Ducks at coastal and off-shore areas in the Baltic Sea. Female age ratios were defined as the number of first winter males, assumed equal to the number of first winter females, per adult female. Several thousand individuals were sampled each winter from 2008 to 2021. Female age ratios fluctuated between years and were consistently lower in the southern than in the central Baltic Sea. The proportion of males among wintering adults birds was male-biased, more so in the southern Baltic Sea than in other regions. A population model was used to analyse if low female age ratios between 2008 and 2021 has constrained population growth. Given that the estimated weighted mean female age ratio of 0.153 was representative at the population scale, an extremely high adult female mean annual survival rate of 0.872 would have been needed to maintain a stable population. Considering known sources of anthropogenic mortality in the Baltic Sea, and instead assuming a more realistic survival rate of ca. 0.80, a population decline of ca. 7.7% per year should have occurred during the study period.

Spatial patterns in age‐ and colony‐specific survival in a long‐lived seabird across 14 contrasting colonies

Demographic rates such as recruitment and survival probability can vary considerably among populations of the same species due to variation in underlying environmental processes. If environmental processes are spatially correlated, nearby populations are expected to have more similar demographic rates than those further apart. Breeding populations and foraging ranges are spatially segregated in colonial seabirds, making them ideal for studying spatial patterns in demographic rates and their effects on local population dynamics. Here we explored variation in age‐dependent survival probabilities across 14 colonies of Herring GullsLarus argentatusbreeding along the Dutch North Sea coast. We used long‐term mark–recapture data of marked fledglings to estimate survival, and estimated spatial autocorrelation of survival probabilities. We assessed whether survival until recruitment age or until 10 years old (close to their expected lifespan) explained variation in population trajectories of each colony. Juvenile and adult survival showed a strong, but different, north‐to‐south gradient in survival probability, with lower juvenile but higher adult survival in northern colonies than southern colonies, whereas the spatial pattern of immature survival was less distinct. Neither recruitment nor the proportion of 10‐year‐old adults alive predicted whether a colony collapsed, declined, remained stable or increased. The distinct spatial pattern in survival suggests variation in regional food availability, which do not seem to drive local population dynamics. The absence of a link between survival and colony trajectories implies that connectivity between populations plays an important role affecting population dynamics.

High early death rates, treatment resistance, and short survival of Black adolescents and young adults with AML

AbstractSurvival of patients with acute myeloid leukemia (AML) is inversely associated with age, but the impact of race on outcomes of adolescent and young adult (AYA; range, 18-39 years) patients is unknown. We compared survival of 89 non-Hispanic Black and 566 non-Hispanic White AYA patients with AML treated on frontline Cancer and Leukemia Group B/Alliance for Clinical Trials in Oncology protocols. Samples of 327 patients (50 Black and 277 White) were analyzed via targeted sequencing. Integrated genomic profiling was performed on select longitudinal samples. Black patients had worse outcomes, especially those aged 18 to 29 years, who had a higher early death rate (16% vs 3%; P=.002), lower complete remission rate (66% vs 83%; P=.01), and decreased overall survival (OS; 5-year rates: 22% vs 51%; P<.001) compared with White patients. Survival disparities persisted across cytogenetic groups: Black patients aged 18 to 29 years with non–core-binding factor (CBF)-AML had worse OS than White patients (5-year rates: 12% vs 44%; P<.001), including patients with cytogenetically normal AML (13% vs 50%; P<.003). Genetic features differed, including lower frequencies of normal karyotypes and NPM1 and biallelic CEBPA mutations, and higher frequencies of CBF rearrangements and ASXL1, BCOR, and KRAS mutations in Black patients. Integrated genomic analysis identified both known and novel somatic variants, and relative clonal stability at relapse. Reduced response rates to induction chemotherapy and leukemic clone persistence suggest a need for different treatment intensities and/or modalities in Black AYA patients with AML. Higher early death rates suggest a delay in diagnosis and treatment, calling for systematic changes to patient care.

Hunting and environmental influences on survival of male wild turkeys in Virginia and West Virginia

AbstractKnowledge of the effects of hunting and environmental influences on survival of eastern wild turkeys (Meleagris gallopavo silvestris) is critical to managers setting fall and spring hunting seasons. Research has shown improper season frameworks can result in unsustainably high harvest rates of adult males, affect male age structure, and result in lower hunter satisfaction. Our objectives were to estimate survival rates of males, identify causes of mortality, and relate hunting and environmental influences to male turkey survival. We captured and radio‐tagged male wild turkeys in Virginia (n = 204) and West Virginia (n = 197), USA, during 2004–2007. We used staggered entry Kaplan‐Meier models to estimate survival and Cox Proportional Hazards Models to estimate effects of predictor variables on survival. Survival was estimated for 3 distinct periods of interest: annual, fall hunting (October–January), and spring hunting (April–May). The leading causes of mortalities (209 turkeys) were legal spring harvest (42%), predation (25%), and poaching (17%). Only 8 turkeys (4%) were taken during fall hunting seasons. Confidence intervals for annual survival of 2 year‐old and 3+ year‐old turkeys overlapped; therefore, we combined adult ages into a single category (2+). Adult (2+) annual survival was 0.63 (95% CI = 0.58–0.69) and the harvest rate was 25% (95% CI = 20–29%) for the combined states. Annual survival rates for adults (2+) were greater than in most other published studies, whereas adult (2+) spring harvest rates were lower. For juvenile males, annual survival was 0.74 (95% CI = 0.68–0.79) and spring harvest rate was 7% (95% CI = 3–11%). High juvenile and adult (2+) survival may have been related to low harvest rates. Adult turkeys (2+) had 46% greater risk of dying than one‐year‐old birds and were 3.7 times more likely to be harvested than juveniles. Age, a relative phenology index (RPI; spring green‐up), and white oak (Quercus alba) acorn production were included in the top models for annual survival, spring season survival, and spring harvest risk. Increasing RPI (more foliage) decreased mortality risk and greater white oak (Quercus alba) acorn abundance increased mortality risk. Across 4 regions in the 2 states, fall survival was high (0.90, 95% CI = 0.87–0.93). The impact of fall hunting on males in Virginia was low (5% harvest rate, 95% CI = 0–9%). Overall, spring harvest had the greatest effect on male survival, although those effects were moderated by the previous fall white oak crop and the onset of green‐up in the spring.

Life-history traits facilitate the population success of the sergeant major Abudefduf saxatilis (Linnaeus, 1758, Perciformes: Pomacentridae) in the Caribbean Sea

ABSTRACT Trade-offs among life-history traits (e.g. growth, reproduction, and survival) are fundamental to the population success of living beings in the wild. This study describes the life-history traits of the sergeant major, Abudefduf saxatilis, one of those fishes most abundant in the coral reefs of the Caribbean Sea. The reproductive biology, age, growth, and abundance of a particular population of A. saxatilis from Mexico was explored using 12 monthly samplings to collect 414 specimens, and abundance monitoring through visual censuses for age-based demographic analysis. Our results indicated that A. saxatilis would have an opportunistic strategy with a type II survivorship curve since the studied population was characterized by fast growth, maturation at intermediate sizes (≈11 cm L T or 2.5 yrs. old), with batch spawning and indeterminate fecundity, protracted spawning season (January to September), high abundance of recruits, low instantaneous natural mortality (M = 0.114 year −1), high life expectancy at birth (e 0 ≈ 4.7 yrs.) and maturity (e α ≈ 2.8 yrs.), and high annual survival of adults and high survival to maturity (). All these life-history traits facilitate the population success of A. saxatilis, showing a high reproductive effort and a rapid population turnover, making this species an efficient colonizer.

Crowding does not affect monarch butterflies' resistance to a protozoan parasite.

Host density is an important factor when it comes to parasite transmission and host resistance. Increased host density can increase contact rate between individuals and thus parasite transmission. Host density can also cause physiological changes in the host, which can affect host resistance. Yet, the direction in which host density affects host resistance remains unresolved. It is also unclear whether food limitation plays a role in this effect. We investigated the effect of larval density in monarch butterflies, Danaus plexippus, on the resistance to their natural protozoan parasite Ophryocystis elektroscirrha under both unlimited and limited food conditions. We exposed monarchs to various density treatments as larvae to mimic high densities observed in sedentary populations. Data on infection and parasite spore load were collected as well as development time, survival, wing size, and melanization. Disease susceptibility under either food condition or across density treatments was similar. However, we found high larval density impacted development time, adult survival, and wing morphology when food was limited. This study aids our understanding of the dynamics of environmental parasite transmission in monarch populations, which can help explain the increased prevalence of parasites in sedentary monarch populations compared to migratory populations.

Tiny Tree‐Dwelling Turtles

Photo 1. Female spotted turtle ABK, who nested successfully in June after spending the 2019–20 winter inside the swamp white oak tree (Quercus bicolor) with multiple males. ABK also spent the following winter inside the oak tree hibernaculum. Photo credit: Roy Nagle. Photo 2. Male spotted turtle NVX in a shallow, soft-bottomed rivulet formed by flooding from a beaver dam. Beavers expand spotted turtle foraging habitats and provide aquatic corridors for movements among seasonal habitats and to prospective habitats. During 2021, this male rendezvoused inside the swamp white oak tree with other spotted turtles intermittently from March 14 to April 12 and then moved away to forage among shallow wetlands fortified by beavers. Photo credit: Roy Nagle. Photo 3. Young (a) and older (b) male spotted turtles: (a) AKV is ~8 years old, with relatively distinct growth annuli and new growth indicated by light-colored line down the middle of plastron; (b) BKV is considerably older and has a visible injury to his left pectoral scute. Like most older, sexually mature males in the population, BKV spent much of March and early April 2021 inside the oak tree with several females. In contrast, juvenile AKV spent only four days inside the tree, in mid-April after the major mating period, apparently for shelter between foraging bouts rather than rendezvousing with potential mates. Photo credits: Roy Nagle. Photo 4. (a) Adult male spotted turtle AJW on the move following an autumn rain. This male spent two weeks inside the hollow oak tree during the latter half of March 2021, along with four females and six other males. AJW apparently has a particular affinity for female ABH, as he was captured alongside her on four different occasions entering or exiting the tree. (b) Female spotted turtle NYY, one of only four reproductive adult females in our study population. Most spotted turtle populations are small and fragmented, a primary reason the species is currently under review by the U.S. Fish and Wildlife Service for federal listing under the Endangered Species Act. Photo credits: Travis Russell. Photo 5. One-year-old spotted turtle captured in a flooded meadow in June. Substantial new growth is indicated by light coloration between scutes. Like many long-lived turtles, spotted turtle populations are characterized by low fecundity and low recruitment of juveniles, which contrasts with high adult survivorship required for stable populations. Photo credit: Roy Nagle. These photographs illustrate turtles from the article, “Sheltering oak: spotted turtles in a tree” by Roy D. Nagle, Travis J. Russell, and Ryan J. Rimple published in Ecology. http://doi.org/10.1002/ecy.3585.

Variation in Demography and Life-History Strategies Across the Range of a Declining Mountain Bird Species

Species- and population-specific responses to their environment may depend to a large extent on the spatial variation in life-history traits and in demographic processes of local population dynamics. Yet, those parameters and their variability remain largely unknown for many cold-adapted species, which are exposed to particularly rapid rates of environmental change. Here, we compared the demographic traits and dynamics for an emblematic bird species of European mountain ecosystems, the ring ouzel (Turdus torquatus). Using integrated population models fitted in a Bayesian framework, we estimated the survival probability, productivity and immigration of two populations from the Western European Alps, in France (over 11 years) and Switzerland (over 6 years). Juvenile apparent survival was lower and immigration rate higher in the Swiss compared to the French population, with the temporal variation in population growth rate driven by different demographic processes. Yet, when compared to populations in the northwestern part of the range, in Scotland, these two Alpine populations both showed a much lower productivity and higher adult survival, indicating a slower life-history strategy. Our results suggest that demographic characteristics can substantially vary across the discontinuous range of this passerine species, essentially due to contrasted, possibly locally evolved life-history strategies. This study therefore raises the question of whether flexibility in life-history traits is widespread among boreo-alpine species and if it might provide adaptive potential for coping with current environmental change.