Assessing senescence patterns in populations of large mammals

Theoretical models such as those of Gompertz and Weibull are commonly used to study senescence in survival for humans and laboratory or captive animals. For wild populations of vertebrates, senescence in survival has more commonly been assessed by fitting simple linear or quadratic relationships between survival and age. By using appropriate constraints on survival parameters in Capture-Mark-Recapture (CMR) models, we propose a first analysis of the suitability of the Gompertz and the two-parameter Weibull models for describing aging-related mortality in free-ranging populations of ungulates. We first show how to handle the Gompertz and the two-parameter Weibull models in the context of CMR analyses. Then we perform a comparative analysis of senescence patterns in both sexes of two ungulate species highly contrasted according to the intensity of sexual selection. Our analyses provide support to the Gompertz model for describing senescence patterns in ungulates. Evolutionary implications of our results are discusse

Evaluación de pautas de senescencia en poblaciones de grandes mamíferos

Theoretical models such as those of Gompertz and Weibull are commonly used to study senescence in survival for humans and laboratory or captive animals. For wild populations of vertebrates, senescence in survival has more commonly been assessed by fitting simple linear or quadratic relationships between survival and age. By using appropriate constraints on survival parameters in Capture–Mark–Recapture (CMR) models, we propose a first analysis of the suitability of the Gompertz and the two-parameter Weibull models for describing aging–related mortality in free–ranging populations of ungulates. We first show how to handle the Gompertz and the two–parameter Weibull models in the context of CMR analyses. Then we perform a comparative analysis of senescence patterns in both sexes of two ungulate species highly contrasted according to the intensity of sexual selection. Our analyses provide support to the Gompertz model for describing senescence patterns in ungulates. Evolutionary implications of our results are discussed.Por lo general, para estudiar el papel que desempeña la senescencia en la supervivencia, ya sea en humanos, en animales de laboratorio o en animales cautivos. Se emplean modelos teóricos, como los de Gompertz y Weibull. En el caso de las poblaciones silvestres de vertebrados, dicho papel tiende a evaluarse ajustando relaciones lineales o cuadráticas simples entre la supervivencia y la edad. En el presente estudio proponemos —a partir de la aplicación de constricciones apropiadas en los parámetros de supervivencia empleados en los modelos de captura–marcaje–recaptura (CMR)— un primer análisis de la idoneidad del modelo de Gompertz y del modelo de dos parámetros de Weibull para describir la mortalidad relacionada con el envejecimiento en poblaciones de ungulados criadas en régimen de pasto libre. En primer lugar indicamos cómo emplear el modelo de Gompertz y el modelo de dos parámetros de Weibull en el contexto de los análisis de CMR, para seguidamente llevar a cabo un análisis comparativo de las pautas de senescencia en dos especies de ungulados de sexos opuestos, altamente contrastadas según la intensidad de la selección sexual. Nuestro análisis apoya el modelo de Gompertz para la descripción de pautas de senescencia en ungulados. Se discuten las implicaciones evolutivas de los resultados obtenidos

Operational Improvement of a Chiller to Reduce Water Usage in the Cooling of Turkey Cuts

Cleaner production is the application of an environmental strategy that seeks to integrate the production processes with products and services so as to reduce the risks to humans and the environment. This work gathers data from a study conducted in a slaughterhouse for birds in the production of Turkey leg quarters. An improvement opportunity was identified in the water consumption of the sanguine fluid removal process of the Turkey leg quarters with a particular technological chiller. The area of intervention was chosen because of its history of higher-than-expected water consumption in relation to the acceptable limit negotiated with the local Federal Inspection Service. The evaluated criteria were water flow per kilo of leg quarter and the structure of the adsorption equipment used in the industry. The results of these analyses were directly linked to water savings and changes in equipment, increasing knowledge about the implementation of cleaner production in the slaughterhouse industry, aligned to the continuous improvement of the process. The control of the water flow and the direct changes made in the chiller resulted in water savings of 83,435 L/week and 1,001,220 liters/year, based on the production of the slaughterhouse under study, in addition to savings of R$289.52 per week or R$72,959.04 per year

Maternal longevity and offspring sex in wild ungulates

In species with sexual size dimorphism, the offspring of the larger sex usually have greater energy requirements and may lead to greater fitness costs for parents. The effects of offspring sex on maternal longevity, however, have only been tested in humans. Human studies produced mixed results and considerable debate mainly owing to the difficulty of distinguishing the effects of sexual dimorphism from sociocultural factors. To advance this debate, we examined how the relative number of sons influenced maternal longevity in four species of free-living ungulates (Soay sheep Ovis aries ; bighorn sheep, Ovis canadensis ; red deer, Cervus elaphus ; mountain goat, Oreamnos americanus ), with high male-biased sexual size dimorphism but without complicating sociocultural variables. We found no evidence for a higher cumulative cost of sons than of daughters on maternal longevity. For a given number of offspring, most females with many sons in all four populations lived longer than females with few sons. The higher cost of sons over daughters on maternal lifespan reported by some human studies may be the exception rather than the rule in long-lived iteroparous species

Caribou herd dynamics : impacts of climate change on traditional and sport harvesting

Caribou (Rangifer tarandus) are a key species in Arctic ecosystems including northern Québec and Labrador. They play a central role in the ecology of predators and the structure of Arctic plant communities. In addition, caribou provide socioeconomic and cultural benefits from subsistence and sport hunting activities. Changes in the distribution and abundance of caribou due to global climate change would have serious biological, societal, and economic implications. Direct and indirect consequences of climate change on migratory caribou herds may include alteration in habitat use, migration patterns, foraging behaviour and demography. For example, caribou may experience a further northerly shift in distribution due to several factors including longer ice-free periods, increases in snowfall and extreme weather events, alterations in the fire regime, and changes in the distribution of insects and predators. Future research by Caribou Ungava, a research group interested in the ecology of migratory caribou in the context of climate change, will address the factors outlining variations in the population dynamics of caribou, implications for survival and reproduction, as well as the response of caribou habitat to different climate change scenarios. Management efforts focusing on mitigating greenhouse gases to reduce the potential effects of climate change, preserving high quality habitat, limiting anthropogenic landscape disturbances, and managing hunting in a sustainable manner, could alleviate stressors on migratory caribou of the QuébecLabrador peninsula

Can ground counts reliably monitor ibex Capra ibex populations

: Can ground counts reliably monitor ibex Capra ibex populations? -Wildl. Biol. 14: 489-499. Although ground counts are often used to monitor ungulate populations, several studies show that counts of ungulates have low precision and often underestimate population size. We assessed the reliability of ibex Capra ibex counts as performed in French national parks, by analysing up to 23 years of annual censuses of six ibex populations for which a subset of animals were individually marked. We compared the population growth rate obtained from census data (estimated by use of four different methods) with the growth rate calculated from a demographic model including parameters estimated from capture-markrecapture methods. The correlations between count-based estimates and growth rate obtained from demographic models were adequate to suggest that ground counts can monitor trends in population size of ibex, provided that the occasional undercounts are identified. Substantial undercounts in some years led to biologically impossible values of yearly population growth (l>1.35) and, in the longest time series available, to marked autocorrelations in counts. Managers should replicate counts within the same year to check for underestimated counts. To reduce errors, population biologists analysing time series of ungulate counts should check the plausibility of annual growth rates estimated from two consecutive counts

Protecting biodiversity in British Columbia: Recommendations for developing species at risk legislation

British Columbia has the greatest biological diversity of any province or territory in Canada. Yet increasing numbers of species in British Columbia are threatened with extinction. The current patchwork of provincial laws and regulations has not effectively prevented species declines. Recently, the Provincial Government has committed to enacting an endangered species law. Drawing upon our scientific and legal expertise, we offer recommendations for key features of endangered species legislation that build upon strengths and avoid weaknesses observed elsewhere. We recommend striking an independent Oversight Committee to provide recommendations about listing species, organize Recovery Teams, and monitor the efficacy of actions taken. Recovery Teams would evaluate and prioritize potential actions for individual species or groups of species that face common threats or live in a common area, based on best available evidence (including natural and social science and Indigenous Knowledge). Our recommendations focus on implementing an adaptive approach, with ongoing and transparent monitoring and reporting, to reduce delays between determining when a species is at risk and taking effective actions to save it. We urge lawmakers to include this strong evidentiary basis for species recovery as they tackle the scientific and socioeconomic challenges of building an effective species at risk Act

Protecting biodiversity in British Columbia: Recommendations for developing species at risk legislation

British Columbia has the greatest biological diversity of any province or territory in Canada. Yet increasing numbers of species in British Columbia are threatened with extinction. The current patchwork of provincial laws and regulations has not effectively prevented species declines. Recently, the Provincial Government has committed to enacting an endangered species law. Drawing upon our scientific and legal expertise, we offer recommendations for key features of endangered species legislation that build upon strengths and avoid weaknesses observed elsewhere. We recommend striking an independent Oversight Committee to provide recommendations about listing species, organize Recovery Teams, and monitor the efficacy of actions taken. Recovery Teams would evaluate and prioritize potential actions for individual species or groups of species that face common threats or live in a common area, based on best available evidence (including natural and social science and Indigenous Knowledge). Our recommendations focus on implementing an adaptive approach, with ongoing and transparent monitoring and reporting, to reduce delays between determining when a species is at risk and taking effective actions to save it. We urge lawmakers to include this strong evidentiary basis for species recovery as they tackle the scientific and socioeconomic challenges of building an effective species at risk Act

Patterns of body mass senescence and selective disappearance differ among three species of free-living ungulates

Declines in survival and reproduction with age are prevalent in wild vertebrates, but we know little about longitudinal changes in behavioral, morphological, or physiological variables that may explain these demographic declines. We compared age-related variation in body mass of adult females in three free-living ungulate populations that have been the focus of long-term, individual-based research: bighorn sheep (Ovis canadensis) at Ram Mountain, Canada; roe deer (Capreolus capreolus) at Trois Fontaines, France; and Soay sheep (Ovis aries) on St. Kilda, Scotland. We use two recently proposed approaches to separate contributions to age-dependent variation at the population level from within-individual changes and between-individual selective disappearance. Selective disappearance of light individuals in all three populations was most evident at the youngest and oldest ages. In later adulthood, bighorn sheep and roe deer showed a continuous decline in body mass that accelerated with age while Soay sheep showed a precipitous decrease in mass in the two years preceding death. Our results highlight the importance of mass loss in explaining within-individual demographic declines in later adulthood in natural populations. They also reveal that the pattern of senescence, and potentially also the processes underlying demographic declines in late life, can differ markedly across related species with similar life histories