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This paper presents unique data on the reproductive behavior of the rare giant armadillo (Priodontes maximus), including gestation, inter-birth intervals, number of offspring and parental care. It also describes a potential non-parental infanticide. The study used telemetry, camera traps and track observations for over 7 years in a 300-km2 area in the central Brazilian Pantanal. Females with young were recorded 5 times. Reproductive events did not appear to be seasonal. A 5-month gestation period was estimated. Parental care is long, as the offspring is completely dependent on its mother's milk until 6–8 months of age. Weaning was estimated to occur at 11–12 months, but the offspring continued to be dependent on its mother's burrows until 18 months old. Three births were recorded over a 6-year period for one individual. The offspring from the first birth recorded was killed at 4 weeks of age in a potential infanticide, but 7 months after the first birth, a second offspring was born. A third birth was recorded 3 years after the second birth. Results from this study suggest that the population growth rate of giant armadillos is very low and the species can therefore easily be locally extirpated. [ABSTRACT FROM AUTHOR]

Morphometrics is the quantitative study of organisms shape and size. Intrinsic (e.g. age and sex) and extrinsic (e.g. abiotic conditions) factors can be related to morphological diversity and can aid in the study of species biology and ecology. Giant armadillos have rarely been captured in the wild and very little is known about the species. Here we aimed to characterize body measurements of free-living giant armadillos (Priodontes maximus) in mid-western Brazil and evaluate how these measurements vary between sexes and age classes to gain insights on the species biology and ecology. We captured 28 armadillos in the study area, 18 adults (9 males, 9 females) and 10 subadults (6 males, 4 females) and assessed twenty-five different morphometric measurements for each captured armadillo. To evaluate if age class and sex of adult individuals can be differentiated by a concise set of morphometric measurements we used Linear Discriminant Analyses. We encountered significant morphometric differentiation between age classes and report seven parameters that best discriminate individuals between age classes which may allow the identification of individual's age class in future studies. The wide morphometric variation in subadults could indicate that individuals have a long developmental process between weaning and sexual maturity. Morphometric differentiation between sexes was possible through the association of three morphological parameters and adult males are larger and heavier than females. Although we were limited by the number of animals sampled in previous studies, females presented similar body mass across studied sites, while males presented variation of up to ten kilos across the species distribution. This indicates that the degree of sexual dimorphism can vary among localities and raises interesting ecological questions regarding the species reproductive system. This variation can be related to abiotic factors (e.g. latitude, temperature and topography), differences in productivity among biomes (i.e. resource abundance and distribution), population density, and/or genetic variation between populations and should be explored further. We propose the measurements used here be used as standard measurements for this species since it encompasses all of the most distinctive features of the species and allows a full morphological characterization, enabling the future comparison between populations of this widely distributed species. [ABSTRACT FROM AUTHOR]

The natural history of the southern naked-tailed armadillo Cabassous unicinctus squamicaudis is not well known. Here, we provide basic information about burrow systems, home ranges, activity, morphometric measures, and reproductive behaviour. We monitored 10 individuals through VHF telemetry and direct observations in the central Pantanal of Brazil for 24 months. Males (2.06 km 2 ) had significantly larger home ranges than females (0.59 km 2 ) and home ranges of males overlapped with those of several females. There was very little overlap in ranges of the same sex and very few social interactions were observed. Southern naked-tailed armadillos dug convoluted galleries to forage, and, unless they used their entrance to exit, they emerged on average 2 m away (ranging from 0.01 m to 17 m) from the burrow entrance. When leaving their burrows, they spend on average 6.5 min above ground, travelling an average of 83 m (ranging from 1 m to 781 m) before going back underground. They do not return to sleep in a particular burrow, changing burrows frequently. The studied armadillos were diurnal, and spend 99.25% of the day underground, emerging only during the hottest period of the day (mid-afternoon). The southern naked-tailed armadillos should be classified as a subterranean species, rather than fossorial since they spent most of their time underground where foraging also takes place. Minimum densities of C. u. squamicaudis were estimated at 2.21 adults/km 2 . Gestation was estimated to last for 4 months. Parental care of a single young lasted on average 4 months. Niche overlap between E. sexcinctus and C. u. squamicaudis in the study area is minimal. [ABSTRACT FROM AUTHOR]

The natural history of the southern naked-tailed armadillo Cabassous unicinctus squamicaudis is not well known. Here, we provide basic information about burrow systems, home ranges, activity, morphometric measures, and reproductive behaviour. We monitored 10 individuals through VHF telemetry and direct observations in the central Pantanal of Brazil for 24 months. Males (2.06km2) had significantly larger home ranges than females (0.59 km2) and home ranges of males overlapped with those of several females. There was very little overlap in ranges of the same sex and very few social interactions were observed. Southern naked-tailed armadillos dug convoluted galleries to forage, and, unless they used their entrance to exit, they emerged on average 2m away (ranging from 0.01 m to 17m) from the burrow entrance. When leaving their burrows, they spend on average 6.5 min above ground, travelling an average of 83 m (ranging from 1 m to 781 m) before going back underground. They do not return to sleep in a particular burrow, changing burrows frequently. The studied armadillos were diurnal, and spend 99.25% of the day underground, emerging only during the hottest period of the day (mid-afternoon). The southern naked-tailed armadillos should be classified as a subterranean species, rather than fossorial since they spent most of their time underground where foraging also takes place. Minimum densities of C. u. squamicaudis were estimated at 2.21 adults/km2. Gestation was estimated to last for 4 months. Parental care of a single young lasted on average 4 months. Niche overlap between E. sexcinctus and C. u. squamicaudis in the study area is minimal. [ABSTRACT FROM AUTHOR]

The giant armadillo (Priodontes maximus) is the largest living armadillo and is classified as Vulnerable by the International Union for Conservation of Nature. Little is known about the species biology and especially its reproduction. However, data such as the age at sexual maturity are employed for estimation of a species generation length, which is an important parameter for extinction risk assessment. Thus, the aim of this study is to estimate the age at sexual maturity for male P. maximus in the wild and to predict generation length for this species. During a long-term in situ study, eight male P. maximus were captured for reproductive evaluation considering both morphometric characteristics (e.g. body, penis and testes dimensions), and data on sperm production (assessed by electroejaculation). Based on observations of this study, it is estimated that male P. maximus reach sexual maturity at an age of 6.5–8 years. This is at least 5.5–7 years later than previously published. Consequently, generation length for P. maximus results in 11 years when applying standard formula including age at sexual maturity in males and an estimate of age at last reproduction of 20 years. However, the generation length is probably underestimated here as sexual maturity in females and age at last reproduction could be later than estimates used. Even these conservative estimates result in noticeable change for the timeframe used in extinction risk assessments for this species as it is 33 instead of 21 years. Thus, results from this study might affect the classification status of P. maximus particularly for regional assessments. [ABSTRACT FROM AUTHOR]

Mammals can show conspicuous behavioral responses to thermal variation, including changes in movement patterns. We used an integrative approach to understand how environmental temperature can drive the movement behavior of a mammal with low capacity for physiological thermoregulation, the giant anteater (Myrmecophaga tridactyla). We tracked 52 giant anteaters in 7 areas throughout the Brazilian savannah. We estimated the distance moved, area used, use of forest areas, and mean environmental temperature for each monitoring day of each individual. We modeled these data with Mixed Structural Equations — considering the possible interactions between our variables and controlling for sex and body mass. Giant anteaters reduced displacement and increased forest use with decreasing environmental temperature, probably because of their low body heat production. It is possible that they reduce distance moved and area used by reducing the duration of activity. With decreasing temperature, forest habitats become warmer than open ones, besides buffer rain and chilly winds. Reducing displacement and using forests are important strategies to reduce body heat loss and the energetic costs of thermoregulation. However, decreasing movement can limit food access and, consequently, fitness. Therefore, we highlight the importance of forests as thermal shelters. With increasing frequency and intensity of extreme weather events, we showed the need to preserve forest patches to offer suitable conditions for tropical mammals' behavioral thermoregulation. In this context, policies favoring deforestation on Brazilian territory are especially worrisome. Finally, we emphasize the need of integrative approaches to understand the complex interactions between organisms and the environment. [ABSTRACT FROM AUTHOR]

One of the benefits of modeling habitat selection for a given population is the ability to predict patterns in another population that inhabits an ecologically similar area. We studied habitat selection and home ranges of reintroduced and wild giant anteaters (Myrmecophaga tridactyla) in 2 South American wetlands (Iberá, Argentina, and Pantanal, Brazil). Nine reintroduced (Iberá) and 10 wild (Pantanal) adult animals were tracked via VHF and GPS between 2007 and 2015. We used resource selection functions to assess habitat selection for the wild anteaters from Pantanal. Generalized linear mixed models were constructed for resting and activity periods during both the wet and dry seasons. We then validated previous models built for reintroduced anteaters in Iberá using data from the wild animals from Pantanal. Habitat type (floodplain, grassland, open savanna, closed savanna, and forest) and distances to selected landscape traits were used as covariates. Locations near forests were positively selected in both populations. Selection of forests in Pantanal was less evident than in Iberá, probably due to the much higher availability of forests in the Brazilian site, with 38-53% of the landscape classified as good-to-high likelihood in Pantanal compared to only 4% in Iberá. Mean home-range size of males was larger in Iberá (32.50 ± 7.64 km2) than in Pantanal (14.07 ± 1.97 km2), whereas home-range sizes of females were similar in both areas (9.75 ± 1.74 km2 in Iberá; 9.62 ± 2.00 km2 in Pantanal). Results of this study suggest that model validation with geographically independent data is a useful tool to compare reintroduced and wild populations and to identify resources or landscape attributes that are important for a given species, even when these resources are abundant or highly available. [ABSTRACT FROM AUTHOR]