Litter loss triggers estrus in a nonsocial seasonal breeder

Sexually selected infanticide (SSI) is often presumed to be rare among seasonal breeders, because it would require a near immediate return to estrus after the loss of an entire litter during the mating season. We evaluated changes in reproductive strategies and the reproductive fate of females that experienced litter loss during the mating season in a seasonal breeder with strong evidence for SSI, the brown bear. First, we used a long-term demographic dataset (1986–2011) to document that a large majority of females (>91%) that lose their entire litter during the mating season in fact do enter estrus, mate, and give birth during the subsequent birthing season. Second, we used high-resolution movement data (2005–2011) to evaluate how females changed reproductive strategies after losing their entire litter during the mating season. We hypothesized that females would shift from the sedentary lifestyle typical for females with cubs-of-the-year to a roam-to-mate behavior typical for receptive females in no more than a few (~3) days after litter loss. We found that females with cubs-of-the-year moved at about 1/3 of the rate and in a less bimodal diurnal pattern than receptive females during the mating season. The probability of litter loss was positively related with movement rate, suggesting that being elusive and sedentary is a strategy to enhance cub survival rather than a relic of cub mobility itself. The movement patterns of receptive females and females after litter loss were indistinguishable within 1–2 days after the litter loss, and we illustrate that SSI can significantly reduce the female interbirth interval (50–85%). Our results suggest that SSI can also be advantageous for males in seasonally breeding mammals. We propose that infanticide as a male reproductive strategy is more prevalent among mammals with reproductive seasonality than observed or reported. Lactational anestrus, reproductive fate, reproductive strategy, sexual selection, sexually selected infanticide, Ursus arctos.publishedVersio

Differentiation and seasonality in suitable microsites of seed dispersal by an assemblage of omnivorous mammals

In endozoochorous seed dispersal, the ecological characteristics of each disperser determine the quantitative and qualitative aspects of the dispersal mechanism. To understand the role of different frugivores in multispecies seed dispersal networks, it is necessary to focus on the community structure and investigate where in the landscape seed deposition occurs. The aim of this research was to assess the quantitative and qualitative aspects of a mammalian endozoochorous seed dispersal network in a temperate forest ecosystem and identify the seasonal dispersal niche of each member of the assemblage. We hypothesized that differences among dispersers and seasons would occur in (H1) the proportion of scats that contain seeds, seed abundance in scats, and the number of seed species dispersed per scat, and in (H2) the probability of dispersing seeds to suitable microsites for germination of each species and seed abundance. We also hypothesized (H3) that the microhabitat variables of deposition sites would vary among dispersers, and (H4) that complementary structures would occur in terms of dispersers, dispersed species, and deposition sites. From summer (June–August) to autumn (September–November) in 2003 and 2004, we collected scats of five mammalian frugivorous species and recorded eight microhabitat variables at each deposition site in central Japan. We recorded the presence and number of seeds in scats and identified all seed at the species level. We considered a deposition site as suitable when the habitat type (interior forest, treefall gap, forest edge, and outside the forest) at a deposition site matched the microhabitat required for the for the dispersed species to germinate and survive as seedlings. A total of 341 scats containing seeds of 16 fleshy-fruited species were collected. Among these, 213 (62.5 %) scats were dispersed to suitable habitats (summer: 68.8 %, autumn: 54.8 %). We found that the seed abundance in the scat varied among dispersers and was higher in autumn (H1–2). The probability of dispersing seeds to suitable microsites switched among dispersers from summer to autumn (H2). The distinctive microhabitat variables and variation in microhabitat at deposition sites differed among dispersers across seasons (H3). Disperser-plant and disperser-deposition site networks were specialized and modular in structure compared to random networks during both seasons, but there was a less nested structure in summer compared to autumn (H4). The five mammal species showed differences and seasonality in seed dispersal niches. Because of these differences, these mammal species may play redundant and complementary roles in the seed dispersal network

Marking behavior of Andean bears in an Ecuadorian cloud forest : A pilot study

Very little is known about marking behavior of the endangered Andean bear (Tremarctos ornatus). Here, we present a first detailed description of Andean bear marking behavior obtained using camera traps. From November 2012 to April 2013, we inspected 16 bear trails in the Napo province of eastern Ecuador, and installed camera traps (n = 3) at marking sites to document their marking behavior. We obtained 22 video recordings of Andean bears, all of which were captured during daytime. Almost all recordings (n = 18) contained behavior associated with marking. Tree-rubbing was the main behavioral display at marking sites, and consisted of 4 common activities: (1) tree-sniffing, (2) rubbing the neck and/or shoulders, (3) rubbing the flanks, and (4) rubbing the back. Bears also claw-marked and urinated while rubbing trees. We only observed scent-marking from males. Consistent with other bear species, we suggest that Andean bears communicate intra-specifically through their marking behavior

Human shields mediate sexual conflict in a top predator - Data

Text file containing GPS reloaction data linked to spatial covariates and bear metadata. Note that the continuous variables are already scaled

Faecal spectroscopy: a practical tool to assess diet quality in an opportunistic omnivore

publishedVersio

Data from: Human shields mediate sexual conflict in a top predator

Selecting the right habitat in a risky landscape is crucial for an individual's survival and reproduction. In predator–prey systems, prey often can anticipate the habitat use of their main predator and may use protective associates (i.e. typically an apex predator) as shields against predation. Although never tested, such mechanisms should also evolve in systems in which sexual conflict affects offspring survival. Here, we assessed the relationship between offspring survival and habitat selection, as well as the use of protective associates, in a system in which sexually selected infanticide (SSI), rather than interspecific predation, affects offspring survival. We used the Scandinavian brown bear (Ursus arctos) population with SSI in a human-dominated landscape as our model system. Bears, especially adult males, generally avoid humans in our study system. We used resource selection functions to contrast habitat selection of GPS-collared mothers that were successful (i.e. surviving litters, n = 19) and unsuccessful (i.e. complete litter loss, n = 11) in keeping their young during the mating season (2005–2012). Habitat selection was indeed a predictor of litter survival. Successful mothers were more likely to use humans as protective associates, whereas unsuccessful mothers avoided humans. Our results suggest that principles of predator–prey and fear ecology theory (e.g. non-consumptive and cascading effects) can also be applied to the context of sexual conflict

Data_Archiving_JAE-2015-00663

Cub survival before (den emergence to mid-May), during (mid-May to mid-July), and after the mating season (mid-July to November) in brown bears in Sweden. Each line represents a litter. 'FemaleID' is the ID of the mother of the litter. Age indicates the age (years) of the mother. Status is the parity of the mother (primiparous or multiparous). Distance to the closest male killed is to the closest registered adult male killed within the 1.5 previous years. Timelag is whether the closest male was killed 0.5 or 1.5 years before the litter was born. The number of male shot are the number of registered adult male killed within the previous 1.5 years in a radius of 25km of a litter or between a radius of 25 to 80km of a litter. 'Population_density' is an index that approximate the number of bears within 1000 km² around the home range center of a litter. 'Food_index' is an index of the general food condition of the study population for each year

Faecal spectroscopy: a practical tool to assess diet quality in an opportunistic omnivore

publishedVersio

Human shields mediate sexual conflict in a top predator - main r code

Human shields mediate sexual conflict in a top predator - main r cod