Understanding the competition and coexistence of flagship carnivores is key to creating strategies for their conservation in the face of global carnivore declines. Although studies exploring the dynamics and competition between tigers (Panthera tigris) and leopards (P. pardus) span decades, there is a lack of understanding regarding the factors that influence their coexistence mechanisms on a broad scale, as well as the drivers determining their exploitative and interference competition. We gathered a comprehensive list of research papers among which 36 papers explored the interspecific interactions between tigers and leopards and tested the influence of biotic and abiotic factors on the coexistence mechanisms along three dimensions using multiple response variables regression models; we also tested the influence of ecological drivers determining the exploitative or interference competition between tigers and leopards. Elevation and ungulate density were the most important predictors in regulating the coexistence mechanisms. Tigers and leopards exhibited more positive relations/higher overlaps as elevation increased in the spatial niche. In addition, they showed a higher dietary overlap in the prey-rich regions. We determined that interference competition between tigers and leopards was less frequently observed in habitats with dense tree cover and homogeneous vegetation structures. Meanwhile, studies with multiple metrics would promote the detection of interference competition. Our study provides new insight into the competitive interactions and coexistence mechanisms of tigers and leopards on a broad scale. Policy-makers and managers should pay more attention to the factors of elevation, prey abundance, and habitat structures for the conservation of tigers and leopards.
A diverse sessile barnacle fauna from a Miocene shallow-water deposit at Dolnja Stara vas in Slovenia is described. It includes the first descriptions of early post settlement juveniles of Actinobalanus sloveniensis attached to mangrove leaves. These represent three distinct growth phases, the earliest being interpreted as being less than 24 h post settlement, the others being 1 to 2 days post settlement. An assessment of their taphonomy is provided. Associated adult balanomorphs are attached to a variety of organic substrates, including mangrove leaves and branches, fragments of the conifers? Taxodioxylon, Carapoxylon, pine cones, molluscs, and cetacean bones. The barnacles include A. sloveniensis, Amphibalanus venustus, and Perforatus perforatus—many with opercula retained within the shells. A. venustus retains some of the original shell color. This is the second record of barnacle–plant associations from the Central Paratethys from Kamnik and Trbovlje. The paleoecology and paleogeography of the site are discussed.
The study of the relationship between animal stress and personality for free-ranging animals is limited and provides contrasting results. The perception of stressors by an individual may vary due to its personality, and certain personality traits may help individuals to better cope with them. Using non-invasive infrared thermography (IRT), we investigated the link between physiological and behavioral components expressed during an acute stress event by free-ranging Fremont's squirrels (Tamiasciurus fremonti). We expected that, during the acute stress event of being approached by the researcher, individuals that showed a fast pace-of-life syndrome (bolder, more active, and less social/more aggressive) based on an arena test would exhibit stronger sympathetic-adrenal-medullary system reactivity showing a more intense stress-induced hyperthermia (high core body temperature and low peripheral temperature) than individuals with a slow pace of life (shy, less active, and more social). We successfully employed IRT technology to images of Fremont's squirrels with identification of the individuals’ body parts (eye, nose, ear, hind foot). However, we found no support for our hypothesis. Squirrels’ body surface temperatures told us more about a squirrel's external environment and less about the thermal state of the body in that environment following a stressful event. Further studies need to assess how to make IRT effective and efficient in the field and improve its performance in studying the relationships between physiology and personality in wildlife.
Globally, grassland degradation is an acute ecological problem. In alpine grassland on the Tibetan Plateau, increased densities of various small mammals in degraded grassland are assumed to intensify the degradation process and these mammals are subject to lethal control. However, whether the negative impact of small mammals is solely a result of population size or also a result of activity and behavior has not been tested. In this study, we use plateau pika as a model to compare population size, core area of colony, and the number of burrow entrances and latrines between lightly and severely degraded grassland. We test whether the alleged contribution of pika to grassland degradation is a result of increased population size or increased burrowing activities of individuals in response to lower food abundance. We found that grassland degradation resulted in lower plant species richness, plant height, and biomass. Furthermore, the overall population size of pika was not significantly affected by location in lightly and severely degraded grassland. However, pika core areas in severely grassland degradation were significantly larger and had significantly higher densities of burrows and latrines. Our study provides convincing evidence that habitat-induced changes in the behavior of small, burrowing mammals, such as pika, can exacerbate grassland degradation. This finding has significant implications for managing small mammals and restoring degraded grassland ecosystems.
Examples of predator–prey interactions in which flies rob ants are uncommon. To date, this behavior has only been recorded in the genus Bengalia Robineau-Desvoidy (Bengaliinae, Diptera, Calliphoridae). These predatory flies ambush ants, and rob them of the food or offspring that they are carrying. However, because of the rarity of this behavior, the reasons and consequences (evolutionary advantages) are unknown, and indeed, the behavior has been sometimes considered anecdotal. In this study, we employed field investigations and behavioral analyses to investigate whether the sex of the fly Bengalia varicolor, or the weight and quality of the food carried by Pheidole nodus ants influenced fly–ant interactions in their natural habitats. We show that food weight and quality influenced the behavior of B. varicolor independent of the fly's sex. Robbing behavior by the flies was more successful when the food robbed was of high-quality and light in weight. Furthermore, the weight of the food robbed modulated the escape distance the flies could carry it. This then may affect the food quality and weight transported by the ants. This is a novel example of deciphering the relationship between highwayman flies and their ant victims. Given the widespread distribution of Bengalia flies, we suggest that such interspecific predator–prey encounters may shape the robbery interactions and the carrying behavior of further ant species in nature.
Stacking is the process of overlaying inferred species potential distributions for multiple species based on outputs of bioclimatic envelope models (BEMs). The approach can be used to investigate patterns and processes of species richness. If data limitations on individual species distributions are inevitable, but how do they affect inferences of patterns and processes of species richness? We investigate the influence of different data sources on estimated species richness gradients in China. We fitted BEMs using species distributions data for 334 bird species obtained from (1) global range maps, (2) regional checklists, (3) museum records and surveys, and (4) citizen science data using presence-only (Mahalanobis distance), presence-background (MAXENT), and presence–absence (GAM and BRT) BEMs. Individual species predictions were stacked to generate species richness gradients. Here, we show that different data sources and BEMs can generate spatially varying gradients of species richness. The environmental predictors that best explained species distributions also differed between data sources. Models using citizen-based data had the highest accuracy, whereas those using range data had the lowest accuracy. Potential richness patterns estimated by GAM and BRT models were robust to data uncertainty. When multiple data sets exist for the same region and taxa, we advise that explicit treatments of uncertainty, such as sensitivity analyses of the input data, should be conducted during the process of modeling.
Infant call structure should have evolved to elicit maximum maternal attention and investment. Neonates of giant pandas produce three types of vocalizations reported to be vitally important in the context of mother–infant communications. However, how cubs, 0–15 days old, communicate with their mothers to elicit maternal care remains unknown. We analyzed 12 different call parameters of 3475 squawks, 1355 squalls, and 491 croaks from 11 captive giant panda (Ailuropoda melanoleuca) neonates from age 0 to 15 days. In playback experiments, we also tested whether mothers could detect ultrasound. Our results show that neonates use broadband calls with ultrasonic frequencies up to 65 kHz to convey information about their physiological needs and to attract maternal care. In playback experiments, we tested if mothers reacted differently to broadband calls (BBC) than to artificially altered calls that included only frequencies <20 kHz (AUDC) or calls that included only frequencies >20 kHz (USC). Playback confirmed that, although adult females responded significantly less often to USC, BBC than to or AUDC, they could detect USC, BBC and generally made appropriate behavioral responses, indicating a potential benefit for neonates to utilize ultrasonic and broadband frequencies. Our findings provide a new insight into mother–infant communication in giant pandas and will be helpful for reducing the mortality of cubs, younger than 1 month old, in captivity.
Food and predators are the most noteworthy objects for the basic survival of wild animals, and both are often deviant in both spatial and temporal domains and quickly attract an animal's attention. Although stimulus-specific adaptation (SSA) is considered a potential neural basis of salient sound detection in the temporal domain, related research on visual SSA is limited and its relationship with temporal saliency is uncertain. The avian nucleus isthmi pars magnocellularis (Imc), which is central to midbrain selective attention network, is an ideal site to investigate the neural correlate of visual SSA and detection of a salient object in the time domain. Here, the constant order paradigm was applied to explore the visual SSA in the Imc of pigeons. The results showed that the firing rates of Imc neurons gradually decrease with repetitions of motion in the same direction, but recover when a motion in a deviant direction is presented, implying visual SSA to the direction of a moving object. Furthermore, enhanced response for an object moving in other directions that were not presented ever in the paradigm is also observed. To verify the neural mechanism underlying these phenomena, we introduced a neural computation model involving a recoverable synaptic change with a “center-surround” pattern to reproduce the visual SSA and temporal saliency for the moving object. These results suggest that the Imc produces visual SSA to motion direction, allowing temporal salient object detection, which may facilitate the detection of the sudden appearance of a predator.
Understanding the habitat shifting pattern is a prerequisite for implementing in situ conservation of migratory species. Spotted seals (Phoca largha) inhabiting the Yellow Sea ecoregion (YSE) comprise a small population with independent genes and represent a charismatic flagship species in this region. However, this population has declined by 80% since the 1940s, and increased support from the countries around the YSE is urgently needed to address the potential local extinction risk. A time-series niche model and life-history weighted systematic conservation planning were designed on the basis of a satellite beacon tracking survey (2010–2020) of the YSE population. The results showed clustering and spreading shifting patterns during the breeding and migratory seasons, respectively. The closed-loop migration route formed in the YSE indicated that this population might be geographically isolated from populations in other breeding areas around the world. The conservation priority area (CPA), with an area of 19 632 km2 (3.58% of the total YSE area), was the most effective response to the potential in situ risk. However, nearly 80% of the CPA was exposed outside the existing marine protected areas (MPAs). Future establishment of MPAs in China should strategically consider the conservation gap identified herein, and it is recommended for Korea's closed fishing season to be spatially set in the western Korean Peninsula from May to August. This study also exemplified that the lack of temporal information would lead to the dislocation of niche modeling for migratory species represented by spotted seals. Attention should be paid to protecting small and migratory populations in marine biodiversity conservation planning.
Habitat restoration is an effective method for improving landscape connectivity, which can reduce habitat fragmentation. Maintaining landscape connectivity could promote connections between habitat, which is extremely essential to preserve gene flow and population viability. This study proposes a methodological framework to analyze landscape connectivity for Asian elephant habitat conservation, aiming to provide practical options for reducing habitat fragmentation and improving habitat connectivity. Our approach involved combining a species distribution model using MaxEnt and landscape functional connectivity models using graph theory to assess the impact on connectivity improvement via farmland/plantation restoration as habitat. The results showed that: (1) there were 119 suitable habitat patches of Asian elephant covering a total area of 1952.41 km2. (2) The connectivity between habitats improved significantly after vegetation restoration and the gain first decreased and then increased with the increase of dispersal distance. (3) The first few new habitat patches that were identified played an important role in improving connectivity, and the variation rate of connectivity gradually leveled off as the number of new habitats increased. (4) Prioritization of the 25 best new habitat patches increased connectivity from 0.54% to 5.59% as the dispersal distance increased and mainly was located between two Asian elephant distribution regions and two components. Establishment of new habitat patches was effective for improving or restoring connectivity. Our findings can be used as guidance for improving the studied fragmented Asian elephant habitats, and they can also be used as a reference for the habitat restoration of other endangered species heavily affected by habitat fragmentation.