Pheomelanin-based colouration is correlated with indices of flying strategies in the barn owl

Resource polymorphism refers to individuals from the same population foraging in alternative habitats or on alternative food. Food specialization can be associated with adaptations such as colour polymorphism, with pale and dark colours conferring differential camouflage in different habitats. Pale and dark-reddish pheomelanic Barn Owls (Tyto alba) forage on different prey species in closed and open habitats, respectively. We show here that darker-reddish owls have heavier stomach content when found dead, and their 5th secondary wing feather is more deeply anchored inside the integument. These correlations suggest that their feathers bend less when flying, and that darker-reddish Barn Owls are able sustain more intense flying than their paler conspecifics

Relationship between diet and reproductive success in the Israeli barn owl

The effect of diet on barn owl (Tyto alba) breeding biology has been well studied in the temperate regions but not in the more arid Middle East. In temperate regions, barn owls are darker colored and mainly prey upon Cricetidae rodents, whereas in arid regions, they are lighter colored and prey to a larger degree upon Muridae rodents. In this study we analyzed the diet and breeding success of 261 barn owl pairs nesting in Israel. The reproductive success of barn owls declined from March to August, and fledged more young when they consumed a larger proportion of social voles (Microtus socialis guentheri). Although the diet of the lighter colored barn owls in Israel comprises more Muridae than that of the darker morphs in temperate regions, in both regions the number of barn owl young increases with an increased proportion of voles in the diet

Relationship between diet and reproductive success in the Israeli barn owl

The effect of diet on barn owl (Tyto alba) breeding biology has been well studied in the temperate regions but not in the more arid Middle East. In temperate regions, barn owls are darker colored and mainly prey upon Cricetidae rodents, whereas in arid regions, they are lighter colored and prey to a larger degree upon Muridae rodents. In this study we analyzed the diet and breeding success of 261 barn owl pairs nesting in Israel. The reproductive success of barn owls declined from March to August, and fledged more young when they consumed a larger proportion of social voles (Microtus socialis guentheri). Although the diet of the lighter colored barn owls in Israel comprises more Muridae than that of the darker morphs in temperate regions, in both regions the number of barn owl young increases with an increased proportion of voles in the diet

Conditional association between melanism and personality in Israeli barn owls

Capsule Boldness defines the extent to which animals are willing to take risks in the presence of a predator. Late, but not early, in the breeding season, Israeli nestling Barn Owls displaying larger black feather spots were more docile, feigned death longer and had a lower breathing rate when handled than smaller-spotted nestlings. Larger-spotted breeding females were less docile if heavy but more more docile if light. The covariation between personality (boldness vs. timid) and melanin-based colouration is therefore conditional on environmental factors

Fires can benefit plants by disrupting antagonistic interactions

Fire has a key role in the ecology and evolution of many ecosystems, yet its effects on plant–insect interactions are poorly understood. Because interacting species are likely to respond to fire differently, disruptions of the interactions are expected. We hypothesized that plants that regenerate after fire can benefit through the disruption of their antagonistic interactions. We expected stronger effects on interactions with specialist predators than with generalists. We studied two interactions between two Mediterranean plants (Ulex parviflorus, Asphodelus ramosus) and their specialist seed predators after large wildfires. In A. ramosus we also studied the generalist herbivores. We sampled the interactions in burned and adjacent unburned areas during 2 years by estimating seed predation, number of herbivores and fruit set. To assess the effect of the distance to unburned vegetation we sampled plots at two distance classes from the fire perimeter. Even 3 years after the fires, Ulex plants experienced lower seed damage by specialists in burned sites. The presence of herbivores on Asphodelus decreased in burned locations, and the variability in their presence was significantly related to fruit set. Generalist herbivores were unaffected. We show that plants can benefit from fire through the disruption of their antagonistic interactions with specialist seed predators for at least a few years. In environments with a long fire history, this effect might be one additional mechanism underlying the success of fire-adapted plants

Cascading Effects of Anthropogenic Excess Food for Predators on a Peri-Urban Population of an Endangered Ungulate

A major side effect of urbanization is the increased availability of food for wildlife in peri-urban areas. Most research has focused on highly adaptive exploiter species that thrive under such conditions, overlooking avoider species, which are often predated upon by exploiters. Moreover, peri-urban areas are often grazed by livestock, mainly to reduce the frequency and intensity of fires, a practice that can also adversely affect vulnerable wildlife species. We examined the long-term effects of excess food provided to discourage exploiter species, namely golden jackal (Canis aureus) and wild boar (Sus scrofa), from foraging on farmland and in human residencies. Both species prey on endangered mountain gazelles (Gazella gazella) in our peri-urban study area, which is nested within a mosaic of settlements and agricultural lands in Mediterranean Israel. Because the park is routinely subjected to seasonal cattle ranching, we included cattle stocking rate (mean ± SD: 51.77 ± 18.21 cow grazing days/ha) as an alternative factor, into our analysis. We used Generalized Linear Mixed Models to analyze an extensive dataset, comprising 724 surveys conducted over 17 years, and modeled gazelle encounter rates in response to excess food and cattle ranching, while controlling for environmental factors. Our results suggest that anthropogenic excess food through diversionary feeding led to decreasing gazelle densities, probably through increased predation by exploiter species. When diversionary feeding ceased after 12 years, gazelle encounter rates increased. We argue that this increase corresponds to population recovery, although it could be consistent with alternative mechanisms such as altered space-use and movement patterns. To conserve vulnerable and endangered wildlife species in urban and peri-urban areas, managers should reduce the availability of anthropogenic food for predators and scavengers. Furthermore, moderate cattle ranching (i.e., seasonal with low stocking rates) could mitigate potential adverse impacts of cattle ranching on mountain gazelle populations

Dietary composition and overlap between cattle and endangered mountain gazelle (Gazella gazella)

Israel’s Mediterranean biogeographical region is characterized by high habitat diversity and stark seasonal changes in forage composition, availability and quality. Managers of protected areas in this region advocate livestock ranching to mitigate fire risk and enhance conservation merits. However, competition between livestock and endangered, native ungulates in these areas might impair their functioning as refugia. We used fecal DNA metabarcoding to study the diets of native mountain gazelles (Gazella gazella) and domestic cattle (Bos taurus), in two nature reserves with distinct vegetation types (shrubland vs grassland), and during different seasons. Dietary overlap was ubiquitously low, and seasonal changes in the diets of both ungulates translated into differences in their dietary overlap, with the highest overlap found in grassland during winter. This generally low overlap may be attributed to the extreme differences in their body size or may also result from long-lasting sympatry of gazelles and cattle – first wild and later domesticated—shaping a robust dietary separation. Yet, since cattle biomass is typically much higher than gazelles’, a low dietary overlap in key food items of gazelles may result in their depletion which might negatively affect gazelles, especially during the fawning season and drought years. Our results highlight the need to cover diverse conditions when studying herbivore dietary composition and overlap

Predicting and controlling the reactivity of immune cell populations against cancer

Heterogeneous cell populations form an interconnected network that determine their collective output. One example of such a heterogeneous immune population is tumor-infiltrating lymphocytes (TILs), whose output can be measured in terms of its reactivity against tumors. While the degree of reactivity varies considerably between different TILs, ranging from null to a potent response, the underlying network that governs the reactivity is poorly understood. Here, we asked whether one can predict and even control this reactivity. To address this we measured the subpopulation compositions of 91 TILs surgically removed from 27 metastatic melanoma patients. Despite the large number of subpopulations compositions, we were able to computationally extract a simple set of subpopulation-based rules that accurately predict the degree of reactivity. This raised the conjecture of whether one could control reactivity of TILs by manipulating their subpopulation composition. Remarkably, by rationally enriching and depleting selected subsets of subpopulations, we were able to restore anti-tumor reactivity to nonreactive TILs. Altogether, this work describes a general framework for predicting and controlling the output of a cell mixture

Distribution and Extinction of Ungulates during the Holocene of the Southern Levant

BACKGROUND: The southern Levant (Israel, Palestinian Authority and Jordan) has been continuously and extensively populated by succeeding phases of human cultures for the past 15,000 years. The long human impact on the ancient landscape has had great ecological consequences, and has caused continuous and accelerating damage to the natural environment. The rich zooarchaeological data gathered at the area provide a unique opportunity to reconstruct spatial and temporal changes in wild species distribution, and correlate them with human demographic changes. METHODOLOGY: Zoo-archaeological data (382 animal bone assemblages from 190 archaeological sites) from various time periods, habitats and landscapes were compared. The bone assemblages were sorted into 12 major cultural periods. Distribution maps showing the presence of each ungulate species were established for each period. CONCLUSIONS: The first major ungulate extinction occurred during the local Iron Age (1,200-586 BCE), a period characterized by significant human population growth. During that time the last of the largest wild ungulates, the hartebeest (Alcelaphus buselaphus), aurochs (Bos primigenius) and the hippopotamus (Hippopotamus amphibius) became extinct, followed by a shrinking distribution of forest-dwelling cervids. A second major wave of extinction occurred only in the 19th and 20th centuries CE. Furthermore, a negative relationship was found between the average body mass of ungulate species that became extinct during the Holocene and their extinction date. It is thus very likely that the intensified human activity through habitat destruction and uncontrolled hunting were responsible for the two major waves of ungulate extinction in the southern Levant during the late Holocene