Large ‘apex’ predators influence ecosystems in profound ways, by limiting the density of their prey and controlling smaller ‘mesopredators’. The loss of apex predators from much of their range has lead to a global outbreak of mesopredators, a process known as ‘mesopredator release’ that increases predation pressure and diminishes biodiversity. While the classifications apex‐ and meso‐predator are fundamental to current ecological thinking, their definition has remained ambiguous. Trophic cascades theory has shown the importance of predation as a limit to population size for a variety of taxa (top–down control). The largest of predators however are unlikely to be limited in this fashion, and their densities are commonly assumed to be determined by the availability of their prey (bottom–up control). However, bottom–up regulation of apex predators is contradicted by many studies, particularly of non‐hunted populations. We offer an alternative view that apex predators are distinguishable by a capacity to limit their own population densities (self‐regulation). We tested this idea using a set of life‐history traits that could contribute to self‐regulation in the Carnivora, and found that an upper limit body mass of 34 kg (corresponding with an average mass of 13–16 kg) marks a transition between extrinsically‐ and self‐regulated carnivores. Small carnivores share fast reproductive rates and development and higher densities. Large carnivores share slow reproductive rates and development, extended parental care, sparsely populated territories, and a propensity towards infanticide, reproductive suppression, alloparental care and cooperative hunting. We discuss how the expression of traits that contribute to self‐regulation (e.g. reproductive suppression) depends on social stability, and highlight the importance of studying predator–prey dynamics in the absence of predator persecution. Self‐regulation in large carnivores may ensure that the largest and the fiercest do not overexploit their resources.

Agricultural farming is a major consumer of global arable lands and has a direct effect on species decline through habitat destruction. However, agricultural endeavours can also evoke indirect threats that will result in behavioural modifications of indigenous species. In a desert ecosystem, where a political border led to a farming dichotomy between intensive cultivates in Israel and intact lands in Jordan, we compared the foraging behaviours and abundances of the red fox and two species of gerbils, close to and distant from farms, and during two moon phases. We estimated fox and gerbil foraging levels by track counts, and measured gerbil time allocation, vigilance and apprehension by the giving-up density method. While foxes were significantly more abundant and active at locations close to farms, gerbils were significantly more abundant and active at locations distant from farms. Moreover, the typical reduction in food consumption during full-moon nights was exhibited only at locations close to farms. These results could suggest that indicators of predation risk, such as illumination intensity or distance to cover, are not universal, and their effectiveness may depend indirectly on anthropogenic activities, such as agricultural farming. The results could also suggest that although intensive agricultural endeavours benefit foxes, they might increase the predatory pressure on gerbils in addition to the already known effects of habitat loss. Therefore, agriculture acts as a double-edged sword by reducing natural habitats, while at the same time changing the predator-prey natural balance.

The locomotor activity pattern of the blind mole rat Spalax ehrenbergi was determined in its natural habitat by means of a radiotelemetric device. Twelve adult mole rats were fitted with radiotelemetric transmitters (9 during winter and 3 during summer) and tracked for 5 noncontinuous days during which air and soil temperatures were measured. Mole rats were found to have a diurnal monophasic locomotor activity pattern with activity peaks from 08:00 to 13:00 and from 11:00 to 19:00 during summer and winter, respectively. Activity periods were punctuated by several rest breaks and, conversely, rest periods were interrupted by short spells of activity. Duration of activity was 6.6 ± 0.4 h (mean ± SD) in summer and 7.9 ± 2.3 h in winter. In the laboratory, mole rats were found to entrain their activity, under constant dim light, to a single daily 20-s light pulse. Moreover, such a light pulse given only once every 3 days was found to provide a stimulus sufficient to entrain the mole rats' locomotor activity. We propose that brief light pulses perceived through the mole rats' rudimentary eyes while they are pushing excess soil out of the tunnel to the ground surface, are the main Zeitgeber that entrains their locomotor activity to the diurnal pattern. Air and soil temperatures are the secondary cues that finely tune the activity to the morning during summer and the late afternoon during winter.