Sexual preference refers to an animal's tendency to choose either males or females as partners for courtship or mating. Although sexual preference is closely related to sexual attraction, sexual motivation, and the actual performance of sexual behavior, these aspects of sexuality do not necessarily coincide. For example, an animal may actively seek sexual stimulation without showing a clear preference for either sex. Conversely, an animal may prefer partners of a particular s

When faced with a wide variety of products, many people have experienced difficulty making a choice. As the number of options increases, making a decision can become more difficult, requiring more time to consider the alternatives and sometimes even leading people to abandon the purchase altogether. This phenomenon is known as choice overload. Schematic Diagram of the Experimental Setup（Image source：Hemingway, C. T et al. (2026).， CC BY 4.0 。） In the past, this phenomenon was

Body size often influences the outcome of competition among animals. Larger species may monopolize food, occupy preferred habitats or directly attack smaller competitors. In the Negev Desert of southern Israel, Rüppell's fox (Vulpes rueppellii) shares its habitat with just such a neighbour: the red fox (Vulpes vulpes). In this region, red foxes weigh about 3.5 kg on average, whereas Rüppell's foxes weigh only about 1.7 kg, making the red fox roughly twice as heavy. Under such

Feathers found in the nests of spotless starlings (Sturnus unicolor) may convey information that other members of the same species can interpret. A recent study found that nests containing feathers experienced lower rates of conspecific brood parasitism. Conspecific brood parasitism is a reproductive tactic in which some females lay eggs in the nests of other females of the same species, leaving the hosts to incubate the eggs and rear the resulting nestlings. Because spotless

South America is home to a group of small, spotted and rosetted cats in the genus Leopardus whose taxonomy has puzzled researchers for decades. These cats are remarkably similar in appearance, with differences among populations often limited to subtle variations in body proportions, coat color, and marking patterns. The northern tiger cat (Leopardus tigrinus) has been particularly difficult to classify. The species was named as early as 1775, yet its original description was

Every New Year's Eve, fireworks fill the night with intense noise and light for only a few hours, yet their effects on roosting birds may persist far longer. Urban birds routinely encounter vehicles, human activity and a wide range of background noise, but sudden explosive sounds can still represent a very different form of disturbance. One study followed birds along the River Rhine in Basel, Switzerland, over three consecutive winters. The study site contained a long-establi

Ciliates (Ciliophora) are unicellular organisms, most of which can live freely in aquatic environments. Mobilid ciliates, however, have tied their life histories closely to animal hosts. They commonly inhabit the body surface or gills of aquatic animals, including fishes, mollusks, annelids, and crustaceans, attaching themselves to host tissues by means of an adhesive disc on the aboral side. At the center of the adhesive disc is a ring of specialized denticles that helps anc

Sloths spend much of their day in trees, often moving with their bodies suspended beneath branches while alternately hooking their limbs onto supports ahead of them. In most quadrupedal animals, the limbs primarily bear the forces generated as body weight presses downward against the ground. Sloths frequently experience a very different mechanical situation: their limbs must support the body's weight while it hangs below the point of attachment for prolonged periods. What fea

Nestlings confined to a nest, unable to fly or make a rapid escape, have very few options when a predator enters. Eurasian roller (Coracias garrulus) nestlings, however, have developed an unusual response. When strongly disturbed, they regurgitate an odorous orange liquid from their mouths. Ornithologists had observed this behavior before, but it remained unclear whether the vomit was simply a physiological response to distress or served a specific function. Eurasian roller (

For patients with respiratory failure, maintaining adequate oxygen levels in the blood is one of the most urgent priorities in life-saving care. Mechanical ventilation can be used to support pulmonary gas exchange, while patients with extremely severe respiratory failure may require extracorporeal membrane oxygenation (ECMO). Yet some animals have evolved an unusual survival strategy: when oxygen becomes scarce, they can absorb oxygen through their intestines. This led a Japa