Magpie in the context of "Urocissa"

The Eurasian magpie or common magpie (Pica pica) is a resident breeding bird throughout the northern part of the Eurasian continent. It is one of several birds in the crow family (corvids) designated magpies, and belongs to the Holarctic radiation of "monochrome" magpies. In Europe, "magpie" is used by English speakers as a synonym for the Eurasian magpie: the only other magpie in Europe is the Iberian magpie (Cyanopica cooki), which is limited to the Iberian Peninsula. Despite having a shared name and similar colouration, it is not closely related to the Australian magpie.

The Eurasian magpie is one of the most intelligent birds. The expansion of its nidopallium is approximately the same in its relative size as the brain of chimpanzees, gorillas, orangutans and humans. It is the only non-mammalian species known to pass the mirror test.

A bird nest is the spot in which a bird lays and incubates its eggs and raises its young. Although the term popularly refers to a specific structure made by the bird itself—such as the grassy cup nest of the American robin or Eurasian blackbird, or the elaborately woven hanging nest of the Montezuma oropendola or the village weaver—that is too restrictive a definition. For some species, a nest is simply a shallow depression made in sand; for others, it is the knot-hole left by a broken branch, a burrow dug into the ground, a chamber drilled into a tree, an enormous rotting pile of vegetation and earth, a shelf made of dried saliva or a mud dome with an entrance tunnel. Some birds, including magpies, have been observed building nests using anti-bird spikes. In some cases, these nests can contain up to 1,500 metal spikes. Magpies use the spikes to form a protective dome, which may help deter predators and safeguard their chicks, ironically using the spikes in a way that still serves their original purpose of keeping (other) birds away. The smallest bird nests are those of some hummingbirds, tiny cups which can be a mere 2 cm (0.8 in) across and 2–3 cm (0.8–1.2 in) high. At the other extreme, some nest mounds built by the dusky scrubfowl measure more than 11 m (36 ft) in diameter and stand nearly 5 m (16 ft) tall. The study of birds' nests is known as caliology or nidology.

Not all bird species build nests. Some species lay their eggs directly on the ground or rocky ledges, while brood parasites lay theirs in the nests of other birds, letting unwitting "foster parents" do the work of rearing the young. Although nests are primarily used for breeding, they may also be reused in the non-breeding season for roosting and some species build special dormitory nests or roost nests (or winter-nest) that are used only for roosting. Most birds build a new nest each year, though some refurbish their old nests. The large eyries (or aeries) of some eagles are platform nests that have been used and refurbished for several years. The Eurasian coot also reuses nesting sites, particularly in urban areas like the canals of Amsterdam, where nests made from plastic waste have formed stratified layers over decades. These layers, preserved due to the non-degradable nature of plastic, can be dated using expiration dates on food packaging found within them.

The difficulty of defining or measuring intelligence in non-human animals makes the subject difficult to study scientifically in birds. In general, birds have relatively large brains compared to their head size. Furthermore, bird brains have two-to-four times the neuron packing density of mammal brains, for higher overall efficiency. The visual and auditory senses are well developed in most species, though the tactile and olfactory senses are well realized only in a few groups. Birds communicate using visual signals as well as through the use of calls and song. The testing of intelligence in birds is therefore usually based on studying responses to sensory stimuli.

The corvids (ravens, crows, jays, magpies, etc.) and parrots are often considered the most intelligent birds, and are among the most intelligent animals in general. Pigeons, finches, chickens, and birds of prey have also been common subjects of intelligence studies.

Corvidae is a cosmopolitan family of oscine passerine birds that contains the crows, ravens, rooks, magpies, jackdaws, jays, treepies, choughs, and nutcrackers. In colloquial terms, the crow family is made up of corvids; currently 139 species are included. The genus Corvus containing 50 species makes up over a third of the entire family. The raven is the largest passerine bird.

Corvids display remarkable intelligence for animals of their size, and are among the most intelligent birds thus far studied. Specifically, members of the family have demonstrated self-awareness in mirror tests (Eurasian magpies) and tool-making ability (e.g. crows and rooks), skills which until recently were thought to be possessed only by humans and a few other mammals. Their total brain-to-body mass ratio is equal to that of non-human great apes and cetaceans, and only slightly lower than that of humans.

Pica (/ˈpaɪkə/ PY-kə) is the psychologically compulsive craving or consumption of objects that are not normally intended to be consumed. It is classified as an eating disorder but can also be the result of an existing mental disorder. The ingested or craved substance may be biological, natural, or manmade. The term was drawn directly from the medieval Latin word for magpie, a bird subject to much folklore regarding its opportunistic feeding behaviors.

According to the Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5), pica as a standalone eating disorder must persist for more than one month at an age when eating such objects is considered developmentally inappropriate, not part of culturally sanctioned practice, and sufficiently severe to warrant clinical attention. Pica may lead to intoxication in children, which can result in an impairment of both physical and mental development. In addition, it can cause surgical emergencies to address intestinal obstructions, as well as more subtle symptoms such as nutritional deficiencies, particularly iron deficiency, as well as parasitosis. Pica has been linked to other mental disorders. Stressors such as psychological trauma, maternal deprivation, family issues, parental neglect, pregnancy, and a disorganized family structure are risk factors for pica.