Tit (bird)

• 1. Introduction

  ›

  Tits, chickadees, and titmice belong to a single bird family called the Paridae, and they have quietly solved problems that stump most other animals. Somewhere in Japan, a small bird called the Japanese tit, known to scientists as Parus cinereus, strings together distinct calls in a sequence that researchers have compared to syntax and grammar in human language. These birds can tell each other to "scan surroundings" or to "approach", and the order of those messages changes what they mean. That is a level of communication that was once thought to belong only to people. How did birds this small, spread across so much of the planet, come to be so cognitively complex? What does their alarm call, their mating dance, and their habit of hammering open hazelnuts reveal about who they actually are? This is the story of a family that has settled every major landmass in the Northern Hemisphere, adapted to habitats from the British Isles to Japan to Alaska, and done it all while weighing as little as five grams.

• 2. A Name From Old English

  ›

  The word titmouse reaches back to the 14th century, built from two older pieces. The second part, mase, was the Old English name for this kind of bird, connected to the Proto-Germanic root maison and the modern Dutch mees and German Meise. The first part, tit, simply meant something small. For a few centuries the spelling was titmose, but during the 16th century the ending shifted under the influence of the word mouse, giving the spelling that has stuck ever since. In North America, the name chickadee took hold instead, drawn from the sound the birds actually make: a distinctive "chick-a-dee-dee-dee" alarm call that English-speaking settlers found impossible to ignore. On the other side of the world, emigrants to New Zealand encountered birds in the genus Petroica that looked superficially like tits and labeled them tomtits, even though those birds belong to a completely different family, the Petroicidae. The confusion was understandable; the resemblance was enough to fool people on the ground, even if the biology told a different story.

• 3. Built for the Trees

  ›

  Most members of the Paridae are small, stocky woodland birds with short, stout bills, and the family is extraordinarily consistent in its body plan. Three genera stand apart as exceptions: Sylviparus, Melanochlora, and Pseudopodoces. Among the rest, adult body length runs from 10 to 16 cm, and weight from 7 to 29 grams. When the three outlier genera are included, the range stretches from 9 to 21 cm and from 5 to 49 grams. The bills vary by diet: finer in species that eat mostly insects, stouter in those that rely more on seeds. Scientists have noted that tits appear to be evolving longer beaks over time, likely as a response to reaching food in the deeper cavities of bird feeders. The most unusual bill in the family belongs to Hume's ground tit of Tibet and the Himalayas, which is long and curved downward. The majority of variation across the family shows up in plumage, and particularly in color, with the rest of the body plan remaining strikingly uniform across dozens of species on multiple continents.

• 4. Language and Intelligence

  ›

  After the corvids, which include crows and jays, and after the parrots, the tits rank among the most intelligent birds on Earth. Their social lives depend on constant communication: they call so frequently that silence itself is a signal, used only when a predator is nearby or when a bird is trespassing on a rival's territory. The "chick-a-dee-dee" call of North American chickadees does more than name the species. The number of "dee" syllables appended at the end of the call scales with how dangerous the predator is. Studies on Parus cinereus have shown the encoding of specific commands within individual calls, with the ordering of those calls carrying compound meaning. Researchers have drawn an explicit parallel to syntax and grammar in human language. Perhaps the most striking finding concerns snake detection: these birds have been shown to form mental images when they hear the call that signals a snake is present. Before this research, that kind of imagery-based cognition was documented only in humans.

• 5. Eating and Caching

  ›

  Tits are generalist insectivores, and small defoliating caterpillars are a favored prey. Seeds and nuts take on greater importance in winter. One of the family's signature foraging moves is hanging, in which a bird works its way around a branch or twig from every angle, including upside down, to find food that a perched bird would miss. Where several tit species share the same woods, they divide the tree by size: larger species forage on the ground, medium-sized ones on the larger branches, and the smallest species on the outermost twigs. When a tit catches a large insect or a nut, it uses hold-hammering, pinning the item with its feet and striking it with the bill until it breaks open. With a hazelnut, that process takes around 20 minutes. Many genera also cache food, hiding reserves during winter to draw on later. That combination of flexibility, tool-like behavior, and memory for hidden stores underlies much of what makes this family so successful across such a wide range of climates.

• 6. Nesting and Raising Young

  ›

  Tits nest in cavities, usually in trees, and most species excavate their own nest sites. The rufous-vented tit of the Himalayas typically lays two eggs per clutch, while the European blue tit regularly lays 10 to 14. Under favorable conditions, the blue tit has produced as many as 19 eggs in a single clutch, a record for any altricial bird in the world. Most tits raise more than one brood per year, a strategy shaped by the demands of life in the Holarctic, where winters are severe, or in tropical Africa, where conditions can be so erratic that a single pair may be unable to find enough food to raise even one chick, and in drought years breeding may not be attempted at all. The blue tit stands out as the only typically polygynous species in the family; all others are generally monogamous. Many African tit species and the ground-dwelling Pseudopodoces are cooperative breeders, enlisting additional birds to help raise young. Even pair-breeding species tend to stay in stable flocks through the nonbreeding season, maintaining social bonds that carry across the annual cycle. Courtship feeding, where a male brings food to his mate, is common in pair-breeding tits and helps cover the energy cost of producing a large clutch.

• 7. A Changing Family Tree

  ›

  The classification of the Paridae has shifted considerably in recent decades. As recently as the mid-1990s, most species were lumped into the genus Parus, with only four genera, Pseudopodoces, Baeolophus, Melanochlora, and Sylviparus, considered clearly distinct. Analysis of mitochondrial DNA, specifically the cytochrome b gene, showed that arrangement to be paraphyletic, meaning Parus as then defined did not form a natural group. The genus has since been restricted to the Parus major-Parus fasciiventer clade. In 2013, Ulf Johansson and collaborators published a molecular study that became the basis for the current understanding of how the family's 13 genera relate to each other. The checklist maintained by AviList now recognizes 62 species in those 13 genera. The Sibley-Ahlquist taxonomy had earlier proposed a much larger Paridae that included the penduline tits and long-tailed tits, but the long-tailed tits are now understood to be more distant relatives, and the yellow-browed tit and sultan tit may actually be further from the core family than the penduline tits are. Meanwhile, tits arrived in North America not once but twice, probably during the Early-Mid Pliocene. The ancestors of the genus Baeolophus came first, and the chickadees arrived somewhat later.