Today we'd like to discuss a term that describes two related species or populations that exist in the same area: sympatry. Sympatry can refer to almost any kind of species or populations, but for this discussion we will focus on examples that include birds.
Species that are sympatric live in the same habitat, encounter each other frequently, and may share breeding or feeding locations. Interbreeding between species may occur.
Sympatric species do not necessarily share resources in this mutually beneficial way. The Great Spotted Cuckoo and its parasitic host species the Eurasian Magie are also considered to be sympatric. Cuckoos are brood parasites to their neighbors the magpies.
Sympatry is one of four terms used to describe how species (or populations) relate to each other. Species that exist in adjacent locations are parapatric. Species that are separated can be either peripatric or allopatric.
Today we'd like to share with you the meaning of the term altricial, especially as it relates to birds. It is the opposite of a term we shared earlier on the blog: precocial. Let's learn about what it means to be altricial!
The term altricial comes from the Latin alere, which means "to nurse, to rear, or to nourish." An altricial species is one in which the newly hatched or born young need to be cared for by their parents for an amount of time. While a precocial animal may be mobile and relatively independent within days or even hours of being born or hatched, an altricial species must rely on its parents to survive for a period of weeks, months, or even years before it is independent.
In birds, this means youngsters come out of the egg almost completely naked. They are relatively immobile, needing to stay in their nest, and some have closed eyes as well.
While having helpless babies may seem to be a disadvantage, there are advantages to this breeding strategy. Altrical eggs are smaller, relatively speaking, than precocial eggs, resulting in less biological stress to mother birds. Precocial animals are born or hatched with brains relatively large compared to their body size, but don't grow much as they mature. Altricial species are born or hatched with smaller brains which grow as the animal matures. In general, altricial species therefore "have a wider skill set" when they reach full maturity.
Most songbirds have altricial young, as do owls, hawks, herons, and woodpeckers. Rodents, cats, dogs, and humans also have altricial young, which rely on their parents for the first few weeks or decades of life, depending on the species and individual young.
When most people think of owls, one of the facts that often comes up is that they are nocturnal. Nocturnal animals are most active during the night, sleeping by day. While most owl species are nocturnal, not all are. Adaptations found in nocturnal animals include enhanced eyesight, hearing, and sense of smell. Besides owls, other bird species known for being nocturnal include the Southern Brown Kiwi, the Kakapo, and the Common Nighthawk. Familiar nocturnal animals include bats, raccoons, and fireflies.
Diurnal animals are most active during the day, and sleep at night. For the most part, all animals first evolved to be diurnal. Nocturnal animals later evolved adaptations for being active at night in order to avoid predators and reduce competition with other species. Advanced color vision is an adaptation seen in diurnal animals. While most birds are diurnal, many species migrate at night, mostly to avoid predation. Animals known for being diurnal include most reptiles, pollinator insect species, and primates (including humans).
There are other terms to describe when animals are active:
Crepuscular animals are most active during twilight hours, around dawn and around dusk. Examples of crepuscular birds include the Barred Owl and Chimney Swift.
Cathemeral animals are active during spurts of time during the day and night. The activity is sporadic and occurs at irregular intervals. Cathermal animals are usually active during parts of both daytime and nighttime. Lions and some species of lemur are known for being cathermal.
Oology is the study of bird eggs. It also refers to the study of bird nests and breeding behavior. Oology can also refer to the hobby of egg collecting, which is illegal in many locations.
Early scientific ornithological study often involved collecting birds by shooting them to study their anatomy and plumage up close. It also involved the collection and study of their eggs. Scientists studying the difference between samples of Pergrine Falcon eggs over time were able to identify DDT usage as the cause of a decline in raptor populations in the 1960s and 1970s.
Egg collecting as a hobby remained popular as the scientific value of this type of study declined. This was extremely popular especially in the United Kingdom, though the hobby was denounced by the British Ornithologists' Union as early as 1922. Although UK laws have made the amateur hobby collection of eggs illegal since 1954, oologists continue to pursue the hobby by collecting eggs. Egg collecting is illegal in many other jurisdictions as well, including the United States.
Allopreening refers to one animal preening another. While preening and grooming are usually individual actions, in some species, birds or animals will preen one another. This occurs in birds as well as other classes of animal.
We previously mentioned allopreening when discussing vultures during Vulture Week in 2015. The post Glossary of Vulture Terms explained, in part, that "allopreening refers to social grooming between multiple individuals, often performed to strengthen social bonds."
Social bonds may not be the only reason that birds preen or groom one another. Allopreening is most common in species that tend to gather in large flocks. In these species, birds in frequent close proximity to each other are more likely to transfer parasites amongst the close-knit group. Allopreening in these species helps to keep pests like ticks under control.
Allopreening between mated pairs of birds occurs more often in species where both the male and female raise their offspring together. The preening ritual may help strengthen the longer-lasting bond. In mated pairs where the birds may be separated for a long period of time, allopreening is part of a greeting ritual. For example, this type of allopreening occurs when male and female penguins are reunited after a long incubation shift where one of the mates was feeding at sea for days or weeks.
Allopreening may also help to reduce conflict or tensions among large flocks or breeding colonies of birds. The social structure of the colony plays a large part in who receives preening and how much.
Some birds have fleshy growths hanging or protruding from the head or the neck. When these are a normal part of their anatomy, they are called caruncles.
Caruncles are often made of bare skin, though some may have a sparse covering of small feathers. They are usually bright in color, like the bright red comb of a domestic chicken.
Caruncles are thought to be ornamental in nature, found in male birds and used to attract mates, though caruncles are found in females of some species, too. Large bare patches of flapping skin may also be used to thermoregulate the bird, especially in warm climates.
Some caruncles have specific names depending on where they are found on the body.
Comb A comb or cockscomb is a caruncle that grows on the top of the head. Males and females of a species may both have a comb, but it is generally larger in male birds. Combs are found in domestic chickens, like the Faverolles, and related bird species.
Wattle A wattle is a caruncle that hangs from the head or the neck. Wattles come in a set of two; when one such growth is present, it is known as a dewlap. On the Wattled Crane, the wattles hang from the upper throat and are almost fully feathered. Another wattled bird named for this distinguishing feature is the Long-wattled Umbrellabird.
Snood A snood is a caruncle that hangs from the forehead, and can extend over the beak. These are found in both the Wild Turkey and domestic varieties. During courtship, the snood elongates and darkens in male birds.
The King Vulture has an unusual caruncle on its beak, which appears as an orange fleshy crest-like protuberance attached to the cere.