Purple Martin is a language all its own. Subadult, adult, SREH; these are all terms that are commonly used in the martin world, but those new to Purple Martins may feel a little lost. Here are some of the more commonly used terms and their definitions.
Aberrant: Term used to describe an atypical plumage, structural characteristic, or behavior in an animal or plant. Many martin landlords mistakenly believe that they have one or more Purple Martins that return to their colony sites, year after year, with aberrant white wing feathers. In reality, all Purple Martins have patches of white flank feathers that stick up conspicuously behind the wings during certain conditions of feature erection.
Accidental: Term used to describe a bird or bird species when it shows up outside of its normal range. The Purple Martin was recorded as an accidental species in the state of Alaska when it was collected there about several hundreds of miles north of its normal breeding range. In contrast, when it is observed in Alberta, it is not an accidental species, but rather a summer resident.
Accipiter: A genus of hawks characterized by having short, rounded wings, long tails, and long legs. In North America, there are three species - the Northern Goshawk, the Cooper's Hawk, and the Sharp-shinned Hawk. These raptors feed mostly on birds and are therefore, superbly adapted for the speed and agility necessary to outmaneuver and catch such fast-moving prey. Although all three species of Accipiter hawk are known to prey on Purple Martins, should you witness a daytime attack on your martins by a hawk, it most likely was perpetrated by the Cooper's or the Sharp-shinned Hawk
Adaptation: In evolutionary biology, any physical structure, physiological process, or behavioral pattern that makes an organism more fit to survive and reproduce in its environment. The somewhat-stiffened tail and long curved toenails of Purple Martins are structural adaptations enabling them to cling vertically to the trunks of trees, just as woodpeckers do. Before native American Indians offered gourds to martins for nesting, and before the early colonists offered martins houses, Purple Martins nested almost exclusively in old nest holes excavated in trees by woodpeckers. Today, tree-nesting martins can only be found in western North America, in Arizona, New Mexico, Colorado, Utah, California, Oregon, Washington, British Columbia, and Mexico.
Addled: An egg that has become rotten or the living contents of which have died or been destroyed. Purple Martins commonly roll their addled eggs out of their nest cups into the nest periphery, or out onto the porches of their houses.
Adult: The term for birds in an age class older than that of the subadults. Purple Martins are not considered adults until two years after their hatching year. See "SY," "ASY," and "subadult."
Aerial Insectivore: An animal that feeds on insects caught while it and the insects are in flight. Because the Purple Martin is anaerial insectivore, it is susceptible to starvation during the types of prolonged weather conditions that prevent the flight of insects, such as snow, high winds, cold temperatures, and/or heavy rains.
Air Sacs: The thin-walled sacs extending from the lung bronchi of birds, which fill much of their body cavities. Their function is to increase respiratory volume and efficiency, and also to decrease body weight, adaptations that help make flight possible. In some highly-aerial birds, such as frigatebirds, the air sacs extend even into the outermost hollows of the wing bones.
Albinism: An abnormal lack of pigment in animals that results in white or whitish external features. The feathers of total albinos are completely white, while partial albinos have white feathering in only some areas. Total albinos have pink irises because blood vessels at the surface of the eyes become visible in the absence of other pigments. Most albinos are the result of a genetic abnormality, are present at birth, and can be passed on to offspring. Albinism is not extremely rare in Purple Martins - every year a few fledglings are reported somewhere, but they rarely survive their first year of life because they are harassed so severely by other martins.
Albumen: The gelatinous "white" of a bird's egg, whose function is to cushion and protect the yolk.
Altricial: Term used to describe young birds that are totally helpless (usually featherless, with eyes closed, and totally dependent on their parents) for a period after hatching. Contrast this with precocial young. At hatching, Purple Martin nestlings are altricial. Their eyes don't open until they are about 8 days old, they don't get a covering of body feathers until about 12 days of age, and they are unable to keep their own body temperatures up without the brooding of their parents until they are about 15 to 20 days old.
Alula: A small group of feathers attached to the first "finger" (at the bend) of the wing. Their function is to reduce turbulence and drag, and also assist with breaking and steering. Purple Martins have three alula feathers on each wing.
Apteria: Areas of a bird's skin from which no contour feathers grow. Apteria are sometimes covered by down feathers. People are often surprised to learn that Purple Martin's have apteria, since they appear to be completely feather covered, but this is because the feathers overlap these naked areas of skin.
ASY: Bird banding terminology for "After second year." This is a bird in its third (or greater) calendar year of life. ASY Purple Martins are distinguished by having an adult plumages, which they acquire in Brazil during their second winter there. See "adult," "subadult," and "SY."
Auriculars: The group of feathers that cover a bird's ear openings near the center of its "cheeks." They are also known as "ear coverts." In some bird species, the color or pattern of the auriculars are a field mark because they contrast with the rest of the face. However, in Purple Martins, the auriculars are indistinguishable with the rest of the face.
Aves: The Latin word for "bird" and also the name of the class of animals that consists exclusively of birds. Purple Martins are in the class Aves, the order Passeriformes, the family Hirundinidae, and the genus Progne.
Avian: Refers to birds. Feathers are a uniquely avian characteristic.
Aviary: Typically a large, enclosed facility where birds are kept in captivity, but are allowed to fly freely. In other words, a zoo for birds. For a number of years, the bird house, or aviary, at the National Zoo in Washington, DC, had an totally-albino Purple Martin in captivity.
Bachelor Male: A nonbreeding, male Purple Martin. Typically these are subadult males that were unable to attract a breeding female either because there aren’t enough females to go around (due to a skewed sex ratio) or because their claimed territory/cavity is not to any female’s liking. Bachelor male Purple Martins spend their summers trying to attract an unpaired female to their territories or nest, and also roaming around, visiting several local colony sites, hoping to attract a widowed female for a late nesting attempt.
Banding (Ringing-UK): The placement of a numbered metal band on the leg (or less commonly) wing of a bird in an effort to individualize the bird and thereby discover certain facts of its life history. To legally band Purple Martins (or any species of native wild bird) a person must have both state and federal bird banding permits.
Bathing Behavior: Purple Martins bathe in two, distinctly different, ways; splash bathing and rain bathing. Sometimes, when in the vicinity of a body of water, martins will fly low near the water, slow their airspeed into a stall, and repeatedly bounce off the surface, wetting their belly feathers. Then they fly back to the colony site, perch, and preen. This is splash bathing. But when there is a light rain, martins bathe by sitting out on wires, branches, or martin house perches, exposing themselves to the precipitation, while preening and shuffling their feathers. Based on the exuberance of the accompanied singing, martins seem to enjoy a light rain. This is rain bathing. Both types of bathing behavior are quite contagious in martins. Once one individual does it, many others do also. Martins do not bathe in bird baths.
Beak: Another name for a bird's bill. The beak of the Purple Martin is shiny black in color and has a shape typical of those species adapted to catching flying insects (i.e., broad and flattened).
Brooding: The behavior by parent birds of "sitting on" their nestlings in order to warm them, conceal them, or shade them. Because nestling Purple Martins are hatched in a state of complete nakedness and don't acquire a coat of feathers until they are about two weeks old, the adults spend a great deal of time brooding their young to keep them warm.
Brood Patch: An area of highly-vascularized, featherless skin that develops on the abdomen of birds during the breeding season that functions to facilitate heat transfer between the body of the incubating (or brooding) parent and the eggs (or nestlings). In martins, only the female develops a brood patch because she is the only parent with incubation responsibilities. A male martin will sit on the eggs and young, but he is only insulating them.
Brood Reduction: The strategy by which parent birds adapt their reproductive output to the current conditions of the environment. Most female birds lay the maximum number of eggs they can successfully raise in a good year, then sacrifice some of their eggs or young if conditions turn out to be less than ideal. Brood reduction can take many forms, from siblicide (siblings killing siblings), to kicking out selective egg, to subtle neglect of runts by parents. This strategy protects parents against losing their entire brood should conditions for rearing their young turn poor. This reduction of brood size is adaptive and actually helps parents fledge the maximum number of healthy young in any giving season.
Carnivore: An organism who has a diet comprised of living animals. Purple Martins are carnivores.
Carnivorous: The term used to describe the diet of an organism who eats living animals. Strictly speaking, Purple Martins arecarnivorous, since insects are animals. More specifically, Purple Martins are insectivorous. See "insectivorous."
Chicken Hawk: The colloquial name used to refer to any of the hawks presumed by the uneducated to habitually attack poultry yards. Although, all bird-eating hawks recognize an easy meal when they see one, and may occasionally take a chicken, none specialize on poultry.
Claw: The horny structure at the ends of the toes in birds, adapted for a whole host of functions, depending on the species. Purple Martins have long, decurved claws (toenails), which is an adaptation for clinging to vertical surfaces, such as at the entrances holes of the old woodpecker nest cavities they historically used for nesting sites (and still do in the western portion of their breeding range.)
Cloaca: The final enlargement of the digestive tract in birds, reptiles, amphibians, and many fish, through which solid wastes, urine, and the products of the reproductive system all pass prior to defecation, egg laying, or copulation. It opens just below the tail of birds and is also known as the vent. In humans, of course, the digestive passage is completely separate from the urinary and genital passages. When copulating, male Purple Martins merely contact the female's cloaca with theirs for as short a duration as a fraction of a second, which is long enough to successfully transfer their sperm to the female's reproductive tract.
Clutch: All of the eggs laid and incubated by a given bird during a single breeding attempt. The Purple Martin typically lays a clutchof 3 to 6, pure white eggs. In rare instances, a female will lay 7 or more eggs.
Clutch-initiation Date: The date on which the first egg of a clutch is laid. The earliest recorded clutch-initiation date for any martin nest studied at the PMCA's Edinboro, Pennsylvania research site is the 12th of May.
Colonial Nester: A bird species that nests in colonies. Purple Martins are colonial nesters.
Colony: A breeding aggregation of birds. A martin colony is just a random aggregation of unrelated birds attracted to a common breeding site. It is not an assemblage of birds that travels or functions as a group. Individual martins arrive in spring, and depart in late summer, independently of each other. At the colony site, individual martins aggressively compete with each other for nest cavities and mates. They in no way help or cooperate with each other. A person has a colony of Purple Martins (and is officially a "martin landlord") when they have two or more pairs breeding in the nesting compartments they offer.
Complete Paternity: Males who have not been cuckolded by their mates and are related, genetically, to 100% of the offspring hatched from the eggs in their nest, laid by the female to which they are paired. See "Partial Paternity" and "Zero Paternity."
Conservation: The wise use of natural resources, including birds and other organisms, whether for humanitarian reasons or to prevent the extinction of valuable and/or aesthetically desirable forms. The Purple Martin Conservation Association is a non-profit organization devoted entirely to the conservation of Purple Martins.
Contiguous Porches: Porches on certain martin house designs that connect adjacent cavities. Such designs are bad for martins in that they allow older nestlings from one compartment to wander into another compartment with younger nestlings to monopolize incoming food, thus starving their hosts. Such martin house designs also allow males to set up larger territories, thus excluding other breeders. Houses with many holes sharing a common porch have lower occupancy rates and fledging rates as a result. See "Porch Dividers."
Copulation: The physical act of mating. In the Purple Martin, as with most species of birds, copulation is accomplished by the male climbing onto (or landing on) the back of the female, then both birds making contact with their exposed cloacas. The male quickly ejaculates his semen and dismounts. In martins, the entire process lasts but a couple seconds. In birds, the average number of spermatozoa in a single ejaculation is about 3 billion, which is approximately 10 times that of human's. The sperm swim up the oviduct where the ova await fertilization. The sperm from a single copulation can remain alive in the oviduct and continue to fertilize ova for up to a month.
Courtship: An early stage in the breeding cycle, beginning with the male and female birds of a given species coming together, and ultimately leading to pair formation and copulation. In the Purple Martin, courtship begins when a male gives his advertising display to a prospective female. The male martin flies up in the air, dives to the house (or gourd), enters his compartment, turns and sings out of the entrance hole while simultaneously gaping to show his pink mouth lining. During early courtship, female martins choose the very best male/compartment combination they can. The "quality" of the compartment(s) a male is able to claim and defend from other males is an indicator to the female of his "quality" as a resource provider.
Coverts: A set of small feathers that covers other feathers. Purple Martins have tail, ear and wing coverts. The coverts help to smooth air flow over the wings and tail.
Crepuscular: In the context of animal behavior, the term means active in low levels of light, especially at dawn and dusk. Compare with "diurnal" and "nocturnal." No North American bird species is exclusively crepuscular, but some owls and nighthawks become active or conspicuous in the twilight hours before sunset and dawn. Purple Martins are crepuscular in the sense that the males fly up into the predawn sky to broadcast their dawnsong. They also forage up to thirty minutes past sunset when they have a hungry brood of young to feed.
Crissum: The triangular area of feathers on the undersurface of a bird between its vent (anal opening) and the base of its tail feathers. A martin landlord with a good pair of binoculars can tell which of his breeding female martins are subadults (yearlings) versus adults (older than a year) by getting a close look at the feathers of their crissum. Adult females usually have conspicuous dusky edgings to many of their crissum feathers; subadult females have a nearly pure white crissum.
Dawnsong: A song that adult (ASY) male martins emit in flight high above their breeding sites during the pre-dawn hours of spring. It's adaptive function is thought to be the attraction of nocturnally migrating subadult (SY) males and females to the colony site. By attracting more colony members, a dawnsinging male theoretically increases his opportunity of engaging in forced extrapair copulation, and therefore leaving more offspring during a single summer's breeding effort.
Delayed Plumage Maturation: The genetically programmed delay in adult plumage acquisition that is characteristic of several bird species. Both male and female Purple Martins have delayed plumage maturation and do not acquire their adult plumage until they are in their 3rd calendar year of life, which is their second potential breeding season. Because of this, yearling (i.e., subadult) males wear a very female-like plumage that confuses most martin landlords into thinking they have a shortage of males in their colonies or that two females successfully bred and raised young together.
Desert: Regions of the world that receive less than about 10 inches of rainfall a year. They are typically characterized by extremely hot daytime temperatures and have plant types adapted to low moisture conditions. Many people mistakenly believe you need to live near water to attract nesting martins. Not so. Purple Martins thrive in the arid Sonoran Desert of Arizona, where they nest in the well-insulated nest cavities excavated by the Gila Woodpecker and Gilded Flicker in the Saguaro cactus. Their only reliable source of water is the insects they consume.
Dispersal: The movement of a young bird from the site where it hatched to the site where it will breed. Natal dispersal is the permanent movement of young birds from their birth sites to their own breeding locations. The tendency to stay near one's birthplace - called philopatry - increases the probability of breeding with near relatives, even siblings, and thus increases the risk of inbreeding. Conversely, dispersal promotes outbreeding.
Diurnal: The term means "active during the day." Compare with "crepuscular" and "nocturnal." The Purple Martin, along with the vast majority of birds, are diurnal in their habits, although they do some nocturnal migrating.
Ectoparasite: An organism that lives on the outside of another organism to the detriment of the host. Because they are colonial cavity nesters (i.e., they nest in large groups where parasite transmission is enhanced), that exhibit strong year-to-year site fidelity (they reuse the same nests from year to year, which allows parasites to build up in their nests), Purple Martins are plagued by many kinds of ectoparasites. The list includes several kinds of body and head lice, nest mites, nasal mites, feather mites, fleas, blowflies, blackflies, and mosquitoes.
Egg Dumping: The deliberate laying of fertile eggs in another bird's nest. Through some highly-sophisticated genetic testing, Dr. Eugene Morton of the Smithsonian Institution recently discovered that Purple Martins occasionally brood parasitize neighboring martins by egg dumping in their nests. Egg dumping benefits the parasitic egg-layer, but costs the host egg-recipient in terms of wasted reproductive effort.
Eggshell: The hard, calcium shell, secreted by a bird's shell gland, that surrounds and protects its eggs (or ovums). The shell of a bird's egg is a marvelous thing. It has to be thin and porous enough to allow oxygen in and carbon dioxide out, strong enough not to break under the weight of the incubating parent(s), yet weak enough that a nestling can crack its way out at hatching time. Because Purple Martins lay their eggs in the darkness of tree cavities, their eggshells have never needed to evolve camouflaging colors or patterns, and are pure white like most cavity nesters.
Egg Tooth: A small, hard protuberance on the tip of the bill that develops in the embryos of all birds, and helps them break out (i.e. hatch) from the eggshell. Newly-hatched Purple Martins have a white, calcareous egg tooth on the upper tip of their beaks that falls off a few days after hatching.
Entomologist: A scientist who studies insects.
Exoskeleton: The hardened outer body layer of insects and other arthropods that functions both as a protective covering and as a skeletal attachment for muscles. For grit, Purple Martins feed their nestlings broken glass, metal fragments, quartz, sand, eggshell, and oystershell. This grit enables the nestling's gizzard to pulverize the armor-like exoskeletons of the beetles and other hard-bodied insects they are fed.
Fallout Shelter: A pole-mounted structure used to replace prematurely fledged nestling martins by martin landlords who don't have accessible martin housing, or who don't keep written records. Parent martins will only feed young that are up off the ground, safe from ground-dwelling predators. The best place for such young, however, is back in their own nest.
Fecal Sac: The white, gelatinous sac into which the wastes of nestling birds are excreted as an adaptation to help keep the nest more sanitary. Parent martins eat their nestlings' fecal sacs during the first few days of their lives. As the young grow, parent martins switch to carrying the sacs from the nest in their beaks and dropping them. Once the young are large enough, they defecate out the entrance hole.
Fertilization: In birds, as in mammals, this is the merging of the male's and the female's reproductive cells (sperm and ova). In birds, this takes place in the upper end of the female's oviduct, following copulation. See "copulation."
Fledge: The term used to describe the behavior by which a nestling bird leaves the nest under its own power. At the moment when a nestling martin fledges, it is usually escorted on its first flight by many of the other birds in the colony.
Fledgling: The term for a young bird from the time it first leaves the nest until it is independent of all parental care. Fledgling Purple Martins continue to be fed outside of the nest by their parents, for up to two weeks and typically return to their nest each night to sleep.
Folklore: Inaccurate scenarios passed down through the generations to help explain natural phenomenon. For instance, it is pure myth and folklore that migrating martin flocks send "scouts" ahead to find suitable housing, who then return south (in some cases, clear back to Brazil) to guide their colonies back. The truth is that scouts are just the first martins to arrive back in spring to the colony site they bred the previous year. Once they arrive, they do not leave, they stay put to defend their territories against later-arriving martins. The myth got started, no doubt, because as martins work their way homeward, they will use housing along the way as overnight "motels." As soon as the weather facilitates migration, they continue northward. Soon, however, the main wave of martin migration arrives at the "motel" site, giving the illusion that the scout returned with a flock.
Forced Extrapair Copulation: When a male animal forcibly copulates with a female other than his own, for the purpose of fertilizing her eggs, leaving her (and usually unknowingly, her mate) to raise his young. Adult male Purple Martins commonly engage in numerous forced extrapair copulations (FEPC's) with the mates of the subadult males breeding at their colony sites.
Gizzard: The highly muscular, second enlargement in a bird's digestive tract that, together with the first enlargement, functions like the human stomach
Gourd: The fruit of some plants in the family Cucurbitaceae, which have hard, durable, shells and are suitable for the fashioning of birdhouses after they have been properly dried. It was a popular custom among some tribes of Native American Indians, to hang up hollowed-out gourds for martins to nest in. Today, martins will also nest in plastic and ceramic gourds.
Grit: Small pieces of rock, shell, or other hard substances ingested by birds to assist the gizzard in the process of digestion. The muscular action of the gizzard, together with the abrasive action of the grit, help martins grind down the hard, chitinous, exoskeletons of the beetles, dragonflies, and other insects they eat. A gizzard with its grit is analogous in function to a mammal's mouth having teeth for the purpose of food pulverization.
Haematophagous: Means "blood eater." Several of the parasites that feed off the Purple Martin are haematophagous parasites. For instance, the blowflies, nest mites, blackflies, mosquitoes, and bedbugs.
Haemoproteus prognei: The Latin or scientific name of a microscopic parasite commonly found in the blood of Purple Martins.
Hallux: The first digit or "big toe" of a bird's foot. In the Purple Martin, as in most species of birds, the hallux is the hind toe, and opposes the three others that point forward. But not all families of birds have four toes and some groups lack a hallux altogether.
Hatch: The act of breaking out of the eggshell by the embryo. Purple Martin chicks hatch after about 15 to 17 days of incubation.
Hatching Success: Compare with "Nesting Success"
Home Range: The total area within which a bird inhabits while resident in a given place. Once established at a colony site, Purple Martins forage for food over a home range of approximately 5 to 10 square miles.
Hovering: A type of flight in which the bird remains stationary in midair, usually accompanied by the rapid beating of the wings. Purple Martins often hover in the airspace immediately in front of their nest compartments if for any reason they have to hesitate before landing. They also hover when in a strong headwind, they have a zero ground speed.
HY (Hatching Year): Bird banding terminology for "Hatching-year." This is a bird in its first calendar year of life. An HY-U is a fledgling (juvenile) Purple Martin of unknown sex.
Hyperphagic: A behavioral term meaning "eating a lot" used to describe what migratory birds become before their twice annual migration. Purple Martins become hyperphagic in late summer to fatten up before migration.
Incubation: The process by which parent birds heat their eggs by sitting on them, so that the young will develop and hatch. Incubation in the female martin does not begin until the next-to-the-last egg is laid. While the female martin sits on her eggs engaged in incubation, her mate will sometimes bring food to her at the nest.
Incubation Patch: See "brood patch."
Insectivore: An organism who has a diet comprised of insects. Purple Martins are insectivores.
Insectivorous: The term used to describe the diet of an organism who eats insects. The Venus Flytrap, the Purple Martin, the Indiana bat, the praying mantis, and the bullfrog, all have insectivorous diets.
Interspecific: Term that means "between two or more different species." The Purple Martin is suffering intense interspecific nest-site competition with both the introduced English House Sparrow and European Starling.
Intraspecific: Term that means "within one species." In the Purple Martin, intraspecific nest-site competition (which is competition between or among Purple Martins for nesting compartments) is one of the major causes of porch squabbles.
Introduced Birds: Birds that have been released by man into (and have subsequently become established in) regions where they are not native. The introduction of nearly all non-native (i.e. exotic) organisms is an ecologically harmful endeavor. In North America, both the European Starling and the English House Sparrow are introduced birds whose introduction and spread have been extremely detrimental to our native birds.
Iridescence: The rainbow-like play of colors exhibited by the feathers of certain bird species, caused by the scattering of light rays reflected from the structure of these unique feathers. The plumage of the adult male Purple Martin is ablaze with purplish-blue, iridescent feathers.
Iris: The part of an animal's eye that is pigmented, surrounding the dark pupil. It is made up of muscle fibers that control the size of the pupil and thus the amount of light allowed to enter the eye. The iris of Purple Martins is dark brown.
Kleptoparasitism: Stealing from one animal by another. Purple Martins are notorious kleptoparasites. During the absence of porch neighbors, Purple Martins sometimes enter adjacent compartments to kleptoparasitize nesting material, which they remove and then take back to their own nests. Older, pre-fledged martin nestlings also wander out of their compartments, onto the contiguous porches, and into neighboring nests, where they kleptoparasitize younger nestlings of the food brought in by their parents.
Latin (Scientific) Names: The Latin name of the Purple Martin is Progne subis. The Latin name of the martin's eastern subspecies is Progne subis subis, the desert subspecies, Progne subis hesperia, and the western mountainous race Progne subis arboricola. The nominate subis breeds throughout much of southern Canada, south through the eastern United States, west to Montana and central Texas, central parts of the Plains states, western Oklahoma, southern Florida, and the highlands of central Mexico. The race Hesperia replaces subis in Baja California, the lowlands of southern Arizona, western coastal Sonora and Tiburon Island. The race arboricola breeds in the western mountainous parts of North America.
Local Extinction: is the eradication of any geographically discrete population of individuals while others of the same species or subspecies survive elsewhere.
Martin Landlord: A person who supplies nesting houses or gourds for the Purple Martin and successfully attracts some. We estimate that nearly 1 million enthusiasts in North America put up housing for martins, unfortunately, not all of them succeed in becoming martin landlords.
Martin Scout: The very first, returning martin(s) observed in spring by the martin landlord at a colony site. Some landlords hold tight to the myth that scouts, after arriving, return to the south (or clear back to Brazil) to guide the rest of their colony back to the site. Actually, long-term banding studies reveal that in most cases, martin scouts are merely the oldest birds in the colony returning to their previous place of breeding. They do not return south to guide their "flocks" in. If there is an absence after their initial arrival, it is usually weather related (holed up, joined a communal cavity roost, or starved to death - there is no evidence of reverse migration in martins)., or they have moved on, using the site merely as an overnight "motel" on their way north.
Mate Guarding: The behavior of male organisms in which they stay constantly at the side of their mate during her fertile period so as to insure that only they are the fertilizer of her eggs. During the nest-building and egg-laying stages of the Purple Martin's nesting cycle, males closely mate guard their mate by accompanying and following her everywhere she goes. A male will accompany his mate to the eggshell tray and also land on the ground beside her while she selects every single piece of nest material that she carries to the nest.
Mate Guarding Intensity: Often measured as the percentage of female departures from the nest (before egglaying) during which the male escorted.
Migrant: Term applied to a animal that makes seasonal trips between breeding and wintering areas. The Purple Martin is the earliest tropical-wintering, migrant to return to the North American continent after spending the non-breeding season in South America.
Mobbing Behavior: The behavior of birds by which they vocally and physically harass their predators en masse in an attempt to drive them away from their breeding territories and nests. Purple Martins commonly mob hawks, cats, dogs and occasionally humans, that get too close to their nests or young. Mobbing takes the form of repeated, aerial dives to the intruder's head (missing by just inches), accompanied by harsh vocalizations.
Molt: The process by which a bird renews all or a part of its plumage, including the growth of new feathers as well as the loss of old. Purple Martins undergo a complete molt of their entire plumage once a year. Martin molt begins in late summer while they are still at their colony sites and is slowed or completely arrested during the southward migration. It is continued in earnest while on the wintering grounds.
Monogamous: Term to describe an animal species that pairs with or has only one mate at a time. Purple Martins are only monogamous in their pair-bonding behavior, which enables the sexes to equally share the duties of nest building and feeding of offspring. Compare with "Polygamous" and "Promiscuous."
Nest Fauna: The invertebrate inhabitants of bird's nests. Many of the creatures that live in bird's nests are harmful to the birds with which they cohabitate. If a martin landlord carefully examines the nest of a Purple Martin, they will discover a nest fauna comprised of the following ectoparasites: nest mites, fleas, bed bugs, and blowfly larvae. However, not all of the inhabitants of nests are harmful; some species are actually beneficial to their bird hosts by helping to clean the nest of feces and other organic debris, and by eating or parasitizing the bird parasites.
Nesting Success: The number of nesting attempts that succeed in fledging at least one nestling. Compare with "Fledging Success" and "Hatching Success."
Nestling: The term for a young bird from the time it hatches until it leaves the nest. The nestling period of the Purple Martin lasts about 26 to 34 days.
Nit: The egg of a louse or other parasitic insect. Louse nits can be seen on the head feathers of most martins and appear as tiny, white capsules. The lice that parasitize Purple Martins spend their entire life cycle on the birds and therefore, travel with them to Brazil and back each year, nestled among their feathers. Martins frequently engage in head scratching to relieve the irritation cause by the lice crawling there. Bird lice often concentrate on the head area of their hosts because both they and their nits are safe from visual "nit picking" there.
Nocturnal: The term means "active at night." Compare with "diurnal" and "crepuscular." During the breeding season and while on their wintering grounds, Purple Martins sleep at night. But during certain parts of their migration they are known to be nocturnal migrants.
Nostrils: As in humans, birds have paired, external openings to their respiratory systems known as nostrils (or nares). They open into passages in the skull and ultimately lead to the windpipe (trachea). Purple Martins have tiny parasites, known as nasal mites, that live and crawl around in their nostrils.
Oil Gland: A small, usually bilobated organ located above the tail at the base of the rump in most species of bird. It contains an oily substance that is secreted via a duct through an external opening at the surface of the skin. It is sometimes called the "uropygial gland" or "preen gland." Bird species with an oil gland, such as Purple Martins, repeatedly press oil from it with their bills, then spread it over the feathers during preening. When applied to the feathers, preen oil aids insulation and waterproofing, and maintains feather pliability. One investigator has shown that, when activated by the sun on the feathers, the oil produces vitamin D, which is absorbed through the skin and is believed to prevent the development of rickets in birds.
Ornithology: The scientific study of bird life. Most North American universities offer a course in Ornithology for their students who major in biology or zoology. If a person makes his or her living in the study or management of wild birds, or teaching others about birds, he or she would be called an ornithologist.
Parasite: An organism that lives with, and obtains food from, another organism, usually to the detriment of the latter. Nestling martins have their feathers and skin eaten, and their blood sucked, by the following parasites: fleas, lice, nest mites, bed bugs, feather mites, blackflies, louse flies, mosquitoes, and blowfly larvae. See "ectoparasite."
Parasite Load: The number of parasites living in, or on, a host. The greater the number of parasites, the heavier the parasite load is said to be. Purple Martins reusing old nests, living in larger groups, or suffering ill health or malnutrition, tend to have higherparasite loads than those who don't.
Parasiticide: A chemical or agent used to kill or repel parasites.
Partial Paternity: Males who have been cuckolded by their mates and are related, genetically, to only one or more (but not all) of the offspring hatched from the eggs in their nest, laid by the female to which they are paired. See "Complete Paternity" and "Zero Paternity."
Permanent Resident: A species of bird that both breeds and winters in the same region. The introduced European Starling and English House Sparrow are both permanent residents throughout most of North America, which gives them a competitive advantage over the Purple Martin, a highly migratory species.
Perspiration: Unlike humans, birds do not regulate their body temperature with dermal sweat glands that secrete perspiration. Instead, they thermoregulate by giving off excess heat in the form of water vapor, mainly by panting. On really hot days, martins sit with their beaks agape (they are panting to facilitate water vapor loss from their mouth linings), in an effort to cool off. When martin nestlings get too hot (especially those being reared in uninsulated housing), they will spread their mouths fully open.
Piracy: The stealing of food (or nesting material) from one bird by another. See "kleptoparasitism." Parent martins are known to steal nesting material from other martins (both in the air and out of their nesting compartments). They also have been observed stealing prey out the beaks of other martins, and occasionally even Chimney Swifts. Both nestling and fledgling martins will enter neighboring martin house compartments (where there are smaller nestlings) to pirate incoming food from their "host's" unsuspecting parents. The con works because parent martins don't recognize their own young until fledging age.
Play: Many young animals are observed to be "playful," a behavior pattern usually associated with "practicing" or preparing for such adult activities as catching and killing of prey, or dominance contests. Animal play, while not having any apparent "purpose," is sometimes explained as exercise or an innate honing of physical dexterity, both of which can be seen as serving an individual's future survival potential. Purple Martins commonly engage in flight play with the green leaves they discard from their nest cups after they have dried up. Martins will fly out of their nest compartment with a dried leaf in their beak, then repeatedly drop and recatch it in flight. Often, other colony members will join in and play "catch" with the leaf before it finally hits the ground and the game ends.
Plumage: The collective term for all the feathers that cover a bird's body. The plumage of the male Purple Martin does not assume its familiar, purplish-black color until the bird is in its second potential breeding season.
Pneumatization of bone: The term means "filled with air." One of the adaptations permitting birds the lightness of weight necessary for flight, is their hollow bones. In contrast, mammals have solid bones. But, the hollow bones of birds are also filled with air sacs that are connected to the respiratory system.
Polygamous: Term to describe an animal species that pairs with or has more than one mate at a time. Most Red-winged Blackbirds are polygamous, with each male having a "harem" of females nesting within his territory. Compare with "Monogamous" and "Promiscuous."
Porch Domination: The tendency of dominant male Purple Martins to claim and defend adjacent nest cavities in a martin house, especially when they are connected by a common porch. Because of male porch domination, typically-designed martin houses rarely will exceed a 50-60% room occupancy rate.
Porch Dividers: Metal or wooden porch barriers that landlords or martin house manufacturers need to add to their porches to prevent nestling martins from walking between adjacent nesting cavities using a shared porch. See "Contiguous Porches."
Predator: An animal that kills and eats another. The Purple Martin is a predator on the insects its eats and feeds to its young, but it (or its eggs) are in turn, predated by hawks, owls, falcons, raccoons, snakes, crows, jays, magpies, gulls, wrens, English House Sparrows, European Starlings, and even humans.
Preen Gland: Synonymous with "oil gland." See "Oil Gland."
Preening: The action by which a bird cleans, manipulates, and arranges the individual feathers of its plumage using its bill. Purple Martins spend a great deal of time perched near their nest compartments or gourds engaged in prolonged preening sessions where the whole plumage is tended to, virtually feather by feather.
Premature Fledgling: A nestling bird that has left the nest (for whatever reason) at a stage in its growth before it can fly or feed itself. In the Purple Martin, premature fledglings are thought to result from nest compartments that become overheated or infested with parasites. But the deliberate, aggressive actions of sub-adult, bachelor martins may also be involved. See "Fallouts".
Prognosticator: The calculator wheel developed and marketed by the Purple Martin Conservation Association used to predict hatching and fledging dates, and to determine nestling ages and breeding success. As the name implies, it is a device for telling the future (i.e., prognosticate). It also has the root name Progne in it, as in Progne subis, the Latin name of the Purple Martin.
Promiscuous: The term used to describe animals that copulate with several different partners within a short time span. Although the pair bond in Purple Martins is monogamous, males are highly promiscuous and will copulate (often forcibly) with any fertile female they can. Recent evidence suggests that subadult female martins are also highly promiscuous, "wanting" their eggs to be fertilized by older, genetically superior males. Compare with "Polygamous" and "Monogamous."
Renest: The act of building another nest and laying a replacement clutch after the failure or loss of the first nest or its eggs. The Purple Martin will attempt to renest (often in the same nest) if its first clutch fails to hatch or is lost to predation. But, if a nesting attempt fails after the young have hatched, renesting is unlikely in the martin.
Scout-arrival Date: The date the first martins are observed back at the breeding site where they bred the previous summer.
Secondary-cavity Nester: A bird species that will only nest in pre-existing nest cavities (such as abandoned woodpecker holes) because it does not have the ability to excavate its own. The Purple Martin, along with many other of our native, secondary-cavity nesters, face stiff nest-site competition from the introduced European Starling and English House Sparrow, who are also secondary cavity nesters.
Sexual Dimorphism: The differences in size, structure, or appearance exhibited between the males and females of some species. The Purple Martin exhibits sexual dimorphism because males and females each possess different plumage colors and markings during the breeding season.
Sexual Maturity: The age at which an organism is physiologically capable of breeding and raising young. Purple Martins reach sexual maturity and begin breeding at 11-months of age.
Single Brooded: Term applied to birds that raise only one "family" in a breeding season. Purple Martins are a single-brooded species, although there are a few records of them successfully raising second broods, particularly in the southern U.S. where the breeding season is a month or two longer than it is in the north.
Site Fidelity: The behavior of certain animals whereby they return breeding season after breeding season to the same nest site. Banding studies show that Purple Martins exhibit strong site-fidelity with the same individuals returning year after year to breed in the same martin houses (or gourd clusters).
Sleep: One of the most widespread misconceptions about birds is that they sleep with their heads tucked under their wings. In fact, the commonest sleeping posture, especially among songbirds, is with the head turned and resting on the back, and the bill tucked under the feathers of the shoulder (i.e., the scapular feathers). During the breeding season, Purple Martins sleep in their martin houses and gourds at night. In late summer and during the rest of their annual life cycle, martins sleep out in the open, on the exposed branches of trees, or on the pipes of South American oil refineries.
Soaring: A type of flight that is sustained without the flapping of wings and is therefore aided by some form of air movement, such as thermals or updrafts. Purple Martins commonly engage in soaring flight as they forage extremely high in the air for flying insects. It is a very graceful behavior for martin landlords to watch.
SREH: "Starling Resistant Entrance Hole" Martins have used these entrances in all parts of their breeding range, at established sites and new sites. Starlings are a serious threat to martins, and will try to take over martin nests by killing adult martins, destroying eggs and nestlings; testing and perfecting these entrance holes could prove extremely beneficial to martins.
Subadult: The term for birds in an age class younger than that of the adults. In martins, due to inexperience, subadult breeders have significantly lower reproductive success. See "SY," "ASY," and "adult."
Summer Resident: A species that breeds in a given area but spends the winter elsewhere. The Purple Martin is only a summer resident within the North American continent because the entire population migrates to the South American tropics for the non-breeding portion of their annual life cycle.
Sun-bathing behavior: The peculiar posture that many birds assume on bright, sunny days, while spreading and fluffing their feathers for the purpose of exposing their plumage (or skin) to the light and/or heat of the sun. While sun-bathing, martins position their bodies perpendicularly to the sun, lean way over, roll their heads way to the side, erect their throat feathers, close their eyes, and appear to be in a deep, motionless trance.
Sunning: Another term for "sun-bathing." There are several theories as to why birds sun. One is that is causes the ectoparasites living in their plumage to become more active, making it easier for them to be eaten or removed. Second, that it releases vitamin D from the preen oil, which in turn is ingested by the birds while preening. Third, that the sun dries and fluffs the feathers, helping maintaining good insulation. Fourth, that birds may be able to increase their energy reserves by absorbing solar radiation through the skin. And fifth, that it just, plain feels good.
SY: Bird banding terminology for "Second-year." This is a bird in its second calendar year of life. An SY-M is a subadult male Purple Martin. Subadult martins are reproductively mature, but not all of them breed. Most SY female Purple Martins breed, but not all SY males do because there are more males than females in the population. The SY plumage of Purple Martins is distinct from their ASY plumage. See "ASY" and "adult," and "subadult".
Synanthropic: Literally "living with man." The term refers to birds that are adapted to living in close association with humans, or in human-modified habitats. For instance, the American Robin has benefited greatly by the creation of urban lawns, with their shortly-cropped grasses, making worm capture easier. In many respects, the Purple Martin is the quintessential synanthropic species. For one, it's the only bird species in eastern North America that today, is totally dependent on humans for supplying it with nesting sites. Secondly, since it has been managed by man longer than any other species in North America, it has developed a very close relationship with man - so much so that it rarely will nest in martin housing placed any farther from human housing than about 100 feet. And finally, it appears it may have benefited by man's clearing of the forests for agriculture, both within its North America breeding range and its South American wintering range.
Syrinx: The organ of voice production unique to birds; a bird's "voice box." In most birds it is located over the junction of the trachea and the fork of the bronchi. Purple Martins are able to produce the wide repertoire of beautiful vocalizations they do, mainly because they have a highly-developed syrinx.
Territory: An area of ground or airspace (including food sources and nest sites) that an organism defends against use by other members of its species. Because aggressive Purple Martins defend territories encompassing several adjacent nest compartments.
Transient: A species or population that migrates through a given area, but does not breed or winter there. Twice a year, during both its northward (spring) and southward (fall) migrations, the Purple Martin passes through Central America where it is present only as a transient.
Wintering Grounds: The geographic area that an animal migrates to after breeding in summer. The Purple Martin migrates to its South American wintering grounds for the non-breeding season, although it is southern hemisphere summer there.
Zero Paternity: Males who have been totally cuckolded by their mates a nd are totally unrelated, genetically, to the offspring hatched from the eggs in their nest, laid by the female to which they are paired. See "Complete Paternity" and "Partial Paternity."