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abrupt: Generally refers to a call that starts at nearly maximum volume (e.g., Dickcissel). A call said to have an abrupt ending ends at nearly maximum volume. See "lazy".

arched: Refers to a call that descends then rises (or vice-versa) in pitch. We use the term to refer to how a call sounds and also to its shape in a spectrogram. For example, a Chipping Sparrow flight call is upward-arched, while a Gray-cheeked Thrush flight call is downward-arched:



      upward-arched Chipping Sparrow flight call                    downward-arched Gray-cheeked Thrush flight call


band: The time-frequency contour of a single tone in a spectrograph.


burry: Subtle modulations with an "r" sound (e.g., Veery).


buzzy: A "z"-sounding overtone created by modulations (e.g., Yellow Warbler) or very closely-spaced separate notes creating a similar effect (e.g., Dickcissel). A finer buzz has faster modulations (e.g., Swamp Sparrow) and a coarser buzz has slower modulations (e.g., Indigo Bunting).


chip note: A short vocalization, often used as an alarm note, given primarily by perched birds year-round. In many species this call can be phonetically rendered as "chip".


coarse: Generally used to characterize the buzzy quality of a call. A call with a coarser buzz has slower modulations (e.g., Louisiana Waterthrush has a coarser buzz than Worm-eating Warbler).


contact call: A short call used primarily for the purpose of birds staying in contact with one another. Sometimes referred to as the location call. Serves as the flight call in many species.


crepuscular: Refers to the behavior of increased activity in the period of twilight around dawn and dusk.


dawn: The period between first light and sunrise.


descending: Lower in pitch toward the end of the call (e.g., Northern Parula).


diurnal migration: Migration taking place during the day.


"double-banded up-seep" group: A group of warblers with very similar-sounding "seep" calls including Orange-crowned, Nashville, Tennessee, Golden-cheeked, and Black-throated Green. Spectrograms of these five species all show a distinct double band that is usually rising in pitch. All are extremely similar and probably not reliably distinguishable by flight call although average differences exist. See short rising seeps


dry: Lacking a musical or liquid sound. Opposite of sweet. Used as a comparative term, for example, Orange-crowned Warbler gives a drier flight call than American Redstart.


duration: Length of the call. Most flight calls are less than half a second in duration. Most warbler flight calls are about one tenth of a second in duration.


dusk: Period between sunset and last light.


emphatic: Forceful. Generally refers to longer calls that begin abruptly (e.g., Northern Flicker's "skeew" call).


fine: Generally refers to the buzziness of a call. A call with a finer buzz has faster modulations. For example, Chestnut-sided Warbler has finer modulations than Louisiana Waterthrush.


flight call: The primary vocalization given in long, sustained flights such as during migration. For most species, this same call is also used in a variety of other circumstances, including by perched birds. In most cases, this is the same as the contact call or location call.


forced migration: Migration during which nocturnal migrants are forced to continue migrating during the day (or diurnal migrants to continue at night) due to being caught over water or other areas of unsuitable habitat, or due to limited space or food resources in a given area. At times, this behavior may overlap with "redetermined migration".


frequency: The number of sound waves per unit of time. For example, Grasshopper Sparrow flight call has a frequency of about 8000 sound waves per second, which is the same as 8 kHz.


harmonic: A tone in a series of overtones in which each tone has a frequency that is an integral multiple of the same basic frequency.


harmony: A simultaneous combination of sounds. Many species of birds, for example Savannah Sparrow, produce two simultaneous sounds with their syrinx, creating harmony. To the human ear, this harmony may give the call a sibilant or tinny quality.


husky: Refers to a harsh or dry characteristic in a bird call (e.g., Ruby-crowned Kinglet).


lazy: Generally refers to a call that starts softly and builds to a higher volume toward the middle or end (e.g., Magnolia Warbler). See "abrupt".


lisping: Refers to a soft "th" sound in a bird call (e.g., Song Sparrow).


location call: See "contact call".


mellow: A soft, gentle, relaxed sound, often low-pitched and pure-toned (e.g., Eastern Bluebird).


mewing: A soft, somewhat complex sound, usually descending in pitch (e.g., Blue-gray Gnatcatcher).


migration flight: Flight to or from wintering or breeding grounds. See the following types of migration: "diurnal" and "nocturnal migration", "redetermined migration", "forced migration", "resumed migration", "onward migration".


modulation: The transition from one pitch to another. The characteristic that gives a call a buzzy sound. On a spectrogram, modulations are the sequence of "humps". A call with faster modulations means the pitch variations occur over a shorter period of time (i.e., greater frequency).


modulation peak: The part of a modulated call when the frequency rises and then falls, sometimes called a modulation "hump". The shape of the modulation peak is sometimes a useful criterion for distinguishing zeep calls.


modulation trough: The U-shaped or V-shaped area between modulation peaks. The shape of the modulation trough is sometimes a useful criterion for distinguishing zeep calls.


monotone: All on one pitch. We use this as a comparative term. For example, Cedar Waxwing's “seeeee” call is more monotone than Red-winged Blackbird's "seee" call:



 "Seeeee" call from Cedar Waxwing                 "Seee" call from Red-winged Blackbird


morning flight: Any morning movement by nocturnal migrants. In our species accounts, we seldom use the term morning flight but typically split the term into three more specific categories of flight behavior (see "onward migration", "redetermined migration", and "resumed migration").


nasal: A descriptive term used for certain bird vocalizations that sound as though they were made when speaking partly through the nose (e.g., Red-breasted Nuthatch calls).


nocturnal migration: Migration taking place at night.


onward migration: Migration by primarily nocturnal migrants that takes place through the night and into the day without stopping. This behavior is seen in spring in the Gulf coast region and in fall on Atlantic pelagic trips. It is also at high latitudes where there is perpetual daylight. See "morning flight".


piercing: A sound that hits the ear more clearly than other sounds of equal volume (e.g., Cape May Warbler).


pitch: The subjective measure of how high or low a flight call sounds based on a combination of frequency and the distribution of loudness within the call. Used especially for describing complex sounds made up of different frequency components or having a broad frequency range (e.g., Lapland Longspur rattle calls sound higher-pitched than McCown's Longspur rattles even though McCown's typically have higher frequency components. See Longspur rattles).


plaintive: A soft, mournful sound, usually off-key (e.g., Rose-breasted Grosbeak).


pure-toned: Refers to a call that lacks audible modulations, thus with a clear, simple sound (e.g., Yellow-throated Warbler).


raspy: A harsh, grating, or ripping sound (e.g., Gray-cheeked Thrush).


redetermined migration: Early morning (usually about 1-4 hours) and sometimes early evening movement by many species of nocturnal migrants in a direction different from (sometimes opposite from) that of the nocturnal flight. This behavior is most obvious in coastal areas but also occurs inland and offshore (Baird & Nisbet 1960; Gauthreaux 1978; Hall & Bell 1981). The function of this behavior is not fully known but likely serves to compensate for lateral drift incurred during the previous night's migration (Lack & Williamson 1959; Baird & Nisbet 1960; Gauthreaux 1978; Moore 1990) and may also be related to the selection of stopover habitat (Wiedner et al. 1992). Flight direction at a given location may be strongly influenced by local geography and wind direction (Baird & Nisbet 1960). See "morning flight".


resumed migration: Limited diurnal migration, mostly in the morning (but sometimes well into the day), by primarily nocturnal migrants, typically continuing in the same direction as the nocturnal flight. This involves birds that stop briefly at dawn before continuing. Unlike "redetermined migration", this behavior is commonly seen in interior North America as well as coastal areas. Dickcissel and Bobolink are good examples of species that exhibit this behavior. See "morning flight".


ringing: A clear, loud, resonant sound (e.g., Bobolink).


rising: Higher in frequency toward the end of the call (e.g., Eastern Meadowlark).


seep: A generic term for any of a variety of short, relatively pure-toned flight calls.


sharp: A clear, abrupt, somewhat piercing sound.


shrill: High-pitched and piercing in quality (e.g., Pine Grosbeak).


sibilant: A hissing "s", "sh", or soft "z"-sounding overtone (e.g., Le Conte's Sparrow). Often caused by the harmony between two tones close in pitch. See harmony.


slurred: Two or more sounds blended together without clear annunciation (e.g., Chestnut-collared Longspur).


soft: Low in volume or loudness.


squeaky: A piercing, high-pitched, slightly sweet overtone (e.g., Lark Sparrow).


strident: A high-pitched sound with a subtle raspy quality (e.g., Pine Siskin).


sweet: A subtle musical or liquid overtone. Opposite of dry. For examples, Blackburnian Warbler gives a subtly sweeter flight call than Worm-eating Warbler.


trill: A series of separate notes spaced closely together (e.g., Cedar Waxwing) or widely-spaced modulations creating a similar effect (e.g., Henslow's Sparrow).


vegetation reflection: Refers to a characteristic of an audio spectrogram that is the result of a reflection of a bird call off nearby vegetation.


vibrant: Refers to a sound with a mechanical vibrating overtone.


zeep group: A group of warblers with very similar-sounding, short, buzzy calls including Yellow, Magnolia, Blackburnian, Bay-breasted, Blackpoll, Cerulean, Worm-eating, Kentucky, and Connecticut Warblers, and Northern and Louisiana Waterthrushes.