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NPWRC - Biology Encyclopedia
Category: Animals and Nature > Glossary of avian terms
Date & country: 22/08/2008, US
Words: 236


Accuracy
the closeness of computations or estimates to the exact or true value (Marriott 1990:2).

After-hatching-year (AHY) bird
a bird in at least its second calendar year of life (Pyle et al. 1980:27; Canadian Wildlife Service and U.S. Fish and Wildlife Service 1990:5-47).

After-second-year (ASY) bird
a bird in at least its third calendar year of life (Pyle et al. 1980:27; Canadian Wildlife Service and U.S. Fish and Wildlife Service 1990:5-47).

After-third-year (ATY) bird
a bird in at least its fourth calendar year of life (Canadian Wildlife Service and U.S. Fish and Wildlife Service 1990:5-47).

Allopatric
occurring in different places; usually refers to geographical separation of populations (Ricklefs 1970:865). The populations may exhibit divergence in behavior, morphology, or genetic composition.

Annual
referring to an organism that completes its life cycle from birth or germination to death within a year (Ricklefs 1970:865).

Area-sensitive species
species that respond negatively to decreasing habitat patch size (Finch 1990:20).

Assemblage
a set of organisms whose pattern of organization (with respect to competition, predation, mutualism, etc.) is unknown (Giller and Gee 1980:537) (cf Community).

Assessment endpoint
see Endpoint.

Association
a group of species living in the same place at the same time (Ricklefs 1970:865).

Atlas
the result of a comprehensive survey of a large geographical area that maps the occurrence (or occurrence and relative abundance) of species in subdivisions of that area. An atlas is usually based on a grid of fixed intervals of distance or degrees latitude and longitude. It is restricted to a particular season of the year, usually the breeding season (Ralph 1980:577).

Biodiversity
(1) the variety of life forms, the ecological roles they perform, and the genetic diversity they contain (Wilcox 1980:640); (2) the variety from molecular, population, and interspecific levels up to the heterogeneity of ecosystems and landscapes (Hansen and diCastri 1990:5) (syn. biological diversity).

Biogeography
the study of the geographic distributions of organisms, both past and present (Brown and Gibson 1980:557).

Biological species concept
the idea that species are groups of natural populations that are reproductively isolated from other such groups (McKitrick and Zink 1980:2) (cf Phylogenetic species concept).

Biomarker
the variation, induced by a substance foreign to the body, in cellular or biochemical components or processes, structures, or functions that is measurable in a biological system or sample (McCarthy et al. 1990:2).

Boundary
the edge between different habitat types. If distinctive, a boundary can be considered a separate edge habitat or ecotone. Boundaries that are readily crossed by an organism are called permeable, those that are crossed reluctantly are called semipermeable, and those that are not crossed are called impermeable (Dunning et al. 1990:173).

Breeding Bird Atlas
see Atlas.

Breeding Bird Census (BBC)
a census program of the National Audubon Society in North America that uses the spot-mapping method during the breeding season (Ralph 1980:577).

Breeding Bird Survey (BBS)
a cooperative program of the U.S. Fish and Wildlife Service and the Canadian Wildlife Service for monitoring population changes in North American breeding birds by using point counts along roads (Ralph 1980:577).

Breeding dispersal
movement of individuals that have reproduced between successive breeding sites (Greenwood 1980:1141).

Brood parasitism (interspecific)
the laying of eggs by an individual of one species in nests of other species with subsequent care for the parasite young provided by the hosts (Lanyon 1990:77) (syn. breeding parasitism, nest parasitism [Thomson 1960:594]).

Capture-recapture method
a procedure involving the distinctive marking of individuals and their subsequent recapture (or sighting) to estimate population size and other population parameters (Ralph 1980:577) (syn. mark-recapture).

Carrying capacity
the maximum number of individuals that can use a given area of habitat without degrading the habitat and without causing social stresses that result in population reduction (McNeely et al. 1990:153).

Catastrophe
an event that causes sudden decreases of population size or the entire elimination of subpopulations (Ewens et al. 1980:62).

Census (noun)
a count of all individuals in a specified area over a specified time interval (Ralph 1980:577).

Census (verb)
the act or process of counting all individuals within a specified area and estimating density or a total population for that area (Ralph 1980:577).

Census efficiency
proportion of actual population density that is assessed by a census (Ralph 1980:577) (cf detectability).

Christmas Bird Count
an annual project, in the Americas, of the National Audubon Society involving a one-day count in December of the individuals of all species observed within a circle that is 15 miles (24 km) in diameter (Ralph 1980:577).

CITES species
species (675 as of this writing) listed under the 1975 Convention on International Trade in Endangered Species (CITES), which is administered by the United Nations Environment Programme. Such species cannot be commercially traded as live specimens or wildlife products because they are endangered or threatened with extinction (Miller 1990:422).

Climate change
changes in the global climate system in response to physical feedbacks, chemical feedbacks, and changes in terrestrial and aquatic systems caused by humans and nature (adapted from Lubchenco et al. 1991).

Climax
the endpoint of a successional sequence; a community that has reached a steady state under a particular set of environmental conditions (Ricklefs 1970:867).

Cline
a geographic gradient in a measurable character, or gradient in gene, genotype, or phenotype frequency (Endler 1970:180).

Coarse-grained
referring to qualities of the environment that occur in large patches with respect to the activity patterns of an organism. This results in the organism's ability to select usefully from among qualities (Ricklefs 1970:867) (cf Fine-grained).

Common Birds Census(UK)
a program of the British Trust for Ornithology for censusing breeding birds using the spot-mapping method (Ralph 1980:577).

Community
a group of organisms, generally of wide taxonomic affinities, occurring together. Many will interact within a framework of horizontal and vertical linkages such as competition, predation, and mutualism (Giller and Gee 1980:539) (cf Assemblage).

Competition
an interaction between members of two or more species that, as a consequence either of exploitation of a shared resource or of interference related to that resource, has a negative effect on fitness-related characteristics of at least one of the species (Wiens 1989b

Connectedness
the structural links between habitat patches in a landscape; can be described from mappable features (adapted from Baudry and Merriam 1980:23).

Connectivity
a parameter of landscape function that measures the processes by which a set of populations are interconnected into a metapopulation (adapted from Baudry and Merriam 1980:23).

Constant-effort mist netting
a capture method, standardized over space and time, used for counting numbers of birds captured in mist nets (Ralph et al. in press).

Contact
a single field record of an individual by sight or sound (Ralph 1980:577) (syn. detection, cue, registration, observation).

Corridor
a spatial linkage that facilitates movements of organisms among habitat patches in a landscape (adapted from Merriam 1980:16).

Count (noun)
(1) the act or process of enumerating; (2) the number or sum total obtained by counting (Ralph 1980:577).

Count (verb)
to record the number of individuals or groups present in a population or population sample (Ralph 1980:577) (cf Census, Index).

Deforestation
removal of trees from a forested area without adequate replanting or natural regeneration (Miller 1990:A6).

Demographic parameters
fecundity and mortality parameters used to predict population changes, such as number of eggs laid per clutch, the frequency at which clutches are laid, the survivorship of eggs and young in the nest and to the age at first reproduction, and the subsequent survival of the adults throughout their lifetime (Ricklefs 1970:367).

Density
the number of units (e.g., individuals, pairs, groups, nests) per unit area (Ralph 1980:577) (cf Frequency).

Density-dependent
having influence on individuals in a population in a manner that varies with the degree of crowding in the population (Ricklefs 1970:868).

Density-independent
having influence on individuals in a population in a manner that does not vary with the degree of crowding in the population (Ricklefs 1970:868).

Detectability
a measure of the conspicuousness of a species equal to the proportion of actual units (individuals, territorial males, etc.) observed on a given area (Ralph 1980:577).

Detection distance
the distance from the observer at which the individual or cluster of individuals is seen or heard (the radius in point counts and the lateral or perpendicular distance in transect counts) (Ralph 1980:577-578).

Direct competition
the exclusion of individuals from resources by aggressive behavior or use of toxins (Ricklefs 1970:868).

Dispersal
the movement of organisms away from the place of birth or from centers of population density (Ricklefs 1970:868) (see Breeding dispersal, Natal dispersal).

Dispersion
(1) the pattern of spacing of individuals in a population (Ricklefs 1970:868); (2) the nonaccidental movement of individuals into or out of an area or population, typically a movement over a relatively short distance and of a regular nature (Lincoln et al. 1980:70).

Disturbance
any relatively discrete event in time that disrupts ecosystem, community, or population structure and changes resources, substrate availability, or the physical environment (Turner 1980:181).

Ecocline
a geographical gradient of vegetation structure associated with one or more environmental variables (Ricklefs 1970:868).

Ecological effects characterization
the identification and quantification of the adverse effects elicited by a stressor and, to the extent possible, the evaluation of cause-and-effect relations (Risk Assessment Forum 1990:5).

Ecological risk assessment
a process that evaluates the likelihood that adverse ecological effects may occur or are occurring as a result of exposure to one or more stressors. Ecological risk assessment may evaluate one or many stressors and ecological components (Risk Assessment Forum 1990:2).

Ecological risk characterization
a process that uses the results of the exposure and ecological effects analyses to evaluate the likelihood of adverse ecological effects associated with exposure to a stressor (Risk Assessment Forum 1990:5).

Ecosystem
the totality of components of all kinds that make up a particular environment; the complex of biotic community and its abiotic, physical environment (McNeely et al. 1990:153).

Ecotone
a habitat created by the juxtaposition of distinctly different habitats; an edge habitat; a zone of transition between habitat types (Ricklefs 1970:869) or adjacent ecological systems having a set of characteristics uniquely defined by space and time scales and by the strength of the interactions (Hansen and diCastri 1990:6) (see Boundary).

Edge effect
(1) changes in a community due to the rapid creation of abrupt edges in large units of previously undisturbed habitat (Reese and Ratti 1980:127); (2) tendency for increased variety and density of organisms at community or habitat junctions (Odum 1970:157).

Edge species
species preferring the habitat created by the abutment of distinctive vegetation types (Ricklefs 1970:869).

Endangered Species Act
1973 Act of U.S. Congress, amended several times subsequently, that elevates the goal of conservation of listed species above virtually all other considerations. The act provides for identifying (listing) endangered and threatened species or distinct segments of species, monitoring candidate species, designating critical habitat, preparing recovery plans, consulting by federal agencies to ensure t...

Endemic
confined and native to a certain region (Ricklefs 1970:869).

Endpoint
a characteristic of an ecological component that may be affected by exposure to a stressor (Risk Assessment Forum 1990:12); a characteristic of valued environmental entities that are believed to be at risk (Suter 1990:9). Suter (1990) distinguished two types of endpoints

Environment
physical and biological surroundings of an organism, including the plants and animals with which it interacts (Ricklefs 1970:869).

Environmental characterization
the prediction or measurement of the spatial and temporal distribution of a stressor and its co-occurrence or contact with the ecological components of concern (Risk Assessment Forum 1990:5).

Environmental gradient
a continuum of conditions, such as the gradation from hot to cold environments (Ricklefs 1970:869).

Equitability
(1) evenness relative to any specific standard or model of species abundance (Peet 1970:288); (2) uniformity of abundance in an assemblage of species. Equitability is greatest when all species are equally numerous (Ricklefs 1970:869) (syn. evenness).

Estimator
a function of sample data that describes or approximates a parameter (Ralph 1980:578).

Evenness
the uniformity of abundance between species in a community (Peet 1970:288).

Exploitation
the removal of individuals or biomass from a population by predators or parasites (Ricklefs 1970:870).

Exploitation competition
competition in which two or more organisms consume the same limited resource (Ehrlich and Roughgarden 1980:620) (cf Interference competition).

Extinction
(1) the complete disappearance of a species from the earth (Miller 1990:A5); (2) the total disappearance of a species from an island (this does not preclude later recolonization) (MacArthur and Wilson 1960:187) (cf Extirpation, Local extinction).

Extirpation
the elimination of a species from an island, local area, or region.

Extractive reserves
conservation areas that permit certain kinds of resource harvesting on a (theoretically) sustainable basis (Soul‚ 1990:747).

Fecundity
rate at which an individual produces offspring, usually expressed only for females (Ricklefs 1970:870).

Feral
escaped from domestication (Long 1980:7). Feral individuals may be descendants of the original escapees.

Fine-grained
referring to qualities of the environment that occur in small patches with respect to the activity patterns of an organism. This results in the organism's inability to distinguish qualities usefully (Ricklefs 1970:870) (cf Coarse-grained).

First-year bird
a bird in its first 12-16 months (or until its second prebasic molt) (Pyle et al. 1980:27) (see Hatching-year bird, After-hatching-year bird).

Fitness
the average contribution of one allele (i.e., one form of a gene) or genotype to the next generation or to succeeding generations, compared with that of other alleles or genotypes (Futuyma 1970:503). It may be either an absolute value, measured by the number of progeny per parent, or it may be relative to some reference genotype (Crow and Kimura 1970:224).

Fixed-distance method
see Strip transect method, Point count method.

Fledging success
(1) the average number of offspring fledged (i.e, raised until they leave the nest) per female (May and Robinson 1985); (2) percentage of hatchlings that fledge (Robinson and Rotenberry 1990:280).

Floating birds
reserves of nonbreeding or nonterritorial birds, usually of undetermined age, present in breeding or territorial populations (von Haartman 1970:433-435).

Floristic
referring to studies of the species composition of plant associations (Ricklefs 1970:870).

Flyway
a broad-front band or pathway used in migration (Welty 1970:471).

Food chain
a feeding sequence, such as seed-to-songbird-to-raptor, used to describe the flow of energy and materials in an ecosystem (adapted from Ehrlich and Roughgarden 1980:620).

Food web
an abstract representation of the various paths of energy and material flow through populations in the community (Ricklefs 1970:870).

Forest fragmentation
patchwork conversion and development of forest sites (usually the most accessible or most productive ones) that leave the remaining forest in stands of varying sizes and degrees of isolation (Harris 1980:4).

Forest-interior species
species that tend to avoid edge habitats and that require large tracts of forest habitat for nesting and foraging (Whitcomb et al. 1980:139).

Fractal dimension
an index of the complexity of spatial patterns (Turner 1980:175).

Fractal geometry
a method to study shapes that are self-similar over many scales (Turner 1980:175).

Frequency
the number of plots, stations, counts (visits), or intervals in which a species is detected; when expressed as a fraction of the total sampled, it becomes relative frequency (Ralph 1980:578) (cf Density).

Functional response
the change in an individual predator's rate of exploitation of prey as a result of a change in prey density (Ricklefs 1970:870) (cf Numerical response).

Gap analysis
the process of identifying and classifying components of biodiversity to determine which components already occur on protected areas and, conversely, which are un- or underrepresented on protected areas (Scott et al. 1990).

Gap formation
the creation of a habitat patch of different characteristics within a larger patch (Wiens 1989b:201).

Gene flow
the exchange of genetic traits between populations by movement of individuals, gametes, or spores (Ricklefs 1970:870).

Generalist
a species with broad food preferences, habitat preferences, or both (Ricklefs 1970:871) (see Specialist).

Generation time
the average age at which a female produces her offspring, or the average time for a population to increase by a factor equal to the net reproductive rate (Ricklefs 1970:871).

Genetic drift
the change in allele frequency due to random variations in fecundity and mortality in a population (Ricklefs 1970:871).