Abbreviation Key

CHR

Captive hybridization reported. Hybrids reported in captivity.

NHR

Natural hybridization reported. Hybridization has been reported to occur under natural circumstances. When a cross is classified as NHR, it either occurs rarely or has been reported rarely, perhaps due to a lack of study. Since these two cases are often hard to distinguish, an NHR classification is best interpreted as indicating a general lack of specific information concerning the frequency with which a cross occurs.

ONHR

Ongoing natural hybridization reported. “Ongoing” indicates either that 1) multiple reports exist of the cross occurring in a natural setting or that 2) at least one report indicates that natural hybrids occur on an ongoing basis (at relatively low levels).

ENHR

Extensive natural hybridization reported. “Extensive” indicates either that 1) many reports exist of the cross occurring in a natural setting or that 2) at least one report indicates that many natural hybrids occur on an ongoing basis.

CANHR

Captive and natural hybridization reported. Hybridization has been reported to occur both in captivity and in a state of nature.

CAONHR

Captive and ongoing natural hybridization reported. See note under ONHR.

CAENHR

Captive and extensive natural hybridization reported. See note under ENHR.

NHI

Natural Hybridization Inferred

ENHI

Extensive natural hybridization inferred. Here “extensive” refers to the existence of a putative hybrid population.

CAENHI

Captive and extensive natural hybridization inferred. Here “extensive” refers to the existence of a putative hybrid population.

PHP

Putative hybrid product.

GMI

Geographically and morphologically and intermediate.

HPF

Hybrids are partially fertile (i.e., known to have had offspring).

HPF(vh)

Hybrids are inferred to be partially fertile due to the existence of variable hybrids.

♂/♂♂

male/males

♀/♀♀

female/females

HPF(♀♀)

Female hybrids are partially fertile (i.e., known to have had offspring).

HPF(♂&♀)

Hybrids are partially fertile in both sexes (i.e., both have had offspring).

HPF(+)

Available data suggests the hybrids are exceptionally fertile.

LFH

Low fertility in hybrids - available data suggests the hybrids in question are incapable of producing offspring or that they very rarely do so.

LFH(-)

Very low fertility in hybrids - Available data strongly indicates the hybrids in question are incapable of producing offspring.

LVH

Low viability in hybrids. Hybrids are less viable than the parental types.

BRO

Breeding range overlap.

DRS

Disjunct ranges. The breeding ranges of hybridizing pair do not overlap.

#

Specimen number

sp.

Unknown member (e.g., Crax sp. = “an unknown member of genus Crax”)

ACZ

Altitudinal contact zone.

↔

Cross is reversible.

F₁

First filial generation. An “F₁ hybrid” is one produced by an initial cross between two types (as opposed to one produced in later generations).

^†

Citations marked with this symbol contain illustrations of the hybrid.

~

Approximately

?/??

Indicates doubt/marked doubt