キガシラアオハシインコ 対 チャタムアオハシインコ

The most reliable field separation between Yellow-crowned Parakeet and Chatham Islands Parakeet is geographic: Yellow-crowned is found on New Zealand's main islands and subantarctic Auckland Islands, while Chatham Islands Parakeet is restricted to the Chatham Islands. If seen outside the Chathams, it is Yellow-crowned. In appearance, both are bright green parakeets with a red forehead band and yellow forecrown, but Chatham Islands Parakeet's red band does not reach the eyes and it has green lores, while Yellow-crowned's red band is broader and fronts a more golden crown. Both show bluish or violet-blue in the wings in flight. Bill size is slightly larger in males of both species, but this is subtle. In the field, focus on location and the details of the red and yellow on the face for separation.

1. Location is decisive: If you are not on the Chatham Islands, you are seeing a Yellow-crowned Parakeet, not a Chatham Islands Parakeet. Chatham Islands Parakeet is strictly endemic to the Chatham group.
2. Red forehead band shape: On Chatham Islands Parakeet, the red band is narrower and does not reach the eyes, leaving the lores green. On Yellow-crowned Parakeet, the red band is broader and fronts the golden crown, often extending closer to the eyes.
3. Lores color: Chatham Islands Parakeet shows green lores (between bill and eye), which is a subtle but useful mark if seen well. Yellow-crowned Parakeet's lores are not specifically described as green, and the red band may approach the eye more closely.
4. Yellow/golden forecrown: Both species have a yellow or golden forecrown, but the shape and extent differ. On Chatham Islands Parakeet, the yellow is more confined to the forecrown, while on Yellow-crowned Parakeet, it may appear more extensive and golden.
5. Red on rump (Chatham only): Chatham Islands Parakeet has some red on the sides of the rump, which is absent or not described for Yellow-crowned Parakeet. This is a subtle mark, best seen in perched birds or in good light.
6. Wing coloration in flight: Both show bluish or violet-blue in the outer primaries and wing coverts when the wings are spread. This is not a separator between the two, but helps confirm the genus.
7. Bill size and shape: Males of both species have larger bills than females, but this is subtle and not a reliable field mark unless birds are side by side and sexed.
8. Sexual dimorphism: Females are slightly smaller and have smaller bills in both species, but this is not a strong field mark.
9. Size and structure: Both are medium-sized, long-tailed parakeets. Yellow-crowned Parakeet averages about 46 g; Chatham Islands Parakeet is similar but not precisely measured in the sources.
10. Habitat context: If you are in tall, unbroken forest on New Zealand's main islands, you are likely seeing Yellow-crowned Parakeet. Chatham Islands Parakeet is only on the Chatham Islands.
11. No age-specific wing pattern differences: There are no described differences in juvenile or immature wing pattern between these two species. Both should look similar in flight regardless of age.
12. No vocal differences described: The sources do not provide vocalization differences, so do not rely on call or song for separation.
13. Pitfalls: The greatest risk of confusion is in captivity or in photos without location data, as the facial pattern differences are subtle. In the field, always check location first, then the extent and placement of red and yellow on the face.
14. Hybridization context: Chatham Islands Parakeet is threatened by hybridization with other parakeets on the Chathams, but this is not a field separation issue with Yellow-crowned Parakeet, as their ranges do not overlap.
15. Summary tip: For field ID, always start with location, then check the red band shape and lores color. If the red band is narrow and the lores are green, and you are on the Chatham Islands, it is Chatham Islands Parakeet. If the red band is broader and fronts a golden crown, and you are on the main NZ islands, it is Yellow-crowned Parakeet.

Yellow-crowned Parakeet averages about 46 g in mass [wikidata], while no specific mass is given for Chatham Islands Parakeet, but both are described as medium-sized parakeets with long tails. Males are larger than females in both, with females having proportionally smaller bills. In the hand, Yellow-crowned males may appear a bit more robust, but this is not a reliable field mark at a distance.

Both species are bright green with a red band across the forehead and a yellow forecrown. For Chatham Islands Parakeet (all ages), the red band is narrower, does not reach the eyes, and the lores (the area between the bill and the eye) are green. There is also some red on the sides of the rump. The yellow on the forecrown is described as golden or yellow, similar to Yellow-crowned, but the distribution of red and yellow is subtly different. In Yellow-crowned Parakeet, the red band is broader and fronts a golden crown, and the lores are not specifically described as green. Both species show bluish or violet-blue in the outer primaries and wing coverts when in flight. No age-specific wing pattern differences (such as juvenile panels or trailing edges) are noted for either species in the available sources.

Yellow-crowned Parakeet prefers the upper canopy of tall, unbroken forest, often staying high in the trees, while Chatham Islands Parakeet's behavior is less specifically described but is likely similar as a forest-dwelling parakeet. Both species are likely to be seen foraging in trees and moving in small groups. There is no mention of distinctive flight style or jizz differences between the two.

Habitat is a strong separator: Yellow-crowned Parakeet is found across New Zealand's main islands (North, South, Stewart) and the Auckland Islands, favoring mixed podocarp and southern beech forests, and sometimes high-altitude meadows. Chatham Islands Parakeet is strictly endemic to the Chatham Islands group and is not found elsewhere. If you are not on the Chatham Islands, you are not seeing a Chatham Islands Parakeet.