Red-footed Falcon vs Eurasian Hobby

In short

The most reliable field mark between Red-footed Falcon and Eurasian Hobby is the underwing and body plumage: adult male Red-footed Falcons show uniform blue-grey underwings and body with red legs and vent, while adult Eurasian Hobbies have contrasting dark underwings and bold streaking on the underparts, with rufous 'trousers' and vent. Juveniles of both can be confusing, but the Hobby's streaked, rufous thighs and undertail coverts stand out. Structure also helps: Hobbies are bulkier and appear more swift-like in flight, with longer, more pointed wings and a squarer tail. Both species can be seen hunting in open country, but their flight style and plumage details are the best clues.

Identification tips

1. Juvenile/immature separation: Juvenile Eurasian Hobbies have rufous, streaked thighs and undertail coverts, and a generally browner, more scaled look above. Juvenile Red-footed Falcons are brown above, buff below with dark streaks, and have a face pattern like the adult female (white with dark eye-stripe and moustache), but lack the Hobby's rufous 'trousers.'
2. Adult male Red-footed Falcon: Uniform blue-grey above and below, with red undertail and legs. Underwings are plain grey. No streaking or rufous thighs.
3. Adult female Red-footed Falcon: Grey back and wings, orange head and underparts, white face with black eye-stripe and moustache. No bold underpart streaking or rufous thighs.
4. Adult Eurasian Hobby: Slate-grey above, dark crown, two short black moustache stripes, white throat, heavily streaked underparts, and rufous thighs and vent. Underwing is dark and patterned. Sexes are similar.
5. Underwing pattern: In flight, Hobby shows darker, more patterned underwings; Red-footed Falcon (especially adult male) has uniform grey underwings.
6. Face pattern: Hobbies have a dark crown and two short black moustache stripes, with a white throat. Red-footed Falcon females and juveniles have a white face with a single dark eye-stripe and moustache, but the overall effect is paler and less hooded than Hobby.
7. Flight shape: Hobby is longer-winged, more pointed, and swift-like, with a squarer tail. Red-footed Falcon is more compact, with shorter wings and a rounder tail.
8. Perched jizz: Hobbies look bulkier and longer-winged when perched; Red-footed Falcons are daintier and more upright.
9. Leg and vent color: Both species can show reddish legs and vent, but in Hobby the rufous 'trousers' are always present and more extensive, especially in adults and juveniles.
10. Underpart streaking: Hobby always shows bold black streaks on the underparts (except throat and vent), while Red-footed Falcon is plain or only lightly marked below (female/juvenile).
11. Sex differences: Only Red-footed Falcon shows strong sexual dimorphism (male blue-grey, female orange/grey/white); Hobby sexes are similar.
12. Habitat/context: Red-footed Falcon is more likely in steppe/grassland with colonies or nest boxes; Hobby in open country with scattered woods, marshes, or farmland.
13. Behavior: Hobby is more likely to be seen hawking insects or birds in fast, acrobatic flight, sometimes eating prey on the wing. Red-footed Falcon may hunt from perches or in more direct flight.
14. Size: Hobby is heavier and slightly larger, but overlap is considerable; use structure and plumage first.
15. Pitfalls: Juvenile Red-footed Falcon can be confused with Hobby, especially at a distance; focus on the presence or absence of rufous, streaked thighs and underwing pattern for best separation.

Size

Eurasian Hobby is noticeably heavier and slightly larger: average mass 211 g vs 158.5 g for Red-footed Falcon [wikidata]. Hobbies measure 29–36 cm in length (wingspan 74–84 cm), while Red-footed Falcons are 28–34 cm (wingspan 65–75 cm) [wikipedia]. In the field, Hobbies look longer-winged and more powerful, while Red-footed Falcons are daintier and more compact.

Plumage

Juvenile and immature birds are most often confused. Juvenile Red-footed Falcons are brown above and buff below with dark streaks, and their face pattern resembles the female: white with a dark eye-stripe and moustache. Juvenile Eurasian Hobbies are browner overall, with scaled upperparts and distinctive streaked, rufous thighs and undertail coverts. In flight, the Hobby's underwing is darker and more patterned, while Red-footed Falcon juveniles have less contrast.

Adult male Red-footed Falcons are all blue-grey with a red vent and legs, and uniform grey underwings. Adult female Red-footed Falcons have a grey back and wings, orange head and underparts, and a white face with black markings. Adult Hobbies of both sexes are slate-grey above, with a dark crown, two short black moustache stripes, white throat, heavily streaked underparts, and rufous thighs and vent. The Hobby's underwing is darker and more patterned than the Red-footed Falcon's. Sexes are similar in Hobby, but female Red-footed Falcons are much paler and more orange than males.

Behaviour

Both species hunt in open country, but the Hobby is more swift-like and acrobatic, often catching insects and birds on the wing, sometimes eating prey in flight. Hobbies are fast, powerful, and often seen gliding with sickle-shaped wings, resembling a giant swift. Red-footed Falcons are agile but less swift-like, and may be seen perching more often, especially near colonies or nest sites. Hobbies may hunt at dawn and dusk (crepuscular) when not breeding, while Red-footed Falcons are more diurnal.

Habitat

Both species prefer open country, but Red-footed Falcons are more closely tied to steppe, grasslands, and areas with scattered trees, often breeding in colonies (sometimes using nest boxes). Hobbies are more widespread in lowlands with scattered small woods, farmland, marshes, and even taiga and savannah. In Europe, Red-footed Falcons are more localized and declining, while Hobbies are widespread.