Domain: Natural Science — Ecology & Evolutionary Biology
Target concept: Courtship behavior of the European Robin: both sexes share the same orange-red breast (visually monomorphic), so courtship is signaled by behavior — males orient and present the breast while perched, and females respond with wing-quivering.

Video generation prompt: A male robin perches on a branch, engaged in a courtship interaction with a female robin perched on an adjacent branch. Fixed camera position, natural outdoor lighting, continuous unedited recording, no narration or text overlay.

Evaluation guide:
(i) Target concept: Sex-specific courtship BEHAVIOR in the European Robin (Erithacus rubecula). Note: both sexes of this species carry the same orange-red breast plumage (they are visually monomorphic), so the courtship exchange is distinguished by behavior, not color: the male stays perched and orients/presents his breast toward the female (no hovering display is required or expected; European Robin courtship display is perch-based); the female, also perched, responds with a bout of wing-quivering, a receptive/solicitation display related to courtship-feeding behavior in this species.
Minimum mechanism: the male's breast-presentation requires an unobstructed, camera-facing or oblique orientation and enough ambient light for the orange-red breast to register; the female's wing-quiver requires a stable perch and an unobstructed view of both wings; because the species is monomorphic, no color difference between the two birds should be scored as a criterion; only their perched positions, orientation, and distinct behaviors identify which bird is male and which is female.
(ii) Storyline: [Phase 1] Male perches stably on a branch, oriented toward the female → [Phase 2] Male presents his orange-red breast (frontal or oblique view, unoccluded), remaining perched throughout → [Phase 3] Female, perched on an adjacent branch, responds with a bout of bilateral wing-quivering → [Phase 4] Both birds maintain their perched positions and behavior for a sustained interval → Perspective constraint: fixed camera keeps both birds' full bodies visible, the male's breast oriented toward the camera-facing side, and wing-quivering fully visible in-plane; any foliage occlusion must be brief and natural only.

Manual:
Experimental Procedure
1. Place a live male European robin on a natural branch in partial shade; place a live female European robin on an adjacent branch within the same line of sight.
2. Position a fixed camera at eye level, 2–3 m distance, capturing both birds in frame under natural daylight.
3. Record continuously for 10 seconds with no intervention.
Observation of Experimental Phenomena
- The male robin remains perched throughout and orients his body to present his orange-red breast toward the female.
- The female robin remains perched throughout and performs a bout of bilateral wing-quivering, a receptive/solicitation display associated with courtship feeding in this species.
- Both birds maintain adjacent spatial relationship; no flight, hovering, aggression, or disengagement is observed.
Summary of Experimental Principles
European robins (Erithacus rubecula) are sexually monomorphic in plumage — both sexes carry the same orange-red breast — so sex-specific courtship roles are conveyed through behavior rather than coloration: the male perches and orients/presents his breast as a courtship display, while the female signals receptivity by wing-quivering while perched. Both behaviors are innate, sex-specific, and occur in close proximity under natural lighting; no hovering display is part of this mechanism.

Prompt Grounding rubric:
level_1: No male robin or no female robin present; or both birds absent; or presence of non-robin species; or camera not fixed (e.g., panning, zooming, handheld jitter visible); or lighting not natural (e.g., studio lights, strong artificial color cast, overexposed highlights or pitch-black shadows inconsistent with daylight); or no perching behavior visible in either bird.
level_2: Exactly one robin present (male or female only); or both robins present but not in adjacent positions (e.g., separated by >2x body length, occluded, or in different scenes); or camera viewpoint shifts (e.g., cut, reframe, perspective jump) during recording; or lighting shows clear artificial source indicators (e.g., single-direction harsh shadow with no ambient fill, unnatural rim light, chromatic spotlight).
level_3: Male robin and female robin both present, perched, and adjacent (side-by-side or on nearby branches within same frame); camera remains fixed (no pan/tilt/zoom/translation); lighting appears consistent with natural daylight (diffuse illumination, soft shadows, no specular glare inconsistent with outdoor conditions); no narration or text overlay.
level_4: All 3-point conditions satisfied AND male robin is positioned on a branch (not ground, air, or nest), female robin is also perched on a branch (not flying, hovering, or grounded), both birds face each other or share mutual orientation within the frame, and no visual artifact breaks continuity (e.g., no sudden brightness shift, no object flicker, no temporal discontinuity such as freeze or skip).
level_5: All 4-point conditions satisfied AND male robin displays red breast fully visible (frontal or oblique frontal view showing unoccluded red chest plumage), female robin exhibits visible wing vibration (both wings visibly oscillating in synchrony at same frequency, no static wings), both actions occur continuously and concurrently for ≥70% of video duration, and entire scene remains fully within natural outdoor context (e.g., leafy background, sky gradient, no studio backdrop or CGI artifacts).

Scientific and Causal Correctness rubric:
level_1: Male robin lacks a visible red breast (e.g., brown/gray chest, black chest, or red absent entirely) while perched; or female robin shows no wing vibration (wings fully still or asymmetrically flapping) while perched; or the sex-specific behaviors are swapped (e.g., male vibrates his wings instead of presenting his breast, or female presents/orients her breast instead of wing-vibrating); or either bird is shown hovering rather than perched during its display.
level_2: Red breast is present on the male but occluded for >50% of duration (e.g., turned away, blocked by foliage, silhouette against sky); or wing vibration occurs on the female but is intermittent (<3 full cycles) or asynchronous (left/right wings moving at different frequencies or amplitudes); or the male displays his breast while perched but the female is not present; or the female vibrates her wings while the male is not present.
level_3: Male robin has his red breast visible for ≥50% of duration while perched; female robin vibrates both wings synchronously for ≥50% of duration while perched; both birds are present and adjacent; the sex-specific behaviors are not reversed (male presents/orients his breast, female wing-vibrates); neither bird is shown hovering.
level_4: All 3-point conditions satisfied AND the male's breast is fully unoccluded and facing forward or obliquely forward (not profile-only or rear view) for ≥70% of duration; wing vibration is continuous, bilateral, and rhythmically regular (no pauses >0.5s between cycles, no unilateral movement); spatial adjacency is maintained throughout without separation or repositioning that breaks courtship context; both birds remain perched throughout (no hovering by either bird).
level_5: All 4-point conditions satisfied AND the male's breast color matches the natural European robin hue (distinctive warm orange-red, not blue, green, or otherwise off for this species); wing vibration amplitude is moderate and biologically plausible (wings remain near body plane, no exaggerated flapping or full extension like flight); no behavioral contradiction (e.g., male fleeing, female pecking male, aggressive postures); the female's wing-vibration occurs together with or shortly after the male's perched breast-presentation, consistent with a receptive response to the male's display.

Spatiotemporal Consistency rubric:
level_1: Robins teleport (appear/disappear without motion path); or abrupt lighting change (e.g., daylight to night in one frame); or structural break (e.g., branch vanishes/reappears, robin body parts disintegrate/reassemble); or severe motion stutter (≥3 frames frozen or duplicated consecutively); or extreme warping/distortion (e.g., fisheye stretch, melting edges).
level_2: Minor teleportation (e.g., robin shifts position >1 body length without visible motion trajectory); or flickering occluder (e.g., leaf blinking in/out inconsistently); or inconsistent shadow direction across frames; or mild warping (e.g., slight bulge at frame edge, minor perspective wobble); or inter-frame motion jerk (≥2 abrupt velocity changes per second).
level_3: No teleportation; no structural breaks; no abrupt lighting shifts; no visible warping or distortion; motion is continuous (no freezes, skips, or repeated frames); shadows remain directionally consistent; occlusion events (e.g., by leaves) follow natural entry/exit paths and maintain object persistence.
level_4: All 3-point conditions satisfied AND camera remains geometrically stable (no detectable parallax shift, no lens breathing, no focus breathing); branch and background elements retain consistent scale and perspective; robin motion trajectories are smooth (no robotic stepping, no velocity spikes); lighting remains uniform (no pulsing, no chromatic drift).
level_5: All 4-point conditions satisfied AND no visible micro-artifacts: no visible flicker along either bird's outline or feather edges, no visible noise bursts, no depth inconsistency (e.g., the robin in front of the branch is never rendered behind it mid-motion), and no visible strobing or brightness pulsing under steady viewing.