Most wildlife observation databases record when a person looked, not when an animal moved. iNaturalist contributors are diurnal creatures — they photograph what crosses their path during daylight hours, and the data reflects that. Before reading any of the charts below as evidence of animal behavior, hold that caveat firmly in mind.
With that said, the 390 timestamped records from the Saladita lagoon — all GBIF-grade iNaturalist submissions for three reptile species — do carry enough signal to ask whether American crocodiles, green iguanas, and black spiny-tailed iguanas are reported at different times of day. The Rayleigh test lets us measure how tightly those reports cluster on the 24-hour clock. Strong clustering (R near 1, p near 0) tells us observers reliably encountered these animals in specific windows. Weak clustering (R near 0) tells us encounters were spread across the day — which could mean broad activity, or simply random observer timing.
No time-of-day data exists in this dataset for birds, insects, mushrooms, plants, whales, or sea turtles. Those taxa come from date-only GBIF records. The diel section is therefore restricted to lagoon reptiles.
Observer-Bias Warning
All records are human-observed daytime submissions. The virtual absence of records before 06:00 and after 20:00 reflects observer behavior, not animal activity. Crocodylus acutus is crepuscular to nocturnal in its feeding behavior; this dataset cannot confirm or deny that. The peak hours below describe when visitors most often photograph these animals, which correlates with high human-activity windows, not necessarily peak animal activity.
What the data actually contains
Only the lagoon taxon group carries timestamps. Birds (placeholder dataset, n=0), insects, mushrooms, plants, whales, and turtles all arrived from GBIF as date-only records. The lagoon data comes from iNaturalist research-grade submissions where observers' phones logged GPS time at the moment of upload.
Species by hour-of-day
Rayleigh test results
| Species | n (timed) | Peak hour | R | p | Mode |
|---|---|---|---|---|---|
| Iguana iguana Green iguana |
176 | 12:40 pm | 0.6732 | < 0.001 * | Diurnal |
| Ctenosaura pectinata Black spiny-tailed iguana |
76 | 12:59 pm | 0.6212 | < 0.001 * | Diurnal |
| Crocodylus acutus American crocodile |
138 | 12:34 pm | 0.5573 | < 0.001 * | Diurnal |
* p < 0.05 — statistically non-uniform distribution on the 24-hour clock. See observer-bias warning above before interpreting as true diel signal.
When to look — practical guidance
How this was computed
Records were parsed from all _*_climatology.js artifacts in the site's API layer. Only records whose event_date field contained an ISO 8601 timestamp (HH:MM) were included in the diel analysis. Hour-of-day was extracted and accumulated into a 24-bin histogram per species and per taxon group.
Circular statistics were computed using the Rayleigh test for uniformity. Each hour h is converted to an angle θ = 2πh/24 radians. The mean resultant length R = √(C²+S²)/n measures how tightly the observations cluster around a single direction on the clock face (0 = perfectly uniform, 1 = all observations at the same hour). The Rayleigh z statistic z = nR² is tested against the null of circular uniformity using the approximation of Zar (1999).
Diel mode classification: peak hour 05–08 = crepuscular-dawn, 08–17 = diurnal, 17–21 = crepuscular-dusk, >21 or <05 = nocturnal. If R < 0.20 the distribution is classified as cathemeral regardless of peak hour.
All times are local device time as reported by iNaturalist submitters. No timezone correction was applied; Guerrero (UTC-6) observers submitting during daylight hours introduce at most a ±1 h ambiguity relative to solar time.