Urban Bioblitz 2D: Species Accumulation Curve

Bioblitz Setup

Volunteer surveyors 4

True species pool 55

Rarity skew (abundance) 1.30

Habitat patchiness 0.40

Live Survey Stats

Species observed

Effort so far

0.0 h

Est. total richness (Chao1)

0.0

Sampling completeness

effort (observer-hours) →richness ↑

How it works

Each survey volunteer wanders the park; any un-recorded individual within detection range becomes a confirmed record. Plotting cumulative species richness S(effort) against accumulated observer-hours gives the classic species accumulation curve — steep at first, then saturating as only rare, hard-to-find species remain:

S(t): number of distinct species recorded
      after t observer-hours of search effort.
      dS/dt shrinks as common species run out
      and only rare ones remain undetected.

Because the true richness is unknown while sampling is still incomplete, ecologists extrapolate it with a non-parametric estimator built from how many species were seen only once or twice — singletons (f₁) and doubletons (f₂). This simulator uses the bias-corrected Chao1 estimator:

S_Chao1 = S_obs + f1·(f1 − 1) / (2·(f2 + 1))

S_obs = species recorded so far
f1    = species recorded exactly once
f2    = species recorded exactly twice

Volunteer surveyors — more walkers accumulate observer-hours faster and cover more ground in parallel.
True species pool — the hidden total richness actually present in the park (unknown to the surveyors, revealed only through discovery).
Rarity skew — how uneven species abundances are; a high skew means a few common species and many rare ones, which flattens the accumulation curve and widens the gap between S_obs and Chao1.
Habitat patchiness — clusters species into a few dense patches instead of spreading them evenly, so surveyors miss patches entirely and richness estimates stay noisier for longer.

Undiscovered individuals render as dim grey dots; once a surveyor passes close enough, that individual is "recorded" and lights up in its species' own colour — exactly the moment a real bioblitz sighting gets logged. Drag the park view to pan and scroll or pinch to zoom in on any patch.

Undiscovered individual Confirmed species record Volunteer surveyor

drag to pan · scroll to zoom