FA-65787 / Ecological population dynamics / Member archive

Monthly population with seasonal breeding window: density-dependent births · case 02

Populations above the cap lose animals through negative births.

Member previewVariant 2 · 3 implementations · 7 checks per implementation

Case contract

Calendar month of step t is ((start_month-1+t) mod 12)+1; the breeding window is inclusive and may wrap across the new year (start > end); each month survival is applied first, then in breeding months births fecundity*N*max(0,1-N/cap); return monthly N rounded 4.

Why this case matters

Population projections set harvest quotas, conservation status and pest-control timing; a wrong update order, boundary or rate conversion silently changes management advice.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
regression: above cap no births	`[459.7312, 436.3139, 421.5999]`	`[495.0, 490.05, 485.1495]`	Failed

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