Each nesting pair claims the ground it can afford to defend. A bigger territory holds more prey but costs more to patrol and border. Watch borders settle, neighbours expand when a pair disappears, and prey stocks drop where eagles hunt.
Each experiment runs a fresh copy of the model with the current sliders (seeded, repeatable).
The science
Economic defendability (Brown 1964): a territory is worth holding while the marginal energy gained exceeds the marginal cost of defending it. Here a pair with territory area A, prey stock N and perimeter P has the daily budget
S = e I(N) - a sqrt(A) - b k (P_free + f P_shared) - 2 DEE, with intake I = Imax N / (N + Nh) (a Holling type II saturation).
e = 3 MJ per prey item, Imax = 6 items/day, Nh = 250 items, a = 0.25 MJ/day/km^0.5 (travel), b = 0.06 MJ/day/km (border patrol), k = intruder pressure (slider), f = 0.25 (neighbours already established fight less: the "dear enemy" effect). DEE is the daily energy expenditure of one adult; the default 3.2 MJ/day comes from the allometric field-metabolic-rate fit for birds, FMR = 10.5 M^0.681 kJ/day with M in grams (Nagy), for a 4.5 kg eagle. All other constants are illustrative, tuned for plausible territories of 30 to 150 km^2, not measured.
Borders: a cell belongs to the pair that is closest in distance divided by dominance weight (multiplicatively weighted Voronoi), but only inside that pair's radius. Each pair nudges its radius uphill on its own surplus (finite-difference gradient on the real map). Staircase perimeter on a grid overstates a smooth edge by 4/pi, so it is multiplied by pi/4.
Prey: per-cell logistic growth dP/dt = r P (1 - P/K) - (I/N) P in the owning territory, so heavy hunting pulls local density down. K follows habitat quality (meadows high, forest and alpine low). The renewal rate r is an effective value including immigration, not a pure birth rate. Pair condition rises or falls with the surplus; at zero the pair abandons the site and floaters may re-settle it.
Flight: in a coordinated turn tan(phi) = v^2 / (g R). The readout uses the visual patrol radius of the animated eagle with the chosen real speed; the drawn roll is exaggerated.
Simplifications: one prey type, no seasons, no individual hunting, circular claims clipped by neighbours, deterministic prey. Terrain is invented. Not a population-viability model.