1. Multi-state Occupancy

2. Multiple Occupancy States Rather than just presence/absence of the species at a sampling unit, ‘occupancy’ could be categorized into multiple states. breeding/non-breeding/absent Key assumptions are: highest order state must be observable without error. ambiguity associated with observed lower order states. true state does not change within a season (closure).

3. Multiple Occupancy States Single Season Study 3 states 0 = not occupied 1 = non-breeders only 2 = at least some breeders Breeding state cannot be identified with certainty Observed state = 2: detection of breeding, evidence is unambiguous (true state = 2) Observed state = 1: no detection of breeding, evidence is ambiguous (true state = 1 or 2) Observed state = 0: no detection (true state = 0, 1, or 2)

4. Multiple Occupancy States: Parameters Pr(unit i is in state m ) Pr(observe state l in survey j of site i | true state = m )

5. Multiple Occupancy States: Parameters Observed State True State012 0100 10 2

6. Multiple Occupancy States: Reparameterizations Pr(unit is occupied) Pr(unit is in state 2|unit is occupied) Pr(species is detected|true state = 2) Pr(correctly classify as being in state 2)

7. Multiple Occupancy States: Detection History Modeling Pr(species is detected|true state = 2) Pr(correctly classify as being in state 2)

8. A Probabilistic Model The combination of these statements forms the model likelihood: Maximum likelihood estimates of parameters can be obtained. However, parameters cannot be site-specific without additional information (covariates).

9. Multiple Occupancy States: Cal. Spotted Owl Reproduction Eldorado National Forest, 2004 2 states for each occupied territory: Successfully reproduced Did not successfully reproduce Multiple (5 maximum) visits with “mousing” Definitive evidence of reproduction: Detect young (e.g., moused adult feeds young) Much more likely later in season (last 3 visits) Nichols et al. (2007) and MacKenzie et al. (2009)

10. Multiple Occupancy States: Cal. Spotted Owl Reproduction Naïve estimate: Parameter estimates from model

11. Multiple Occupancy States: What you should know… Multiple states with uncertain state assignment represent a natural extension of occupancy models Key parameters of the model Provides a framework to address interesting ecological questions from population-level data