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Fig. 2. Description of number of parameters (K) and AICc for various models testing
for an effect of bromocriptine treatment on kidnapping behaviour in emperor
penguins. Model 1 is the general starting model, with an effect of treatment
and behavioural state on survival and sighting probabilities and an effect of
treatment on transition probabilities. Model selection: an arrow starting from
a model indicate the application of a constraint to this model. This
constraint is detailed above the constrained model, which is at the end of the
arrow. 
AICc values were used to determine which model provides the best
description of the data based on the fewest parameters (AICc=AICc of
the starting model–AICc of the constrained model). AICc values
>2 indicate that the constrained model is preferable. AICc values
<2 and >–2 indicate that models are fairly similar and the model
including the fewest parameters was selected. AICc values <–2
indicate that the starting model is preferable. Filled and broken arrows
indicate, respectively, that the constraint was selected or not. Each model
was defined using the following notations: S, survival probability;
P, sighting probability; 
ab transition probability
from state a to b; 1, non-kidnapping state; 2, kidnapping state;
12br/12co, 12 within the
bromocriptine/control group; treatment/state: effect of treatment/behavioural
state on a given parameter; prl: effect of initial level of PRL on a given
parameter; 12first122-7,
effect of time since treatment on 12, which can vary between
the first day and the last days of the study period. In models testing for an
effect of PRL levels or time since treatment on 12 within one
group (bromocriptine/control), 12treatment was
dissociated and we used this notation 12br
12co. Models A and B are two nested models allowing us to test
an effect of treatment on kidnapping behaviour during the first day of
behavioural monitoring.
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