Fig. 1. Experimental design – focal males were introduced in the experimental set up 2 days before the operation for habituation. On day 0 males were operated creating
sham, castrated or urine bladder damaged males. Male interaction with neighboring females was observed for 10 min each day. Nest presence and male nuptial coloration
were registered daily. On the day 9, focal males were exposed to a territorial neighboring male and the behavior of the focal male was recorded for 15 min. Blood samples
were collected on days 0 (before operation), 4 and day 8 – (after the interaction with the neighbor male).