To beat or not to beat: Behavioral plasticity during the antler growth period affects cortisol but not testosterone concentrations in red deer (Cervus elaphus) males

The effects of challenge or social buffering on cortisol, testosterone, and antler growth in captive red deer (Cervus elaphus) males

“…The fact that increasing body weight was associated with an increase of C concentration may reflect an increasing energy demand of larger individuals, as previously shown in the red deer 15 , 49 . On the other hand, the increasing T concentrations associated with decreasing C concentrations are difficult to explain.…”

“…The food piles were tipped from the wheelbarrow in 8 or 9 piles about 2 m apart, in order to encourage competition without exacerbating it. This method has already been proven valid in previous studies e. g., 15 , 49 , etc. Each observation session took place in the morning (between 9.00 a.m. and 11.30 a.m.) and ranged from 20 to 60 min (depending how long the deer stayed at the site of supplementary feeding).…”

“…This strongly supported an effect of a challenging encounter, as anticipated 16 , 46 , 47 . In another study in the same herd, we have found that even though individual males had shown some plasticity in their behavioural response, the style of their individual inclination towards interaction had been maintained over three consecutive years despite the experimental modifications of the social environment 49 . Thus: those who tended to be aggressive against others were aggressive in any social situation, while those tending to avoid conflict also maintained this strategy in any social conditions.…”

“…However, some pairs of males consistently avoided each other even when aggregated during supplemental feeding. The reason why some males tended to keep in proximity with others or not could have been based on their personality 49 , inter-individual relationships and previous experience 50 , laterality of brain function and/or actual physical condition 51 .…”

“…We have previously shown that antler size has high repeatability in subsequent seasons during ontogeny 56 . Moreover, even though the males had shown behavioural plasticity, their individual attitude to seeking or avoiding interaction had been maintained despite the modifications of the social environment 49 .…”