Your questions raise a few different issues -- conditions in dry v wet season, timing of oestrus, dominance behaviour -- and I will try to give you some answers, from the area where I have SOME expertise, i.e. feeding ecology and demography. I will let others the opportunity to comment on social behaviour and competition.

So... about dry seaons and elephant condition. We have seen year after year in Amboseli that the elephants become increasingly quiet and conservative as dry seasons progress and food gets scarce, and in drier years this is more pronounced. They are conserving energy, as their body condition declines in response to reduced food quality and quantity. In contrast, when it rains and the grass grows tall and nutritious, the elephants quickly regain their condition and energy, interact and play, come into oestrus and musth, make a lot of noise and just generally carry on. In years whe there is more rain and/or a longer wet season, these high spirits can last longer into the months of Msy, even June, while in years when the rains stop early, as happened this year in Amboseli, the "fun" stops earlier and the elephants put their heads down and try to get through until the rains come. This contrast in conditions can be found between places, as well as between different seasons or years; so if Tsavo had longer rains and better food -- does anyone know about Tsavo this year? -- the elephants there would still be in good shape, with lots of energy and mating, compared to those in Amboseli. When was your visit, Jan; what months and what was the vegetation like? Still green?

As for more competition and chasing at waterholes in Tsavo, I would agree with your suggestion. Yes, there would be more interaction over access to waterholes where they are restricted, compared to the wider access that elephants enjoy in Amboseli. And certain vocalizations could be pronounced, but here I would defer to Joyce.

I hope that these few off-the-cuff comments help you. It's v interesting to hear about differences between populations, as it puts our work in Amboseli in a broader context, and helps us understand better the "rules" of elephant ecology and behaviour.

Keith