Bleeding Heart Doves are definitely not colony birds, strictly one pair per aviary. They are totally non-aggressive to any other species that I have kept them with, but I have not tried them with any ground birds. In fact, I have had them seriously bullied by Barbary Doves, which can be very aggressive when nesting.
They are mainly a ground-dweller, although they will fly up to feed from a shelf, and they roost up, of course. One thing I particularly like about them is that they can become very tame. They do not feed from the hand, but you have to watch where you step in their aviary, as they tend to get under your feet.
Although basically seedeaters (white millet being very important) they also take softfood and perhaps some diced fruit. They are particularly fond of mealworms and mine come running each evening, when I usually throw a few into each aviary. I have found them to be just about winter hardy, but the winters here are not too severe these days. If your aviaries have Shelters attached that should be fine (mine don't), they should not need extra heating. On really cold days I must admit that I can feel a bit guilty about them, as they sit down a lot, presumably to avoid losing heat from their legs. So far I have never lost one during the winter, but they must have a dry area in the aviary. I feel that it is better to leave them in the aviaries, as they do not do well in cages.
Sexing them is not all that easy, although cocks do tend to be a bit larger than hens and the 'heart' slightly more extensive. It is not too difficult to distinguish the sexes in a definite pair, but not always easy otherwise, unless you catch a cock displaying. Apparently it has been suggested that you can also sex them by eye-colour (the cock being bluish and the hen more purple, I think) but I have never been able to see this. The cocks can be aggressive to their hens, if the latter are not ready to nest. In the cases of the two hens I had killed, one was with a pair that I had been holding for a couple of weeks in a small indoor flight. There had been no sign of trouble until one morning I found that the hen had from the top of her head to the base of her tail completely stripped of feathers and turned into a bloody pulp. The second case was of a pair that had been breeding together for a couple of years. Late last summer there had been some night problem and the hen damaged a leg and could only just walk for a couple of days. Just as she was improving the cock must have cornered her and again I found here savagely beaten. In retrospect, I should have separated them ............!
Last Friday saw one hen lay her first egg of the year. They are sitting now, so I can but hope. Early eggs are not all that successful and at times they are not the best of parents anyway. At times I have resorted to using Barbaries as fosters and they usually produce a better quality fledgling, larger and more vigorous. The newly hatched chicks are a bit smaller than Barbaries and I find it useful to have a spare egg in the nest for the first few days, to prevent the chicks from being squashed.