@Mr Gharial The Winter Garden currently only houses butterflies and some goldfish in a couple of ponds. In the past there used to be exhibits in there for invertebrates, amphibians and callitrichids, but those have all since been removed.
To my knowledge no species have ever been kept free-roaming in this house. Not sure what the reason for that is.
@Mr Gharial The butterflies are housed in the winter garden from April to October, so from Spring to Autumn and during the entire summer.
During the later autumn, winter and early spring there are simply none around, as they just naturally die off when their short livespans end and replacements in the form of chrysalises (I believe imported from farms in Costa Rica) are not brought in during those months.
@Mr Gharial It may seem less strange when knowing that this building has actually never been built to house animals in the first place: it is a historical greenhouse dating back to 1898 that was meant to accomodate a botanical collection of tropical plants, and that is still the primary function of the building. I don't know a lot of plants, but it is said that some of the plants in here are quite rare, which is probably a reason why they don't keep free-roamers in here. The butterflies are a fairly recent addition, only introduced for the first time in 2015.
These are also two of the reasons why the butterflies are not kept in winter: the heating costs needed to accomodate butterflies during that season would be too high in a building as old as this one, and I have also read once that too much artificial heating isn't beneficial for the plants. This was apparently also one of the reasons why they removed the invertebrate terrariums and callithricid enclosure that were added here in 1990's or early 2000's during a restauration process in 2014.
Personally I regret the disappaerance of the callithricids : as they were no free runners, they couldn't harm the vegetation. Their removal had more to do with a certain historical correctness : as Valvas already said, this house was never built for animals. So the external and internal exhibits for golden lion-headed tamarin and others were removed. I personally think that is a wrong way of dealing with historical zoo buildings: they should be kept ofcourse but they should not necessarily used in their original function. With a couple of carefully chosen bird species and 1 small monkey exhibit this house would be really alive.
