Hi Paulo,

I guess that we do not know much about the wintering behavior of tree roosting bats, because not many people are checking bat boxes in winter. We started looking in bat boxes in December during a winter low and found lots of pipistrelles and a leisler's noctule.

(https://www.researchgate.net/publication/275522730_Winterbeobachtungen_von_Zwergfledermusen_%28Pipistrellus_pipistrellus%29_und_Kleinabendseglern_%28Nyctalus_leisleri%29_in_Fledermausksten_im_Naturschutzgebiet_BodetalNO-Harz_%28Sachsen-Anhalt%29)

I think the tree roosting bats are more often active than cave dwelling bats. So, bat boxes can be used just from time to time, depending on the climate conditions and we just do not notice it.

All the best,

Marcus.

Article Winterbeobachtungen von Zwergfledermäusen (Pipistrellus pipi...

Paulo:

what is your need for this aspect of occupation speed? Are you pointing for concrete bat taxa?

Usually the boxes are placed for a long period in order to

Considering the second aspect,  the season in which you install the box would of course have influence to the species being the first to settle (tree dwellers during winter as Marcus told, cave dwellers only in summer), but on the long view, this will not primarily affect the acceptance of expected "visitors" in future.

If you intend to install the boxes for selected species (may be a special case of 1.) there may be a species depending seasonal preferation to start with the boxes - you should synchronize your efforts to the hibernation cycle of the species investigated.

All the best,

Ernst-Hermann

Thank you very much Marcus & Ernst-Herman!

Hi Paulo:

For my experience in the south of Spain, usually the bat-boxes do not have presence of bat untill two-three years after.

When I put bat-boxes, usually I installed the boxes in winter. I hoped that they were occupied in spring-summer, but they had presence in winter of the second and third year.

The specie present was Pipistrellus kuhlii. 

Fulgencio,

Assuming the bat-boxes don’t have presence of bat until two-three years after, wouldn't more success putting bat boxes in the spring-summer? The fact of placing a new thing in the environment (in the peak of activity) maybe the bats would be more curious and occupy the bat-boxes early...

Paulo,

The idea was to put the bat-boxes in winter and when the bats looked for a new breeding roosts and that way they explored the bat-boxes. But they did not think like us.

I think that first the bax-boxes are occupied by solitary bats in winter and then, if they consider like a good breeding roost, it is occupied by the colony. For this, the bat-boxes are occupied after two or three years.

In the other hand, do you think that they need bat-boxes? I think that if they have old roosts, using long time, the bats do not change easily. You know that the bats usually do not change their roosts.

This is a interesting issue because you must to check if they want to change. Probably, the occupancy ratio could depend of this. It is a idea.

Yes Fulgencio, of course the bats do not change easily unless they are disturbed and It’s still unclear the impact of the bat-boxes in the bats conservation. However the installation of bat-boxes can be important compensatory measures (one of few) when we can’t avoid destruction their natural/usual roost (e.g. restructure/restoration houses, destruction of structures like old bridges and water mills and deforestation).

Hi altogether,

additional to Fulgencio's remarks (which fully fit with our observations here) I would like to mention that new boxes usually are not accepted at once -it takes a couple of seasons until we find the first bats roosting there. So we place the boxes in autumn in order to let them be "weathered" before the season starts....

Cheers,

Ernst-Hermann

Hi,

to get a "quick occupation" we use a bit of the feces from old boxes or colonies and inoculate the new boxes.

This year, there was made a kind of a water-feces-solution from P.nathusii and inoculated the new boxes in January. In the migration period in March the boxes were quickly occupied.

Regards,

Marcus.

Very interesting Marcus!

Thank you for sharing this experience.

Kind regards

Hi Paulo,

actually this would be an interesting aspect to investigate and I can easily imagine how to set up an experiment. I fully agree with colleagues' remarks about the usually long colonisation times and the opportunity of exposing the bat box to environmental agents to make it "more natural" and encourage bats to explore it. A common rule of thumb is to place them in early spring but I can't see any problem with doing it in the preceding winter (provided your target is summer occupation, a longer exposure to weathering could only favour it).  All best, Danilo

Thank you Danilo.

Best regards