Bat roost replacements 'not being used'
A study has found that most roosts provided to compensate for the effect of building developments on bat colonies are not being used.
The Scottish Natural Heritage report looked at dozens of sites across Scotland.
It concluded that, in the short term at least, usage levels at many locations were low with some not used at all.
The study advised further examination of the longer-term impact and looking at improving wider bat landscapes.
SNH took over responsibility for granting licenses for developments affecting bats and roosts in 2011.
By the end of 2014 it had issued more than 400 licences.
Many of them have seen work adapted to minimise the impact on bats but - where it cannot be avoided - compensation measures like the provision of boxes or lofts are introduced.
However, monitoring carried out last year suggests that these are not having the desired effect.
Less than 20% of sites had evidence they had been used by a maternity colony and 60% showed no evidence of use by bats at all.
The report recommended further studies to look at the long-term impact of roost closure and forced movement.
It also suggested improving knowledge of the reasons why compensation sites succeed or fail.
And it called for the identification of "priority areas" for bat conservation that might allow any replacement facilities to be placed in the "optimum location" in the wider landscape.
"The results of this study show that the majority of roosts provided for maternity colonies as compensation for loss and/or damage of a roost through development work are not being used (at least in the short-term)," the report said.
"This has implications for the assumption that if compensation is provided the impact on a species favourable conservation status will be negated.
"The results of this study indicate that retained roosts are most likely to be occupied by maternity colonies but further long-term studies with increased sample sizes and improved detail are needed to determine why some roosts are used and not others."