Previously we proposed a new reconnaissance method for estimating the total abundance of small mammals in urban areas. The method includes placing plastic bottles with bait inside equal distances apart. In this research we examined two ways to improve the method: using bottles of smaller volume (0,25 liters instead of 0,5 liters) to increase the ergonomics and using opaque bottles to make them more attractive for animals. Bigger and smaller bottles with neck diameter of 38 mm were fastened in pairs which were set in a transect with a fi ve-meter spacing. The same was done with pairs of opaque and transparent bottles. A bait (rye bread with unrefi ned sunfl ower oil) was put into all the bottles. During the following days we recorded animals’ visits into the bottles. It was found out that there are no signifi cant diff erences in how often animals attend bottles of 0,25 liters and 0,5 liters, the same results were received for both transparent and opaque bottles. Thus, the simple method for estimating abundance of small mammals may be optimized by using smaller bottles, the colour of which is not important.