From 1999 until 2006 (with addition of some data of 2006) there were targeted large-area investigations on the occurrence and distribution of the Eurasian Treecreeper (Certhia familiaris macrodactyla C.L. BREHM, 1831) and the Short-toed Treecreeper (Certhia b. brachydactyla C.L. BREHM, 1820) in the area of the “Mittelelbe” (former district Wittenberg, 51.50° N, 12.50° E), from the southern rim of the “Roßlau-Wittenberger Vorfl äming” to the northern rim of the “Dübener Heide”, including the River Elbe valley (topographic maps 4041, 4042, 4141, 4142, 4241, 4242 and 4342). In 220 minutes fields convenient for settlement (462 km² = 86.6 % of the area) the occurrence of the species was tested by playback experiments at 778 checkpoints. A total of 2458 excursions on 1107 days (distributed over all months) led to 663 successfully controlled checkpoints. In 183 minutes fi elds territorial Eurasian Treecreepers (n=1423) were found and in 210 minutes fields there were territories of Short-toed Treecreepers (n=2048). In 1038 cases a syntope occurrence of Eurasian and Short-toed Treecreepers was detected in 177 minutes fi elds (588 checkpoints). A total of 661 Eurasian and 1262 Short-toed Treecreepers were mist-netted, measured and ringed with rings of the Hiddensee bird ringing centre. 66 Eurasian and 140 Short-toed Treecreepers were re-captured once or several times at the ringing site. The breeding stock of the Treecreepers in the former district Wittenberg is estimated at 1600 to 1800 breeding pairs of the Eurasian and at 2200 to 2500 breeding pairs of the Short-toed Treecreeper, respectively. In relation to the overall area (about 610 km2) the breeding density is 2.6–3.0 pairs/ km2 in the Eurasian and 3.6–4.1 pairs/km2 in the Short-toed Treecreeper, revealing a proportion of 1.44:1 (Eurasian: Short-toed Treecreeper). Whereas the medians of breeding density between Eurasian and Short-toed Treecreeper do not signifi cantly differ in coniferous forests (Mann-Whitney-U-Test, p > 0.05), differences in deciduous forests are signifi cant (M-W-U-Test, p