Muhalnitsa

”Muhalnitsa” () is a protected area in western Bulgaria, located at one kilometre south of the town of Botevgrad and at 63 km north-east of the capital Sofia. It is situated in the Botevgrad valley in the western section of the Balkan Mountains. ”Muhalnitsa” was established in 1992 to protect a unique breeding migration of the common frog (Rana temporaria).

== History of the site== On 14 February 1968 zoologist Vladimir Beshkov discovered several hundred common frogs (Rana temporaria) in a small swamp at an altitude of 360 m near the town of Botevgrad which was very unusual for this species at such a low altitude. On 1 March and 4 March 1971 he marked several hundred specimens and released them back into the swamp. On 4 June 1971 one of the marked frogs was found on the slopes of the Bilo mountain at a distance of 4925 m on a straight line from the swamp and at 875 m.a.s.l. After a hiatus of several years, Beshkov renewed his studies in 1979, when between 31 January and 3 March, 457 common frogs were marked in the swamp. Frogs were also marked while moving down the rivers in February and March 1980 at 5.5 and 6 km above the swamp, high in the Bilo mountain. On 11 March 1980 two of them were found in the “Muhalnitsa” swamp (one 4, the other 11 days after marking). Beshkov published his research in a series of scientific and popular science papers which served as a basis for the establishment of the area from the swamp to the Old (Zelin) River as a protected area in 1992