A fladry line is essentially a line mounted along the top of a fence, from which are suspended strips of fabric or some other material which will flap in a breeze, and intended to deter wolves from traversing the fence-line. Fladry lines have been used for this purpose for several centuries. They are effective, but only temporarily, as the novelty may soon wear off. This technique is sometimes also used to alert horses and cattle to the presence of a fence, as the use of smoothwire fences and one strand of electric may not be seen by an animal unfamiliar with a new home.

Direct quote (need to summarize) from http://www.doubletongued.org/index.php/dictionary/fladry/: fladry n.pl. a string of flags used to contain or exclude wild animals. Also attributively: fladry line, fladry barrier. Subjects: Polish, Environment Editorial Note: In English fladry tends to be used in the plural only, meaning you can have “some fladry,” very rarely “a fladry,” and never “some fladries.” In French, however, des fladries is acceptable. The word is also used in German and Italian. Etymological Note: According to Polish Scientific Publishers (Wydawnictwo Naukowe PWN, SA), fladry is the plural of flader, which comes from German. It is not specified which German word, but it’s probably related to flattern ‘to flutter.’ It is probably not related to the Polish flądry, the plural of flądra, which according to the Oxford PWN Polish English Dictionary (2002, Oxford University Press) means “1. flounder, flatfish; 2. slattern, slut.”