The Black-winged Stilt (Himantopus himantopus) belongs to the stilt family (Recurvirostridae). For easier understanding, it is often treated within a broader kinship – the large and diverse order of shorebirds (Charadriiformes). We cannot confuse it with any of the birds that live here. It is an exceptionally slender and elegant black-and-white bird with almost unrealistically long legs. Its pinkish-red legs are slender, as is its straight black bill. The underside of the body is dirty white, the wings and shoulders are distinctly dark. In males, the dark part of the body is truly black, while the wings and shoulders of the female lean somewhat toward brown. The male can also be recognized by more black on the head and nape, but this is not an absolute rule, as there are all transitions between light- and dark-colored birds. The Black-winged Stilt flies with an extended neck and legs that protrude far beyond the tail. In flight, it is clearly visible with the entirely dark lower and upper surfaces of the wing and the white remaining parts of the body. From the tip of the beak to the end of the tail it is 33 to 36 cm long, though the legs, which in flight extend about 15 cm beyond the tail, are not counted.
Njegova prehrana je odvisna od sezone – išče in lovi drobne živali, ki jih je ob danem času največ. Čez dan iz plitve vode in podlage spretno pobira odrasle žuželke in njihove ličinke, drobne rake, malo- in mnogoščetince, paglavce in ribje mladice. V času, ko hrane živalskega izvora primanjkuje, se loti tudi raznih semen.
Polojnik je selivka, ki v glavnem prezimuje v Afriki. Svojo družabno naravo najbolj izrazito pokaže prav na selitvi, ko se tudi več sto polojnikov zbere v jato ali na skupinskem prenočišču. Pa tudi v času gnezdenja (od aprila do junija) se varneje počuti v majhnih skupinah (do 15 osebkov), ki jih lahko opazujemo, ko si iščejo hrano. Njegovo gnezdo je skromno. V šop rastlinja napravi vdolbino ali pa na golih tleh skupaj znosi nekaj rastlinskega materiala. Najraje gnezdi v neposredni bližini območij z obilico hrane, na krajih z dobrim pregledom nad okolico. Ustrezen habitat za gnezdenje polojnika so plitva vodna telesa s sladko ali brakično vodo (mešanica morske in sladke vode), kjer peščena, glinena ali blatna podlaga ustvari nizke otočke – poloje. Pozimi se zadržuje na primer na velikih celinskih vodnih telesih, blatnih morskih obalah, deltah rek in v solinah.
Polojnik je občutljiv zlasti na nihanje vodne gladine v času valjenja, saj dvig vode v tem času pomeni propad jajc. Življenje mu otežujejo tudi izsuševanja močvirij in regulacije vodotokov, kjer se zadržuje.
