Regex : trouver tous les mots de plus de 3 lettres entre deux autres mots

(?<=((birds?)|(pigs?)).*)\b[a-z]{3,}\b(?=.*((birds?)|(pigs?)))

http://regexstorm.net/tester?p=%28%3f%3c%3d%28%28birds%3f%29%7c%28pigs%3f%29%29.*%29%5cb%5ba-z%5d%7b3%2c%7d%5cb%28%3f%3d.*%28%28birds%3f%29%7c%28pigs%3f%29%29%29&i=Pigs+are+farm+animals.+Birds+are+not+%0d%0aMy+bird+fly+in+his+cage.+My+pig+run+in+the+garden.&o=i

\

Pattern pattern = Pattern.compile("(?<=((birds?)|(pigs?)).*)\\b[a-z]{3,}\\b(?=.*((birds?)|(pigs?)))",
    Pattern.CASE_INSENSITIVE);

String text = "Pigs are farm animals. Birds are not\n"
    + "My bird fly in his cage. My pig run in the garden.";

Matcher matcher = pattern.matcher(text);
while (matcher.find()) {
    System.out.println(matcher.group(0));
}

are
farm
animals
fly
his
cage

e résultat va étre are animals et also; or c'est faux.