How to extract some data from a collection using lambda/linq to objects?

IList<Aniamls> chickens;
IList<Animals> farmAnimals; // only contains the cows and sheep, now.

public abstract class Animal {}

public class Chicken : Animal {}

var chickens = animals.OfType<Chicken>().Cast<Animal>().ToList();

var nonChickens = animals.Except(chickens).ToList();

var chickens = new List<Animal>();
var nonChickens = new List<Animal>();

foreach(var animal in animals)
{
    var list = animal is Chicken ? chickens : nonChickens;

    list.Add(animal);
}

var chickens = farmAnimals.ToList().FindAll (c => c.Type == "Chicken");
farmAnimals.RemoveAll(a => a.Type=="Chicken");

var chickens = farmAnimals.Where(a => a.GetType() == typeof(Chicken)).ToList();
farmAnimals = farmAnimals.Where(a => a.GetType() != typeof(Chicken)).ToList();