Why does this code have new in the collections indexer

Possible Duplicate:
“new” keyword in property declaration

Pardon me if this is C# 101, but I am trying to understand the code below:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Collections;

namespace Generics
{
    class RabbitCollection : ArrayList
    {
        public int Add(Rabbit newRabbit)
        {
            return base.Add(newRabbit);
        }

        //collections indexer 
        public new Rabbit this[int index]
        {
            get { return base[index] as Rabbit; }
            set { base[index] = value; }
        }
    }
}

Why does the indexer have new in front of it? By the way, Rabbit is a class defined in another file. Thanks!