Serializador de coleção personalizada MongoDb

public class MyListAnimalSerializer : SerializerBase<List<Animals>>
{
    public override void Serialize(MongoDB.Bson.Serialization.BsonSerializationContext context, MongoDB.Bson.Serialization.BsonSerializationArgs args, List<Animal> value)
    {
        context.Writer.WriteStartArray();
        foreach (Animal mvnt in value)
        {
            context.Writer.WriteStartDocument();
            switch (mvnt.GetType().Name)
            {
                case "Tiger":
                    //your serialization here
                    break;
                case "Zebra":
                    //your serialization here
                    break;
                default:
                    break;
            }
            context.Writer.WriteEndDocument();
        }
        context.Writer.WriteEndArray();
    }

    public override List<Animals> Deserialize(MongoDB.Bson.Serialization.BsonDeserializationContext context, MongoDB.Bson.Serialization.BsonDeserializationArgs args)
    {
        context.Reader.ReadStartArray();

        List<Animals> result = new List<Animals>();

        while (true)
        {
            try
            {
                //this catch block only need to identify the end of the Array
                context.Reader.ReadStartDocument();
            }
            catch (Exception exp)
            {
                context.Reader.ReadEndArray();
                break;
            }

            var type = context.Reader.ReadString();
            var _id = context.Reader.ReadObjectId();
            var name = context.Reader.ReadString();
            if (type == "Tiger")
            {
                double tiger_height = context.Reader.ReadDouble();
                result.Add(new Tiger()
                {
                    Id = id,
                    Name = animal_name,
                    Height = tiger_height
                });
            }
            else
            {
                long zebra_stripes = context.Reader.ReadInt64();
                result.Add(return new Zebra()
                {
                    Id = id,
                    Name = animal_name,
                    StripesAmount = zebra_stripes
                });
            }
            context.Reader.ReadEndDocument();
        }
        return result;
    }
}

[BsonSerializer(typeof(MyListAnimalSerializer))]
public List<Animal> Animals { get; set; }