.NET Fiddle

CSharp · Console

/Program.cs

using System;
using System.Linq;
using System.Xml;					
using System.Xml.Linq;
using System.Collections; 
using System.Collections.Generic;
using System.Data;
using System.Data.DataSetExtensions;
using System.Data.Linq;
using System.Text;
using System.Text.RegularExpressions;
using System.Xml.Serialization;	
using System.IO;
using System.Globalization;
using System.Diagnostics;
					
public class Program
{
	public static void Main()
	{
		   var dictionary = new Dictionary<string, int>(5);
        dictionary.Add("cat", 3);
        dictionary.Add("dog", 1);
        dictionary.Add("mouse", 0);
        dictionary.Add("elephant", 2);
        dictionary.Add("bird", 4);
		
		var result = dictionary
			.Take(1)
			.Concat(dictionary
					.Skip(1)
					.OrderBy(o=>o.Value))
			.Select(x=>x.Key);

		result.Dump();
	}
}