En mainactivity no detecta id

[Toletum]

Código:

package com.example.mipc.controlcria;

import android.content.ContentValues;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.EditText;
import android.widget.Toast;
import android.R;



public class MainActivity extends ActionBarActivity {

    private EditText et1, et2, et3, et4,et5,et6;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_list_item);

        et1 = (EditText) findViewById(R.id.et_ano);
        et2 = (EditText) findViewById(R.id.et_jaula);
        et3 = (EditText) findViewById(R.id.et_anillama);
        et4 = (EditText) findViewById(R.id.et_anillama);
        et5 = (EditText) findViewById(R.id.et_mutacionhem);
        et6 = (EditText) findViewById(R.id.et_anillahem);


    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement

        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }


}

Me da errores en:

et1 = (EditText) findViewById(R.id.et_ano);
et2 = (EditText) findViewById(R.id.et_jaula);
et3 = (EditText) findViewById(R.id.et_anillama);
et4 = (EditText) findViewById(R.id.et_anillama);
et5 = (EditText) findViewById(R.id.et_mutacionhem);
et6 = (EditText) findViewById(R.id.et_anillahem);