For the table body’s column, we need to make sure that the birthday is only show if it is actually set:
```smarty
-<td class="columnDate columnBirthday">{if $person->birthday}{@$person->birthday|strtotime|date}{/if}</td>
+<td class="columnDate columnBirthday">{if $person->birthday}{$person->birthday}{/if}</td>
```
<templatelistener name="personListBirthdayColumn">
<eventname>columns</eventname>
<environment>admin</environment>
- <templatecode><![CDATA[<td class="columnDate columnBirthday">{if $person->birthday}{@$person->birthday|strtotime|date}{/if}</td>]]></templatecode>
+ <templatecode><![CDATA[<td class="columnDate columnBirthday">{if $person->birthday}{$person->birthday}{/if}</td>]]></templatecode>
<templatename>personList</templatename>
</templatelistener>
<!-- /admin -->