If you want to do this, you can create a new filter in your functions.php overriding the filter of this plugin.
Put this in your functions.php:
function my_bxcft_get_field_value( $value, $type, $id) {
if ($type == 'birthdate') {
$value = str_replace("<p>", "", $value);
$value = str_replace("</p>", "", $value);
$field = new BP_XProfile_Field($id);
// Get children.
$childs = $field->get_children();
$show_age = false;
if (isset($childs) && count($childs) > 0) {
// Get the name of custom post type.
if ($childs[0]->name == 'show_age')
$show_age = true;
}
if ($show_age) {
return '<p>'.floor((time() - strtotime($value))/31556926).'</p>';
}
return '<p>'.date_i18n( 'F j' , strtotime($value) ).'</p>';
}
return $value;
}
add_filter( 'bp_get_the_profile_field_value', 'my_bxcft_get_field_value', 15, 3);
It will override the filter from the plugin and show only the day and month of birthdate. If you want to change the date format, you need to change this line:
return '<p>'.date_i18n( 'F j' , strtotime($value) ).'</p>';
F => Name of month.
j => Day.