Default values when using 2 locales
It's not possible to have different defaults per locale with the Table field type. Also keep in mind that the content from the first locale you edit is copied over to all other locales on the first save.

But how about using numbers for the months in the table and to show the full month names in your templates get them from craft.i18n.getLocaleData:

{% for row in myTableField %}
    &lt;li&gt;
        {{ craft.i18n.getLocaleData().getMonthName(row.col1) }}:
        {{ row.col2 }}
    &lt;/li&gt;
{% endfor %}


Another way would be to use the date filter:

{{ ('2015-' ~ row.col1 ~ '-1')|date('F') }}