13D Filing: Southeastern Asset Management and Deltic Timber Corp (DEL)

We are filing this Amendment No. 1 to signal our support for this unsolicited proposal and
to encourage other Deltic shareholders to express their views to the board and management for a better outcome than the status quo.

Among
other things, Southeastern may nominate directors at Deltics annual meeting.

As previously stated in the Schedule 13D, in addition
we may from time to time and at any time in the future, depending on various factors, take such actions with respect to our investment in the Securities as we deem appropriate at the time including, but are not limited to: (i) acquiring
additional Securities and/or other equity, debt, notes, other securities, including but not limited to derivative or other instruments that are based upon or relate to the value of the Securities in the open market, through private transactions or
otherwise; (ii) disposing of any or all of the Securities in the open market, through private transactions or otherwise; (iii) entering into agreements or understandings with other shareholders or stakeholders of Deltic with respect to the
voting, holding and/or disposition of Securities; or (iv) proposing or considering any one or more of the actions described in subsections (a) through (j) of Item 4 of Schedule 13D.

Signatures

After reasonable
inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Dated:
August 25, 2017

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