Did Buchanan Plagiarize this World War I Blockade Map?

Did Buchanan plagiarize a map from Martin Gilbert?

In Patrick J. Buchanan’s Churchill, Hitler, and “The Unnecessary War”, he uses a map to show the food riots in Germany during World War I of which he blames Winston Churchill as the cause. There is another map in Martin Gilbert’s Atlas of the First World War that is very similar.

Similarities

Similar topic: “Starvation Blockade” and “Food Riots”
Exact same region focus
Same keys on the lower right-hand side: Number of deaths and dots representing food riots

Here is Buchanan’s map from 2008, rebranded as “The Success of Churchill’s Starvation blockade.”

Patrick J. Buchanan’s Churchill, Hitler, and “The Unnecessary War” (New York: Crown Publishing Group, 2008), 78.

Here is Martin Gilbert’s map from his Atlas of the First World War, which has been in print since 1970.

Martin Gilbert, The Routledge Atlas of the First World War, 2nd ed. (New York: Routledge, 2002), 77.

No attribution is given to Gilbert in Buchanan’s work.