Dusk on a bombing range

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Locating a research site inside a bombing range might seem crazy, but it is what my friend Max is doing for his doctoral research. He works in a portion of the Barry M. Goldwater Range in western Arizona managed by the Marine Corps Air Station Yuma. The area is relatively pristine and well managed because of the military presence, and active bombing hasn’t been carried out nearby for years. Plus, the ‘unexploded ordnance’ signs help to deter the Border Patrol officers from driving all over his research sites. I recently had the chance to visit this place as neither scientist nor soldier, but rather as a botanical tourist.

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The vast sand dunes west of the Mohawk Mountains are an extension of the Gran Desierto de Altar, primarily located in Sonora, Mexico. The environment looks harsh and inhospitable, but it actually holds a surprising amount of life. Stone artifacts and petroglyphs indicate long-term human habitation, but the place really comes alive after a good set of winter rains.

The dunes can store a large amount of moisture, and it is this moisture that in rare years enables a beautiful winter bloom. Plants that have persisted via roots or seeds for many dry years seize the available water resources and put all their effort into flowering.

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Dusk is the time when these ephemeral blooms are most spectacular. Many species have flowers that only open at night – their pollinators are not day-active, and perhaps the heat of the day would lead too too much water loss in delicate petals. My favorite species is Oenothera deltoides, a white-petaled evening-primrose.

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This species is visited by crepuscular hawkmoths (here probably Hyles lineata). At dusk the sky darkens with these hummingbird-size insects, and a soft flapping sound fills in the air. It is utterly magical, and one feels like an intruder into a hidden ecological dance.

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The next morning a dusty sunrise came. With the heat of the day the flowers closed, and the moths were long gone. Many flowers looked bedraggled, and finished for the season. The spring bloom lasts for only a few days, and comes only in rare years. It is a marvelous secret for a bombing range to hold.

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