Supplemental Water Helps Birds During Drought

Supplemental Water to Help Birds during Drought 

By Andy McCormick 


As climate change progresses periods of drought are becoming more common. Even in rainy Washington drought is a problem. As of June 3, 2019, Governor Jay Inslee had expanded the state’s drought emergency declaration to include 27 watersheds, nearly half of the state’s area. Although the primary concerns for water management in Washington are for farming and salmon migration, birds and other wildlife are also affected, and they may need assistance to cope with the increasing dryness in some areas.  

This need for supplemental water by birds was highlighted in a study recently published in Western Birds, the journal of the Western Field Ornithologists. Researchers compared two areas of coastal sage scrub in Los Angeles County, California to see if species richness would decline during periods of drought. They found two patches of coastal sage scrub that had multiple years of bird survey data accumulated by local birders.  

The first area was the Voorhis Ecological Reserve near Pomona. This location lacks permanent water but is near areas with artificial ponds and watered landscaping. Two canyons in the reserve had a total of 265 surveys conducted from January 1983 to December 2003. The second area was the Bernard Field Station near Claremont. This area had an artificial pond and wetland which are managed as a source of permanent water for wildlife. Monthly bird surveys had been conducted at the field station from 2000 to 2014. The research team replicated both surveys on a twice-weekly basis during a period of drought from February 2013 to February 2014.  

The results indicated that the numbers of all species of birds: year-round residents, winter migrants, summer migrants, and transients were higher at the Bernard Field Station than at the Voohis Ecological Reserve. During periods of drought at both locations, the number of species was lower than during wet periods, but the decline in resident birds was greater at the Voorhis site. The number of both resident and migrant birds was higher during drought at the Bernard site than at the Voorhis site. The researchers inferred that the supplemental water source at the Bernard site may have helped alleviate the drought stress for the resident birds and provided water for the migrating birds.  

Migrating birds have the option of flying past a site to locate more water during periods of drought. Resident birds will also seek out water, but in an urbanized environment they will have fewer options. Extended periods of drought will also repress reproductive output and reduce population size in resident birds. 

The importance of water was underlined in this study by the finding that species richness at the Bernard site was greater during periods of drought as birds were likely attracted to the supplemental supply of water. Providing supplemental water for wildlife during periods of drought may be an important component of resource management as periods of drought may increase in intensity and duration in some regions as a result of climate change.