Shorebirds Harassed by Off-Leash Dogs

by Paul Donahue

Sanderlings are just one of the shorebird species that spend part of the winter in Pacifica. Over just the past decade, the use of Pacifica State Beach/Linda Mar Beach by Sanderling during their non-breeding season has dropped dramatically. During this same time period, human use of the beach has increased. In particular, the running of off-leash dogs on the beach has increased.

Sanderling feeding along the edge of the tide.

The real threat to the shorebirds from dogs is not that the dogs are going to catch and kill them. Dogs are way too slow to capture anything other than sick or injured shorebirds. The danger is in how the dogs affect the energy balance of the birds. Shorebirds, like most wild creatures, exist on a fairly tight energy budget. There is a small amount of slack built into the system, but not a lot. Anything that negatively impacts that energy balance threatens their physiological well-being.

All dogs on beaches disturb shorebirds. It has been repeatedly documented that their mere presence is enough to stress the birds and impair their foraging efficiency. Beyond that, off-leash dogs that actually chase the birds are considerably worse. Not only do these dogs interrupt the foraging and resting time of the shorebirds, but in flying around to escape dogs, the birds burn off calories and expend large amounts of energy they can’t afford to spare.

Consequently, the populations of these shorebirds eventually suffer because the winter survival rate drops due to the poorer physiological condition of the birds. Beyond that, the nesting success of the birds in summer is negatively impacted by their poorer physiological condition through the previous winter. Lower winter survival rates coupled with lower reproductive success slowly but steadily shrink the population. Sanderlings have experienced about an 80% decline in their numbers since the early 1970’s. 

While dog owners may delight in watching their pet chasing shorebirds up and down the beach, they are doing considerable harm to these vulnerable birds. Imagine your own stress level, how little you would get to eat, and how many calories you would burn if you were chased around all day long by hungry lions…if every time you settled down at the table another lion came charging across the room. After several months of that, would you be in any sort of physiological or psychological condition to undertake a dangerous 2000+ mile northward migration and then expend large amounts of energy raising a family? Of course you wouldn’t, and neither are Sanderlings that are subjected to constant harassment by dogs on our sandy beaches.

Pacifica, California
December 2015


from: Pacifica Tribune, page B3, week of Dec 30, 2015-Jan 5, 2016