Did you see many nesting Warbling Vireos this year? How about Swanison’s Thrush, Yellow Warbler, or Western Wood-Pewee? I think something sad and sinister is happening on our local scene. The nesting birds we love and sometimes take for granted are disappearing right before our eyes and ears. This reality has become dramatically evident in recent years in many of the areas of riparian habitat of Santa Cruz County.

I will use an area near my Capitola home as an example. Over the last 15 years I have often visited the riparian corridor of Soquel Creek downstream of Highway 1. This section of the creek has tall cottonwoods and alders, dense willows and understory, live oaks, some sycamores and…not many breeding birds. At least not lately. A paucity of bird song has been strikingly evident over the last few years. This year I visited the area repeatedly, especially during early June, the heart of the local nesting season. The word that best describes the experience is silence. No indication of nesting Warbling Vireo, Yellow Warbler, Western Wood-Pewee, Swainson’s Thrush, or Black-headed Grosbeak, and fewer than expected Wilson’s Warbler, Pacific-slope Flycatcher, Wrentit, Spotted Towhee, and Song Sparrow. It is distressing to say the least to walk through tall, complex riparian forest at 8:00 a.m. on June 9 and not encounter a single Neotropical migrant, save some Violet-green and Rough-winged Swallows!

But that was my experience there, and I have observed the same dearth of nesting birds to lesser or greater degrees at many other spots in our county. Other active local birders have corroborated my observations, although none of us has studied the situation with detailed surveys. Still, the skilled ear of an observer with many years of local experience does not lie. Neotropical migrants have been in the conservation spotlight over the last decade, and while they are at the heart of the assemblage of locally disappearing birds, the apparent declines also extend to resident species like California Quail, Spotted Towhee, Song Sparrow, Wrentit and Downy Woodpecker.

A whole suite of nesting species appears to be declining at many different locations, with some species no longer even occurring at certain spots in the last few years. These locations include Scott Creek, Liddell Creek, Antonelli Pond, Younger Lagoon, Meder Canyon, Neary Lagoon, Sycamore Grove on the San Lorenzo, Zayante Creek, Branciforte Creek, Arana Gulch, un-named streams that feed into Schwan Lake, Rodeo Gulch, Soquel Creek, Noble Gulch, Tannery Gulch, Borregas Gulch, Aptos Creek, Hidden Creek, and Corralitos Creek. Some of these spots are in urban settings and likely impacted by human activities, but others are more or less natural.

Potential causes are numerous. They include local ones like removal of habitat, habitat fragmentation and isolation, increasing invasive exotic plants, increasing predation by feral cats and rats, cowbird parasitism, and others. But some areas where birds are declining do not seem to be much affected by these local causes. And don’t be too fast to pin things on the dreaded cowbird, because they are lacking in some areas or not reproducing much in others. Larger scale causes relating to regional population declines are undoubtedly at play, but are complicated to factor into the assessment of causality for changes in local bird numbers. I wonder also what effect recent losses of large areas of local riparian forest, such as the eight miles of riparian that was gutted at the Pajaro River in 1995, and other recent losses at the Salinas River, might have on populations in smaller neighboring riparian areas?

I cannot offer any solutions in this article. I only seek to raise our awareness of the developing situation. Maybe my observations are only of local effects, or short term changes, or even artifacts stemming from a lack of detailed field studies. Perhaps, and I hope so, but I doubt it. The accumulated evidence from recent years does not support those conclusions. We can only begin to unravel the causes  with some careful studies of our nesting bird populations in a variety of locations. The recent riparian survey undertaken by Point Reyes Bird Observatory is a step in that direction. However, all too often we are missing detailed information of bird numbers from the past, even 10 years ago, that is needed to assess population changes. Here the regular local birder can contribute by being aware of what species are present or not present, keeping field notes on numbers and breeding evidence for sites they visit, and reporting observations. Over the long term this sort of information gathered by “regular birders” becomes invaluable.

Isn’t it sadly ironic that folks are striving to preserve biological values in some of our riparian habitats that may be threatened by proposed projects (e.g., the Neary skatepark and the Redtree Properties development next to Soquel Creek), while the very birds that live there are slipping away? When my seven year old son is old enough to have an interest in learning the song of a Yellow Warbler, how far will I have to travel to help him find one?