San Diego Natural History Museum--Your Nature Connection[San Diego County Bird Atlas Project]

WRENDERINGS
Special Reports
Summer 2002

Birdiest City
Chula Vista Nature Center Update
Atlas Dodged the Bullet of Drought

San Diego is America's Birdiest City for 2002!

You may have heard it said that the San Diego region enjoys more species of birds than any other county in the United States. Now there's some additional evidence that this is true.

A nationwide competition was held this spring, with the cooperation of the American Birding Association, to see which city could identify the most species of birds within its city limits in a 24-hour period. It was called the "America's Birdiest City" contest.

The sightings have been recorded, the lists have been totaled, and the results are official--for 2002 San Diego has proven itself to be America's Birdiest City, with 218 species recorded inside the city limits. Last year, New York City was the winner with 188 species. San Diego was close at 185 but, as the saying goes, this wasn't horseshoes.

The top five large cities for 2002 were: San Diego, 218 species, New York, 205 species, Corpus Christi, 188 species, Boston, 152 species, and Milwaukee, 146 species. Both the San Diego and New York totals were new city records.

A separate competition was held among smaller cities, and here the winner, America's Birdiest Small City, was Duluth, MN. The top small cities were Duluth, 183 species, Santa Cruz, CA, 170 species, and Newport Beach, CA, 155 species.

All of the participating cities had interesting sightings. In San Diego's case, the most unusual sighting was a Curve-billed Thrasher, normally found in eastern Arizona. It wasn't included in San Diego's total, as it was seen near the Mexican border, so there is some possibility it didn't get to San Diego entirely on its own.

San Diego counters also recorded four species of parrots, but only one, the Red-crowned Parrot, could be officially counted as it is the only one that is well established in southern California. The others are assumed to be escapees. Also not included were the spectacular Mexican Black-throated Magpie-Jays, now resident near the border, that most likely were originally escapees from Tijuana.

San Diego's improved results over last year's 185 species reflected a combination of favorable weather, as well as having many more observers in the field to cover bird "hot spots" such as the San Pasqual and Tijuana River valleys. It also didn't hurt that San Diego is strategically located on the Pacific Flyway and is one of America's largest cities in land area. The strongest correlation with the top results was how many participants were in the field. San Diego had about 45 observers, Duluth had 50, and New York around one hundred.

Several of the cities that participated combined their America's Birdiest City efforts with other worthwhile activities such as fund-raising birdathons for the Audubon Society, International Migratory Bird Day, and local migratory hawk watches.

Although the winners of the competition get "bragging rights" it should be emphasized that there are more practical applications for the America's Birdiest City results as well. These include use as an awareness and education tool for local residents, as the start of a time series of data on local spring season breeders and migrants, and (especially for the top cities) as a justification for increased local habitat protection.

The competition will be held again in the spring of 2003!

--Phil Pryde


Update from Chula Vista Nature Center: A Banner Year for the Light-footed Clapper Rail Breeding Program

Clapper rail illustration
Light-footed Clapper Rail

The Chula Vista Nature Center continues the successful Light-footed Clapper Rail breeding program as these endangered birds lay an historic second set of eggs. While two of the three pairs of birds hatched eggs in early April, both pairs experienced some losses due to a cold spell because the chicks were young and unable to cope with the cold nights.

Fortunately both pairs laid a set of eggs in early May. This is the first time these birds have produced a second clutch in one season, which has important indications for the potential success of the breeding program.

The third pair of rails joined the two experienced breeding pairs, constructed a nest, and incubated a set of eggs. This is another historic first for the program since these two birds were captive-hatched and hand-reared as part of last year's breeding program. By mid-June the Center was home to three generations of the endangered Light-footed Clapper Rail.

Sea World's Bird Department has graciously agreed to incubate and hand-rear several of the eggs from the second clutches. The experiences and insights gained by hand-rearing efforts this year will help to better administer the program as it expands.

This year U.S. Fish and Wildlife funded a second "hack" enclosure. Hack enclosures are large habitats where young rails are housed, weaned off their prepared diets, and fed only live food prior to being released into the wild. This is a critical time for the birds as they refine their skills at finding and catching insects, crabs, and fish.

Like last year, Dick Zembal and Sue Hoffman will supervise and coordinate the release of this year's offspring into Southern California's coastal wetlands. Although there have not been any sightings of the birds released last year (an almost impossible task), the marsh in which they were released produced an unprecedented high number of Clapper Rail pairs when surveyed this spring.

It is exciting to be part of the team participating in efforts to restore such a critically endangered species like the Light-footed Clapper Rail. Everyone who supports our programs or volunteers at the Nature Center should be proud. The success of this program in the past two years speaks volumes about the dedication and ability of everyone at the Center.

--Charles Gailband and Barbara Moore, Chula Vista Nature Center


The Atlas Dodged the Bullet of Drought--but the Birds Didn't

Wrentit illustration
Wrentit

During the exceedingly dry spring of 2002, the Wrentit, Spotted Towhee, California Towhee, and Rufous-crowned Sparrow--four birds largely dependent on coastal sage scrub for breeding--experienced a nearly complete reproductive collapse. These four species are the foci of a multi-year study of the effects of habitat fragmentation that Doug Bolger and I are conducting through Dartmouth College, funded by the National Science Foundation. In 2001, when rainfall was near the long-term mean, my field assistants and I located 258 nests on our 16 research plots in and around Mission Trails Regional Park and the Otay-Sweetwater Unit of San Diego National Wildlife Refuge. About a quarter of these nests were of the Spotted Towhee and Rufous-crowned Sparrow, both of which place their nests on the ground and thus are notoriously difficult to find. By comparison, with comparable effort in 2002, the total number of nests found dropped by two orders of magnitude (see table below)! In comparison to 2001, the Wrentit and California Towhee, both of which place their nests in shrubs, fared especially poorly, perhaps owing to the lack of new growth and numerous dried leaves on most shrubs in their territories. Also, whereas many pairs of each of these four species attempted second or even third broods in 2001, the vast majority of birds did not even attempt to breed in 2002. We will be publishing complete details soon.

--Michael A. Patten

  2001 2002
Wrentit
Spotted Towhee
California Towhee
Rufous-crowned Sparrow
73
40
119
26
0
5
2
2

Nests located in 2001 and 2002 for four species that breed in coastal sage scrub. Data are courtesy an NSF-funded study through the Environmental Studies Program at Dartmouth College.

birdatlas@sdnhm.org

Summer 2002 Wrenderings | Wrenderings Archive | Bird Atlas Introduction