Loon at Portview Park
Wed, 4 Nov 1998 09:28:36 -0800 (PST)
From: Tom Condit
I saw my first loon of the season yesterday at Portview Park (bottom of 7th Street, Oakland). Unfortunately, I didn't have my binoculars with me, but it was either a Pacific or an Arctic judging by the general affect.
RE: Lake Merritt
Wed, 4 Nov 1998 10:10:44
From: Graham J Etherington
Larry mentions [on Nov 3] about the [Double-crested] Cormorants hanging around the islands. When I was there at dusk on Sunday, there were 'hundreds' of DCC's, using the island as a roost, most flying in from what I think is the north-west. The Horned Grebes were in the south-east (?) corner, where the river flows in, just along from the wooden raft.
Regards,
Graham Etherington
Changing Status of East Bay Birds
Wed, 4 Nov 1998 15:06:23 PST
From: Steve Glover
Hello East Bay Birders and Atlasers,
I was asked by Larry Tunstall to write something about birds now found in the East Bay that were formerly unknown. I'm not sure it is structured very well but what do you want for free? I welcome any comments, particularly criticisms, of the following. Even better, send comments to the entire group.
THE CHANGING STATUS OF THE BIRDS OF THE EAST BAY
About eight years ago now I began to do a research project about the birds of the East Bay, meaning the counties of Alameda and Contra Costa. In that time I have retrieved every observation I deemed interesting from The Condor (the journal of the Cooper Ornithilogical Soc[iety]), Field Notes (in all of it's various forms throughout the century), Directory to the Birdlife of the San Francisco Bay Region (Grinnell and Wythe 1929), The Distribution of the Birds of California (Grinnell and Miller 1944), and the newsletters of the three East Bay Audubon Chapters (The Quail of Mt. Diablo Audubon, The Kite Call of Ohlone Audubon, and, the oldest of all, The Gull of Golden Gate Audubon). The result is a binder three inches thick with over 13,000 observations.
Perusing old journals and newsletters is a classic two-headed monster, sometimes inspiring and enlightening, sometimes frustrating and even downright depressing. The first thing you must figure out are the limitations of old sightings in the context of what you are trying to learn. The foibles of past observors, at least from the perspective of the current era of field guides and identification articles, are downright comical. Other sightings, from observors still well known to this day, can generally be trusted with caution. In between is an immense gray area of species that are reasonable but often misidentified even today, of watchers long gone, and of things that could have been or might not have. Even more frustrating is the fact that newsletters, for some very good reasons, nearly always emphasize the unusual and the out- of-place. The end result glares from my three inch binder: A page and a half for Red-necked Grebe but only 3/4 of a page for Western/Clark's, four pages for Cattle Egret but only half a page for Snowy Egret... What this means is that these sources are better suited for some species than others.
In this case we are focusing on breeding species that have colonized the East Bay in recent times. By recent times I speak of just a little over a century since sightings appear in journals that are easily found. It turns out that for the thread we are trying to follow these sources actually work quite well, although not in every way. Species that we take for granted as we approach the end of the century were in many cases unknown at the beginning. Naturally a species that colonizes an area will be the focus of attention and this continues to this day. Great-tailed Grackles will most likely establish themselves, for better or worse, in the not-too-distant future. For now they are still rare enough that every sighting is carefully noted. Once their shrieks and screeches become commonplace at every sewage pond and cattle pen the number of reports will quickly diminish. This is exactly what happened with a number of species that now breed in varying degrees of commoness in the East Bay, some of them amongst our most familiar and conspicous species: Canada Goose, Chestnut-backed Chickadee, American Robin, Nothern Mockingbird, Brown-headed Cowbird, House Sparrow, and, of course, European Starling.
For most species that have colonized the East Bay in modern times it is a relatively straightforward process to pinpoint a specific period of time for colonization and at least make a good guess at where it happened first. What is more elusive, at least for some species, is explanations for these range expansions. What happened in the past 100 or so years that allowed these species to colonize the East Bay? Even more intriguing (although probably impossible to ever discover) is the possibility that some of these species may actually be re-colonizers. For all we have learned about bird distribution we are forced to confront the simple fact that our knowledge only extends back a mere 100 years, a mere blink of the eye in the overall scheme of things.
For each species we will note the times and places of sightings that establish the colonization of the species and, when applicable, discuss likely reasons this occurred. Some of these species are poorly established but nevertheless have begun to breed in certain situations.
Western and Clark's Grebes Western and Clark's Grebes are unknown as breeders in Contra Costa County [CCC] but in recent years have been found nesting in small numbers at the Alameda Creeks Quarries and San Antonio Reservoir in Alameda County [Ala]. It seems likely that breeding has probably gone unnoticed in the past and that they breed in years that conditions are suitable. It also seems apparent that nesting could not have taken place before the construction of reservoirs. Consistent water levels and the protection of shoreline vegetation at the watershed reservoirs would probably result in consistent breeding of both species.
Double-crested Cormorant A colony of Double-crested Cormorants was first discovered nesting on the Richmond-San Rafael [Bridge] in 1984 when five nests were found near the east end (American Birds 11/84). That same year 102 nests were found at the east end of the San Francisco Bay Bridge (American Birds 11/84). By 1988 there were 350-375 nests on the Bay Bridge and 275-300 nests on the Richmond-San Rafael Br. (American Birds Winter of 1988). This species was unknown as a breeder in the East Bay prior to these records. These manmade structures appear to have provided nest sites for a species already widely expanding it's range.
Pelagic Cormorant This species was first discovered as a breeder at West Brothers Island near Richmond, CCC, in 1995 when nine pairs nested. It is unknown whether or not these birds nested in 1996 or 1997 but they appear not to have bred in 1998. It remains to be seen whether or not this may have been due to El Niño conditions.
Canada Goose If this was a baseball record book then Canada Goose would almost surely have an asterisk attatched to it's name. The population of Canada Geese that breeds in the East Bay (and continues to spread rapidly) was introduced. Wing-tipped birds of the race moffitti were noted nesting at Lake Merritt, Ala, beginning in the early 1950s (source lost) and was said to have nested there "many years ago" (Gull #29, 9/47). An unrestrained pair was first noted breeding at Brooks Is., CCC, in 1959 (American Birds 10/59). They were noted breeding at the Bay Bridge Toll Plaza in 1961 (American Birds 10/61). They apparently first nested at Bay Farm Is., Ala., in 1967 (American Birds 10/73). They are now established throughout populated areas of the East Bay, especially golf courses, and appear to be spreading into East County.
Osprey Ospreys were unknown to Grinnell and Wythe (1929) except from the Russian River. Although they remain a rare breeder in the East Bay they have nested at Pt. Pinole Regional Shoreline and Briones Reservoir. They have clearly benefited from the construction of reservoirs (and planted food supply) and from buoys and channel markers (which they nest on). This species is commonly reported in newsletters but there were probably less than ten sightings before the early 1970s.
Red-shouldered Hawk The colonization of the East Bay by this species has been well documented. I can only find one record of this species from the 50s (and none before) and only four from the 60s. The records begin to increase rapidly in the mid-70s with the first nesting coming from Morgan Territory Rd., CCC, in 1979. They are now rather widespread in the East Bay, particularly in eucalyptus groves, and are even found in such situations in the lightly wooded eastern portion of east CCC. A 1973 journal article includes the East Bay in the primary range of the species and states that this range is little changed since the 1920s but this is clearly incorrect. ("The Red-shouldered Hawk in the Western United States", Sanford R. Wilbur, Western Birds, 1973, V. 4, pp. 15-22).
Ring-necked Pheasant This introduced species was said by Grinnell and Miller (1944) to be established only at Milpitas and San Jose. The Gull, however, lists sightings from the Lake Merritt area from 1932 and 1933 (Gull 14, 2/32, #2 and Gull 15, #2, 2/33). Since then they have spread throughout the East Bay, especially in East CCC where they continue to be released. Their future in the East Bay is less than secure, however. They are slowly disappearing from many sites, especially along the bay. This should hardly be surprising due to their preference for open grassland which is usually the first habitat to be built upon (just ask the Burrowing Owls).
Wild Turkey This is another introduced species whose origin is unquestioned. The first breeding evidence I can find is from Mines Rd. in 1986 (American Birds Fall of 1986). They are now found in wooded areas throughout southeastern Ala. Co and in recent years have colonized the slopes of Mt. Diablo, CCC. In 1998 they were found at Las Trampas Reg[ional] Park west of Danville, a portent of an almost certain spread through the watershed areas.
Black Oystercatcher This is one species that may have nested long before it was ever recorded as doing so. On the other hand it was unknown inside of San Francisco Bay by Grinnell and Wythe (1929) and I find no records from the East Bay until 1982 (American Birds 11/82). The first nest record came from Brooks Is. in 1984 (American Birds 11-12/1984. The habitat this species uses for nesting has gone unchanged through the century so the key may be the construction of breakwaters, a habitat they use frequently here. It may be that the few natural rocks in the bay were insufficient to support them.
American Avocet Grinnell and Wythe (1929) labeled this species as an irregularly common visitor, especially in the South Bay in fall and winter. I find no nest records until 1951 when they were found nesting at Bay Farm Island (American Birds 10/51). It seems that despite the first nest record coming from Bay Farm Is. the primary reason for their establishment was the construction of salt ponds in the South Bay.
California Gull California Gulls were known by Grinnell and Wythe (1929) as an abundant winter visitor with small numbers of non-breeders remaining through the summer. The first nests were not found until 1983 when there were nine nests at the Leslie Salt Ponds at Fremont (American Birds 11-12 1983). By 1985 there were 270 nests! (American Birds Fall of 1985). It doesn't seem like much of a stretch to say that it was the construction of salt ponds that allowed the gulls to colonize the area although one might wonder what took them so long.
Western Gull Grinnell and Wythe (1929) site nest colonies only from the coast. The first specific breeding record I find from inside the bay came from Red Rock Is., CCC, in 1952 (Gull 34, 9/52, 9) although the article mentions occasional nests on piles at the Bay Bridge. In 1967 forty pairs were found nesting on West Brothers Island, CCC (American Birds 10/67). They now nest commonly along the bay to as far east as West Pittsburg. It seems clear that this species benefited from the addition of pilings and channel markers and, when they were plentiful around the bay, from garbage dumps. The fact that they have continued to increase despite the closure of garbage dumps suggests that it is the lifestyle of humans that has allowed their increase.
Caspian Tern Caspian Terns are thought to have begun breeding in southern Alameda Co. as early as 1922 and were first confirmed in 1926. "They were reported as numerous in 1924" but not counted until 1926 when 164 nests were found ("History of a Nesting Colony of Caspian Terns on San Francisco Bay", Dudley S. DeGroot, Condor, V. 33, 9/31, 188-192). Note that Grinnell and Wythe (1929) report this location as San Mateo Co. Either way this was the only known colony in the Bay Region at that time. Since then large colonies have been established at the Alameda Naval Air Station and Brooks Is. near Richmond. Salt ponds may have been largely responsible for their colonization.
Least Tern The first record for the Bay Region was at Alameda 8/19/1923 (Grinnell and Wythe 1929) and there were but a handfull of records until the early 1950s when they began to accumulate rapidly. By the 1960s it was clear that they were breeding somewhere but were defying detection. It wasn't until 1967 that they were finally confirmed breeding in Alameda when three nests were found (American Birds 10/67). This number had grown to 108-114 pairs by 1990 (American Birds Wi. 1990). A few pairs also breed to the east at Pittsburg. It is unclear to me what allowed Least Terns to spread to the Bay Area but it may be the salt ponds in the South Bay since the breeding birds take their young there to forage and roost after fledging. It should also be noted that it has taken a lot of human intervention to protect the colony and allow numbers to increase. Fortunately the birds settled in areas somewhat protected from human disturbance.
Black Skimmer The first East Bay record came from Alvarado, Ala. Co., 7/20/78 when one was photographed (American Birds 11/78). Birds were noted sporadically in ensuing years, mostly in May. Nesting first occurred at Hayward Regional Shoreline, Ala. Co., in 1994. It is interesting that southbound birds have been noted with regularity at Moss Landing, Monterey Co. Were a few Skimmers nesting undetected somewhere in the bay before 1994? The range expansion of Black Skimmer in California seems tied to the construction of salt ponds at South San Diego Bay. The first record there was in 1971, the first nest record in 1976, so it doesn't seem surprising that our first record came in 1978 (The Birds of San Diego County, Phillip Unitt, 1984).
Rock Dove Colonization of the East Bay by Rock Doves apparently occurred before there were any observors in place to detect it. Nevertheless, they are present in developed areas throughout the East Bay.
Band-tailed Pigeon This species was unknown in summer in the East Bay by Grinnell and Miller (1929). The first detected nesting wasn't until 1960 when it was confirmed at Strawberry Canyon, Ala. Co. (Condor, 64:455). Today they are uncommon breeders in forested canyons of the Coast Ranges, east even into the moister canyons of the Diablo Range. It is interesting to speculate what allowed Band-tails to colonize the East Bay. As with many other species there was plenty of suitable habitat before 1960. Is this a case of a species that has re-colonized the area? Will it again withdraw in the future? Some species, such as Pygmy Nuthatch and Chestnut-backed Chickadee, are not highly migratory and are thus less likely to expand into a distant open nitch. Band- tails, on the other hand, are highly migratory. If plantings in the Berkeley Hills allowed them to colonize, as it may have done for it and several others, why didn't they colonize the rest of the East Bay earlier since there was already suitable habitat? It seems likely that many species invaded the East Bay from the south since that is the only direction in which there is an uninterrupted corridor of habitat. The East Bay is but a finger of woodland habitat, bordered on the west and north by water and on the east by the Central Valley, not at all a large area when you think about it. It wouldn't take much of a withdrawal for a species to recede from the East Bay. Has something happened on a larger scale to allow so many woodland species to invade in such a short period of time?
Belted Kingfisher Known to Grinnell and Miller (1929) only as a rare spring and fall migrant. The first nest record came from Arroyo Mocho in 1939 (Condor, date lost to me). Kingfishers currently breed locally in the East Bay, mostly in southern Ala. Co. and eastern CCC. It seems highly likely that this species bred in these unbirded areas previous to 1939. It must be stressed that little exploration was done away from a few selected areas around the bay, especially at Berkeley, Alameda, Hayward, and the South Bay. It is quite reasonable that local species such as kingfishers could be overlooked.
Lewis's Woodpecker This species was not detected breeding until 1914 at an area along Niles Canyon, Ala. Co. (Condor, 16, 7/14, p. 183). It seems highly likely that they had been breeding in southern Ala. Co. long before 1914 but went unrecorded because of a complete lack of exploration. Unfortunately they have again withdrawn, this time almost solely due to the spread of the aggressive European Starling.
Pileated Woodpecker One was apparently taken from Mt. Diablo prior to 1870 (Grinnell and Wythe) but one was not noted again until 1983. Since then birds have been sporadically noted from Mt. Diablo and, especially, from the area of Redwood Regional Park/Canyon. There was at least some coverage of Mt. Diablo and Redwood Canyon earlier in the century but it remains very possible that a tiny population defied detection.
Olive-sided Flycatcher Olive-sided Flycatchers were thought not to have nested in the East Bay until "altered by man." (Tracy Stores, "Range Extensions by the Western Robin in California", Condor V.28, 11/26, 264-267). According to Joseph Grinnell "the appearance in the past few years seems to correlate with growth of planted groves-as early as 1909". ("Second List of Birds of the Berkeley Campus", Condor V. 16, 1/14).
Common Raven Common Ravens were unknown to Belding or Grinnell and Wythe. The following charming account is the first record I can find for the East Bay: "Mr. Dyer asked for suggestions as to the identity of a large black bird with pointed wings which flew slowly and steadily across his view in Piedmont on November 21. The bird was high in the air and, soaring in a wide circle, it disappeared. It's call was "kruk, kruk." The several members who ventured opinions were inclined toward the Raven as the identity of Mr. Dyer's bird, a stranger in our region." (Condor 37, 3/35, p. 92) In 1976 pairs were seen in Berkeley and Hayward on 4/19 and 4/21. Because of their scarceness it was questioned whether or not they were the same pair! (American Birds 8/76) Common Ravens are now fairly common permanent residents and appear to be increasing rapidly. The nests thus far have invariably been on transmission towers.
Chestnut-backed Chickadee The range expansion of
Chestnut-backed Chickadee is far and away the most closely monitored and
documented case for the East Bay. Grinnell and Miller considered them vagrants
(as of 1944) to the East Bay District, recorded once at Berkeley and just
a few times at Hayward (p. 304). In 1938 a pair was seen nest-prospecting
at a creek near Sunol and in 1940 Henry W. Carriger took five fresh eggs
near Niles on 4/12. They apparently spread northwest, being found at Redwood
Regional Park in 1943. By spring of 1945 they were nesting at Wildcat Creek
in Tilden Park. Joe Marshall found a bird at U.C. Berkeley on 7/1/46 but
no evidence of nesting was found there until 1950 ("Some Ecological Relations
of Chickadees and Titmice in Central California", Keith L. Dixon,
Condor V. 56, 5-6/54, pp. 113-124). Citations since have documented
the expansion to Moraga, Mt. Diablo and Livermore. The expansion seems to
be complete with the birds in the more arid eastern regions such as Mt. Diablo
appearing to have a rather tenuous hold, often withdrawing in drier years.
It is clear that the source of the East Bay's chickadees
is from the south because they are of the race barlowi, the "Santa
Cruz Chestnut-backed Chickadee", rather than the "Marin Chestnut-backed
Chickadee" whose race is labeled neglectus.
Cohen (see Dixon above) stated in an 1895 report that they
breed "in the most unsettled portions of the county (Ala.)" So were chickadees
occupying the southeastern portions of Ala. Co. around Sunol for at least
half a century before spreading into the rest of the East Bay? Dixon discounts
this theory. He felt that "vegetational discontinuities" in the Santa Clara
Valley presented a barrier to eastward dispersal and that if birds had been
present in Sunol for at least fifty years, as contended, they would have
expanded much earlier. He felt that this barrier was bridged by the planting
of orchards and shade trees. The explanation seems plausible but we have
already noted several examples of species whose expansion came long after
the creation of the conditions that appear to have allowed their spread.
Red-breasted Nuthatch Red-breasted Nuthatches were unknown as nesters in the bay region in 1929 (Grinnell and Wythe, pp. 142-143). The first nesting was at Diamond Canyon, Ala. Co. in 1932 (Condor V. 34, 9/32, p. 234). Based on their current range here, primarily confined to redwood forest or stands of introduced Monterey Pines, it seems likely that exotic plantings allowed this species to colonize the East Bay. It could be that this species was formerly present in the redwood forests of the East Bay before wholesale logging but their absence from the humid coastal forests seems to rule this out.
Pygmy Nuthatch There were but two records of this species for the East Bay known to Grinnell and Miller, one from 1900 and one from August of 1935. It was thought that the 1935 bird (or possibly birds) was an immature. The first nest record came from Redwood Regional Park, CCC, in 1986 (American Birds fall of 1986). Pygmy Nuthatches in the East Bay are found almost exclusively in Monterey Pine stands in the western Berkeley Hills so there clearly was no suitable habitat before they were planted. Again we have to wonder what took them so long.
Brown Creeper Brown Creeper was first noted in the East Bay in 1890 by W.O. Emerson ("Notes From Haywards, California", Condor V. 2, 3/1900, p. 34). First noted nesting at U.C. Berkeley (Greek Theater) in 1918, and thought not to have nested there until the habitat was altered by man (Tracy Stores, "Range Extensions by the Western Robin in California", Condor V. 28, 11/26, 264-267). Again it appears that exotic plantings allowed this species to gain a foothold in the East Bay and they have since spread throughout the forests of the East Bay, even sparingly into the arid regions.
Winter Wren Winter Wrens were known to G&W and G&M as winter visitors to the East Bay. There were few citations to indicate even probable nesting until the late 1980s and the first documented nesting came in 1992 at Redwood Regional Park. They are still rather limited in distribution here, and always will be, but are very conspicuous during the breeding season and are not likely to have been overlooked by early observors.
American Robin Grinnell and Wythe list American Robins as nesting only as far south as Marin and Cazadero until 1917 when a nest was found at the Claremont Country Club (Amelia S. Allen, "Additional Notes of Birds of a Berkeley Hillside", Condor V. 45, 7-8/43, pp. 149-157). They appeared at U.C. Berkeley as nesters in 1920. Again it was landscape alterations credited (blamed?) for this colonization ("Range Extensions by the Western Robin in California", Tracy I. Storer, Condor V. 28, 11/26, pp. 264-267). They are now widespread breeders throughout the majority of the East Bay.
Northern Mockingbird It comes as a surprise to many to discover that Northern Mockingbirds, such a common sight in our yards, are but johnny-come-latelys to the East Bay. A Brief history of the Northern Mockingbird in the East Bay is as follows: They began nesting in Walnut Creek, CCC, in 1929. By 1934 there were at least 16 birds in the area. The first breeding at Hayward came in 1931, although winterers had been noted there since 1899. By 1935 there were also pairs present at Niles, Ala Co. (John A. Arnold, "The Changing Distribution of the Northern Mockingbird in California", Condor V. 37, 7/35, pp. 193-199). Other citations document nesting at Richmond by 1931 and in East Oakland in 1940. Arnold felt that arboreal plantings on a large scale in the Central Valley had furnished food and nest sites. The planting of ornamental shrubs in places like Walnut Creek helped them spread into the Bay Region. Arnold felt that when suitable agricultural conditions were combined with dry weather, such as from 1928-1930, the result was the spread of mockingbirds. The spread came from the south end of the Central Valley north, nesting north to Marysville by 1890, the exact opposite of other passerines we have looked at who have moved from cooler, moister situations to drier ones. It appears that the East Bay is just arid enough that they can be successful with the abundant food and nest sites.
European Starling The first European Starling did not reach California (at Tule Lake) until 1942. The first East Bay record was from Pt. Isabel, Richmond, in 1950. I don't have the first nesting but it was probably late in the 1950s. Since then they have spread throughout the entire East Bay and become our most common species by a wide margin.
Western Tanager Grinnell and Wythe knew of breeding only from Sonoma Co. The first nest record I found is a probable record from 1924 and a confirmation from 1930 near Moraga. It is possible that this species went overlooked but it seems unlikely.
Dark-eyed Junco Known to Belding as a winter visitor, the first known nest record for the East Bay wasn't until 1917 when partly-feathered young were found at the Claremont Country Club (A.A. Allen, "Western Robin and Sierra Junco Nesting in Alameda Co., California" Condor V. 19, 11/17, p. 185). A pair had been seen on campus as early as 1912, without any signs of breeding. by J. Grinnell who speculated that "sooner or later, as planted groves become denser and taller, a colony will establish itself, as at Stanford." ("Second List of Birds of the Berkeley Campus", Condor V. 16, 1/14). They did and have since spread throughout the woodlands of the East Bay.
Brown-headed Cowbird The story of the spread of Brown-headed Cowbirds throughout the west in the 20th century is well documented, particularly in the East Bay. The invasion apparently began at the Colorado River in about 1900, reaching the Bay Region by 1922! The first record is believed to be the discovery of ten eggs in nests in Irvington (Fremont) in 1922. The fact that they apparently spread both north and south from Irvington over the next ten years indicates that this original population may have been a disjunct one. They were not noted at Berkeley until 1934. The reasons for the spread are several. The creation of preferred foraging areas, namely areas of short grass or bare ground amongst large grazing animals, allowed them to forage away from breeding areas. High fecundity of females (30-40 eggs per season) provided enormous growth potential. Finally, the pathway provided by man allowed this parasitic species to come into contact with host populations not previously sympatric with any specie of brood parasite. (Stephen I. Rothstein, "The Cowbird's Invasion of the Far West: History, Causes and Consequences Experienced by Host Species" from A Century of Avifaunal Change in Western North America, edited by Jehl and Johnson, 1994, Cooper Ornithilogical Soc.).
Hooded Oriole Hooded Orioles apparently did not reach the Bay Region until after 1930. The first nesting appears to have been at Wildcat Canyon in 1937 (G&W, p. 431). By the early 1950s they were well established along the bay plain. I have no information on the statewide spread of this species but it is clear that the most important factor is the planting of washingtonia palms since there appear to be no nest records from the East Bay away from this species.
House Sparrow This species was already abundant in populated areas of the East Bay by the end of the 1880s (L. Belding, 1890, "Land Birds of the Pacific District", Occasional Papers of the California Academy of Sciences, 2:1-174).
Steve Glover
11/4/98