DISCUSSION
Hurricane Rosa: 1–2 October 2018
Veteran East Coast hurricane chaser Marshall J. Iliff kindly prepared the following account of his Rosa chase with Erickson. Like previous efforts following hurricanes in BCS, this one met with only limited success.
====
In the past two decades, several tropical systems (e.g., John 2006, Odile 2014) have impacted BCS, but Rosa 2018 was the first to make landfall in BC since Nora 1997. Rosa began as a tropical depression 22 Sep and became a hurricane 26 Sep. She rapidly intensified to a Category 3 storm 28 Sep before dropping steadily in intensity and moving north northeast to BC. Her core structure rapidly eroded, and by 1 Oct she had weakened to a tropical storm; by landfall early on 2 Oct she had further weakened to a tropical depression and moved rapidly across the mid-portion of the peninsula, reaching Arizona 3 Oct. Unlike East Coast storms, it is the s. side of Pacific hurricanes that bring the strongest onshore winds when arriving from the west, changing the strategy for those seeking displaced seabirds. The peninsula has few permanent water bodies where seabirds might fall out, but displacement of seabirds across the peninsula to the Gulf of California does seem likely to occur in such storms.
With the above in mind (and with a healthy dose of caution), we worked the Mexicali Valley (focusing on water bodies) in the morning of 1 Oct, as the outer bands of Rosa brought high clouds and occasional very light drizzle. We headed to San Felipe in the afternoon before the heaviest rain arrived, settling in for checks of the waterfront and careful seawatches from Punta Estrella in driving rain and 15–20 mph ne. winds. The seabird show was active but unremarkable, with elevated numbers of Black Terns (e.g., 67 at Punta Estrella and 105 at San Felipe harbor) and Common Terns (23 at Punta Estrella and 20 at San Felipe harbor), and a few unusually late juvenile Least Terns (4–7 in the Punta Estrella area, ph. MJI; first Oct BC record) being the most notable observations, though these were likely displaced and concentrated within the Gulf of California rather than transported overland. By the following morning these birds were gone, and no unusual seabird species or numbers were noted.
Perhaps the most interesting story from the storm involved swifts, with a 1 Oct total of 42 Vaux’s Swifts from six locations between Mexicali and San Felipe and six more at four locations the following day. More notable was a single Black Swift (with only two prior BC reports this century and no prior records from the Mexicali Valley) flying with Vaux’s Swifts over the Las Arenitas sewage ponds; it was seen well but just out of photo range. Vaux’s Swift fall migration slices across n. BC (the species becomes rare quickly in the southern three quarters of the peninsula) and peaks in early October, with most detected in the cooler climates of nw. BC. They are presumably easily missed as they migrate high overhead on the less-well-covered e. side of the state. In the same Sep–Oct window Black Swift is rare in s. California, where desert records are especially few; even on the Pacific side they are famous for needing inclement weather to bring them down low enough for observation.
Given the challenges of combining favorable winds, a safe and dry vantage, and areas likely to concentrate seabirds, the ideal conditions would likely be a storm that tracks northward up the Gulf of California—or potentially crosses farther south and strengthens again in the Gulf. A storm-watcher who encounters north or northeast winds on the famously productive leading edge of a storm could strike the jackpot but would need to be at a safe, sheltered site or surveying a fairly weak and non-threatening storm. (Remember that more southerly storms coming off warmer water are sure to be more powerful!) The smarter play might be savvy positioning after the storm’s passage, which could intersect birds reorienting back to the south, especially at sites like Punta Arena (near La Ribera, BCS), which has a solid track record for Gulf seawatches. Since many storms do follow similar paths, these strategies could be kept in mind for would-be hurricane chasers in the future, but they did not apply well to Rosa. Birdcast provided real-time predictions in advance of Rosa (albeit based on models predicting a much stronger storm at landfall), an archive of the storm track and bird records, and historical context of records from other Pacific tropical systems (tinyurl.com/HurricaneRosa2018); be sure to watch Birdcast in any future storms.
A closing note of caution for future storm chasers: multiple road washouts prevented travel along Mexico Route 5 south of San Felipe, and we carefully avoided the heaviest rain and any areas that might strand us or endanger us. Storm chasers in the desert should consider worst-case scenarios for flash floods, including road and bridge washouts. As always, the first concern should be to exercise extreme caution.
=====
Pacific Island Birds
Observations from islands off the Pacific coast of the peninsula were often highlighted in NAB reports, before and after Erickson et al. (2010) presented species lists and limited annotations for all but the most southerly islands. Nesting seabirds, like the nearly endemic Black-vented Shearwater, have rightly received the most attention from researchers, such as those affiliated with Grupo de Ecología y Conservación de Islas, A.C. (GECI). Conservation and restoration of islands following the ravages of non-native invasive species are most important. Nevertheless, use of the islands by migratory birds and (re)colonization of the islands by landbirds are of great interest as well. Table 1 lists highlights of this sort from the reporting period. An update of island species lists in collaboration with GECI is anticipated.
The most remote, infrequently visited, and difficult to access of the region’s Pacific islands are Rocas Alijos, and we treasure all reports from there. Lately, Robert McNab has been the fisherman/birder to visit most frequently, having made August observations in at least 2012, 2014, 2017, and 2018. The only papers to specifically address the birds of this area are those by Pitman (1985), Everett and Pitman (1996), and Senf and Wicksten (1996).
Baja California Sur Gulf Island Landbirds
In 2018, Marrón participated in an expedition to most of the main Gulf islands of BCS aboard the vessel Searcher. The trip was organized by Sula Vanderplank in collaboration with the San Diego Natural History Museum and the University of California Institute for Mexico and the United States. From 9–20 Nov 2018, 14 islands were visited, from Tortuga in the north to Cerralvo in the south. While other biologists concentrated on other organisms, Marrón was primarily responsible for landbirds. Fifty-seven terrestrial species were observed. Based on a review of eBird records, the NAB database (cf. Erickson et al. 2008), Banks (1963), Cody and Velarde (2002), Lobera Álvarez (2007), and Sarabia Trejo (2008, 2015), 42 new island records were established (see lists below). Some of the islands are very small and appear to have no previous ornithological record of terrestrial species, such as Galeras, San Diego, and San Cosme. Tortuga appears to have been visited infrequently and provided many new records. It is far from shore and has many snakes. San Marcos is close to the peninsula and has a resident human community, two features responsible in part for the high number of new records there. Rock Pigeon and Eurasian Collared-Dove appear to have been recorded only once before on any of these islands. The Gulf islands have been relatively well studied in terms of reptiles, mammals, and seabirds, but we call again for a systematic survey of all the Gulf islands in order to target nesting landbirds.
New Records for BCS Gulf Islands
Carmen: Zone-tailed Hawk
Catalina: House Wren
Cerralvo: Gilded Flicker
Galera Este: “Large-billed” Savannah Sparrow
Galera Oeste: Peregrine Falcon, “Large-billed” Savannah Sparrow
San Cosme: Turkey Vulture, Ladder-backed Woodpecker, Common Raven, Verdin, Rock Wren, Black-throated Sparrow
San Diego: Costa’s Hummingbird, Turkey Vulture, Red-tailed Hawk, Verdin, Northern Mockingbird
San Francisco: Cooper’s Hawk, Zone-tailed Hawk
San José: Cooper’s Hawk, Northern Rough-winged Swallow, Black-throated Gray Warbler
San Marcial: Savannah Sparrow (P. s. sandwichensis group)
San Marcos: California Quail, Black Phoebe, House Wren, Blue-gray Gnatcatcher, Clay-colored Sparrow, Savannah Sparrow (P. s. sandwichensis group), Hooded Oriole, “Audubon’s Warbler”, Western Tanager, Rock Pigeon, Eurasian Collared-Dove
Santa Cruz: Barn Owl, Gila Woodpecker
Tortuga: White-winged Dove, Northern Harrier, Burrowing Owl, Clay-colored Sparrow, “Gambel’s” White-crowned Sparrow, Green-tailed Towhee
Baja California Mountain Birds
Limited and irregular coverage of BC’s mountains in the 20th century, due to access and other issues, does not allow us to make statements with confidence about potential changes in bird populations there. Coverage still is far from consistent. A number of nesting species were not discovered until late in the century (Kratter 1991, Erickson et al. 1994, Erickson and Wurster 1998), and additional discoveries are yet to come. Clark’s Nutcracker and Red Crossbill were believed to be resident in the mountains 100 years ago (Grinnell 1928) but may always have been of irregular occurrence. That certainly now appears to be the case for the nutcracker (Erickson et al. 2001) and the crossbill probably as well. We are aware of no confirmed nesting by the nutcracker and none by the crossbill since the 1920s (Huey 1927, 1928), and before then only from the Sierra Juárez. This period Clark’s Nutcracker was found in the Sierra San Pedro Mártir with at least three seen 16 Apr–20 May 2019 (ph. KTTC, aud. JTS et al.). Red Crossbill was unrecorded in 2016 and 2018, a few were found in the Sierra San Pedro Mártir in 2017, and more were reported in 2019 than in any year in decades: in the Sierra San Pedro Mártir and the Sierra Juárez. More information needed!
Updated Baja California and Baja California Sur Checklists
Included here is an update of checklists prepared previously by Howell et al. (2001) and Erickson et al. (2013). Included are 529 naturally-occurring species, 480 for BC and 449 for BCS. Confirmed and probable native nesting species total 240 (12 only historically): 222 for BC (14 only historically) and 149 for BCS. BCS has outpaced BC in the accumulation of new species since the last checklist (15 to 4, excluding taxonomic splits). The quality of documentation continues to improve, but 20 species in the region still lack confirmation by specimen, photograph, audio recording, or sonogram. Another 16 species are so undocumented in one state or the other.
Taxonomic Issues. Since the last checklist edition, new taxonomic problems have arisen for us as eBird reviewers and chroniclers of the state lists. Foremost among these is recognition of three storm-petrel species whereas once there had been only one, Leach’s Storm-Petrel (Ainley 1980, Chesser et al. 2016). All three nest in our region, but Townsend’s Storm-Petrel (summer breeder) and Ainley’s Storm-Petrel (winter breeder) are endemic to I. Guadalupe, whereas Leach’s Storm-Petrel is still recognized as circumpolar. Field identification of these three is highly problematic, as all show varying degrees of white on the uppertail coverts but in different proportions of their populations. Following the most widely accepted classification, nominate Leach’s Storm-Petrel (O. l. leucorhous) is widespread in the northern hemisphere, nesting south to s. California; it is abundant in the region, primarily outside the breeding season. “Chapman’s Storm-Petrel” (O. l. chapmani) nests at Is. Coronado, Is. San Benito, and probably Rocas Alijos. The population at San Benito has been estimated at 1.2 million birds (Wolf et al. 2006), so “Chapman’s” must account for a large proportion of storm-petrels seen in the region. In contrast, Townsend’s Storm-Petrels and Ainley’s Storm-Petrels probably number no more than a few thousand birds each. Using identification strategies developed in California (Howell et al. 2009, Howell 2012, Howell and Zufelt 2019), we recognize Townsend’s Storm-Petrel as having occurred in BCS waters (Figure 45). Reports of the rarer Ainley’s Storm-Petrel at sea will be extremely difficult to evaluate, and any further elucidation of the at-sea distribution of these taxa in our waters will surely be slow to come.
“Sage Sparrow” now comprises Sagebrush Sparrow and Bell’s Sparrow (Chesser et al. 2013). These species overlap broadly in appearance, particularly the two subspecies that winter in the Colorado Desert portion of BC: canescens (Bell’s) and nevadensis (Sagebrush). Patten and Unitt (2002) went so far as synonymizing the two. The specimen record is weak in our area: Grinnell (1928) reported six canescens and three nevadensis taken at Cañada Cantu de las Palmas near Laguna Salada in 1927, and the only subsequent specimen is a nevadensis from Calamajué 1 Feb 1931 (MVZ 170005). Based on his collecting just across the California border, van Rossem (1911) reported these sparrows as abundant in the Salton Sink, with canescens present in “slightly larger numbers.” The incorrect mapping of these species by Sibley (2014), showing only Sagebrush Sparrow in ne. BC, has not helped our cause.
Splits in the genus Aphelocoma have continued, with Woodhouse’s Scrub-Jay (A. woodhouseii) recognized by Chesser et al. (2016). This interior species is unrecorded in our region, but winter strays have been found as close as Winterhaven, Arizona and Brawley, California, suggesting it is only a matter of time before the species is recorded in ne. BC. Also unconfirmed in our area is Cordilleran Flycatcher (Empidonax occidentalis), which may occur in our area occasionally but presents an exceedingly difficult identification challenge. The most recent taxonomic revision is recognition of Mexican Duck (Anas diazi) as a species separate from Mallard. We eagerly await the first regional record, which will presumably come from the Mexicali Valley.
Taxa and Populations Unrecorded Since 1999. Table 3 lists 49 species, subspecies, and populations not observed in BC or BCS, or both, since 1999. Eleven island losses are the most critical, as eight of those represent entire taxa extinctions. These include six from Guadalupe and one from San Benito, but the validity of the “Todos Santos” Rufous-crowned Sparrow (A. r. sanctorum) has been questioned. Many of these losses were discussed in more detail by Greenway (1967).
Most of the other unrecorded entities (23) are of northern origin, i.e, North America north of Mexico. Eight are of Mexican origin, four are Asian (vagrants), and three are oceanic. In the face of ongoing climate change, these numbers are intuitive and also in keeping with the findings of Erickson et al. (2018), who found the great majority of latitudinal range changes in birds in BC, BCS, and California over the last 100 years to be in a northward direction. They also found the majority of northward contractions in BC and s. California, rather than BCS and n. California. This too matches our findings of 17 northern losses in BC (excluding islands) and only eight in BCS. Overall, BCS fared much better than BC in the loss department, with only 12 losses compared to 39 for BC. BC has lost 13 nesting populations compared to none for BCS.
Table 1 Firsts and other selected records for Pacific islands.
|
Species |
Island |
Dates |
Observers |
Notes |
|
Greater White-fronted Goose |
Cedros |
12 Jan 2019 |
ph. DRh |
first |
|
“Aleutian” Cackling Goose |
s. of Guadalupe |
19 Oct 2017 |
ph. JP |
first |
|
Lesser Scaup |
San Roque |
11 Feb 2017 |
AEM, JM |
first |
|
Red-breasted Merganser (2) |
San Roque |
11 Feb 2017 |
AEM, JM |
first |
|
Eared Grebe |
San Roque |
11 Feb 2017 |
AEM, JM |
first |
|
Lesser Nighthawk |
Natividad |
13 Jun 2018 |
JEAS |
first |
|
Black-necked Stilt (5) |
Todos Santos Sur |
29 Mar 2017 |
GECI |
first |
|
Killdeer |
Guadalupe |
10 Sep 2018 |
RH |
first since 1989 |
|
Glaucous-winged Gull |
San Roque |
11 Feb 2017 |
ph. AEM, JM |
first |
|
Common Loon |
Guadalupe |
14 Nov 2018 |
CC, ph. NPa |
first |
|
Masked Booby |
Natividad |
13 Jun 2018 |
JEAS |
first |
|
Nazca Booby |
w. of Natividad |
23 Nov 2017 |
ph. HM |
first |
|
Brown Booby (180) |
Coronado |
23 Jun 2019 |
RV et al. |
high count |
|
Brown Booby (57) |
Guadalupe |
2 Oct 2017 |
JP |
high count |
|
Red-footed Booby |
Guadalupe |
7–8 Aug 2017 |
DWP |
first |
|
Red-footed Booby |
vic. Guadalupe |
5 Aug 2018 |
DWP |
|
|
Red-footed Booby |
vic. San Jerónimo |
9 Aug 2017 |
DWP |
first |
|
Red-footed Booby (4) |
vic. San Jerónimo |
9 Aug 2018 |
DWP |
|
|
Red-footed Booby |
Rocas Alijos |
6 Aug 2018 |
†RBM |
first |
|
Black-crowned Night-Heron |
Todos Santos |
17 May 2017 |
CF et al. |
first for any Pacific island |
|
Rock Wren |
San Roque |
11 Feb 2017 |
AEM, JM |
first |
|
House Finch |
San Martín |
13 May 2018 |
GMa et al. |
first |
|
“Oregon Junco” |
Natividad |
2 Nov 2018 |
ph. SNGH et al. |
first |
|
“Large-billed” Savannah Sparrow |
San Roque |
11 Feb 2017 |
ph. AEM, JM |
first |
|
Tennessee Warbler |
Natividad |
26 Oct 2017 2 Nov 2018 |
RAH, ph. SNGH et al. |
first |
|
American Redstart |
Natividad |
11 Oct 2016 |
ph. RAH et al. |
first |
|
Black-throated Gray Warbler |
Todos Santos |
22 Apr 2017 |
GECI |
first |
|
Western Tanager |
San Martín |
13 May 2018 |
GMa et al. |
first |
Table 2 Annual occurrence of selected vagrant passerines in fall, with individuals from BC and BCS shown on either side of the slash. An asterisk indicates records discussed specifically in the text.
|
Species |
2016 |
2017 |
2018 |
2019 |
Average, 2006–2015 |
|
Great Crested Flycatcher |
0 |
||||
|
Eastern Kingbird |
1*/ |
1*/ |
0.2 |
||
|
Yellow-bellied Flycatcher |
0.1 |
||||
|
Least Flycatcher |
/1 |
1.6 |
|||
|
White-eyed Vireo |
0 |
||||
|
Yellow-throated Vireo |
0 |
||||
|
Blue-headed Vireo |
0.1 |
||||
|
Philadelphia Vireo |
1/ |
0.3 |
|||
|
Red-eyed Vireo |
1/ |
2/1 |
0.9 |
||
|
Yellow-green Vireo |
2/ |
2/ |
2/ |
1.4 |
|
|
eastern thrushes |
0 |
||||
|
Gray Catbird |
1/ |
1/ |
1/ |
1/ |
0.7 |
|
Brown Thrasher |
0.1 |
||||
|
Bobolink |
8/ |
2/ |
3/ |
/1 |
4.0 |
|
Orchard Oriole |
1/ |
2/ |
3/1 |
2.7 |
|
|
Baltimore Oriole |
/2 |
2/1 |
2.6 |
||
|
Ovenbird |
1/ |
1.3 |
|||
|
Worm-eating Warbler |
0 |
||||
|
Louisiana Waterthrush |
0.1 |
||||
|
Golden-winged Warbler |
0 |
||||
|
Blue-winged Warbler |
0.2 |
||||
|
Prothonotary Warbler |
/1 |
1/ |
3/ |
0.6 |
|
|
Tennessee Warbler |
2/2 |
2/1 |
4/2 |
4/ |
5.3 |
|
Lucy’s Warbler |
1/ |
1/1 |
1/ |
2/ |
3.6 |
|
Virginia’s Warbler |
/1 |
2/ |
2/ |
0.8 |
|
|
Connecticut Warbler |
0 |
||||
|
Mourning Warbler |
0.3 |
||||
|
Kentucky Warbler |
0.1 |
||||
|
Hooded Warbler |
1/ |
1.2 |
|||
|
Cape May Warbler |
1/ |
1/2 |
0.4 |
||
|
Cerulean Warbler |
0 |
||||
|
Northern Parula |
4/ |
1/ |
1/ |
2/ |
1.6 |
|
Magnolia Warbler |
1/ |
2/ |
0.7 |
||
|
Bay-breasted Warbler |
/1* |
0.2 |
|||
|
Blackburnian Warbler |
2/ |
3/ |
2/ |
1.6 |
|
|
Chestnut-sided Warbler |
1/1 |
2/ |
2/ |
3/1 |
1.4 |
|
Blackpoll Warbler |
3/ |
4/ |
1/ |
4/ |
6.5 |
|
Black-throated Blue Warbler |
1/ |
2/ |
1.6 |
||
|
Palm Warbler |
4/ |
3/1 |
4/ |
3/ |
4.7 |
|
Pine Warbler |
/1* |
1*/ |
0.3 |
||
|
Yellow-throated Warbler |
1/ |
0.5 |
|||
|
Prairie Warbler |
1/ |
0.9 |
|||
|
Grace’s Warbler |
1*/ |
0.3 |
|||
|
Black-throated Green Warbler |
0.5 |
||||
|
Canada Warbler |
1/ |
2/ |
0.7 |
||
|
Painted Redstart |
0.2 |
||||
|
Hepatic Tanager |
0.4 |
||||
|
Scarlet Tanager |
/2 |
1/ |
2.7 |
||
|
Rose-breasted Grosbeak |
4/ |
2/ |
2/1 |
2.7 |
|
|
Indigo Bunting |
/1 |
1/ |
1/ |
2.3 |
|
|
Painted Bunting |
1/ |
1/ |
0.7 |
||
|
Dickcissel |
2/ |
9/1 |
3.6 |
Table 3 Year last recorded for taxa and other populations not found since 1999. A double XX indicates the taxon or population has been recorded in that state since 1999.
|
1800s |
1900–1989 |
1990s |
||||
|
Taxa or Population |
BC |
BCS |
BC |
BCS |
BC |
BCS |
|
Fulvous Whistling-Duck |
1958 |
XX |
||||
|
Tundra Swan |
1990s |
XX |
||||
|
Sora, suspected nesting |
1928 |
1997 |
||||
|
Mountain Plover |
XX |
1925 |
||||
|
Crested Auklet |
1980 |
|||||
|
Red-tailed Tropicbird |
1887 |
|||||
|
Arctic Loon |
1998 |
|||||
|
Short-tailed Albatross |
XX |
1888 |
||||
|
Wedge-rumped Storm-Petrel |
1950 |
XX |
||||
|
Guadalupe Storm-Petrel |
1912 |
|||||
|
American Bittern, suspected nesting |
1893 |
|||||
|
Roseate Spoonbill |
1915 |
XX |
||||
|
Sharp-shinned Hawk, summer |
1977 |
|||||
|
Bald Eagle, nesting |
1924 |
XX |
||||
|
Rough-legged Hawk |
1962 |
|||||
|
Elf Owl |
1947 |
XX |
||||
|
Spotted Owl |
1972 |
|||||
|
“Guadalupe” Northern Flicker |
1906 |
|||||
|
Crested Caracara, nesting |
1926 |
XX |
||||
|
Guadalupe Caracara |
1900 |
|||||
|
Great Kiskadee |
1987 |
|||||
|
Thick-billed Kingbird |
1995 |
XX |
||||
|
Alder Flycatcher |
1911 |
|||||
|
Willow Flycatcher, nesting |
1925 |
|||||
|
Steller’s Jay |
1885 |
|||||
|
Clark’s Nutcracker |
XX |
1996 |
||||
|
Red-breasted Nuthatch (I. Guadalupe) |
1971 |
|||||
|
“Guadalupe” Bewick’s Wren |
1892 |
|||||
|
“Guadalupe” Ruby-crowned Kinglet |
1953 |
|||||
|
Dusky Warbler |
1995 |
|||||
|
Arctic/Kamchatka Leaf Warbler |
1991 |
|||||
|
Eastern Yellow Wagtail |
1997 |
|||||
|
American Pipit, suspected nesting |
1991 |
|||||
|
“San Benito” House Finch |
1938 |
|||||
|
Purple Finch, suspected nesting |
1924 |
|||||
|
Red Crossbill (I. Guadalupe) |
1897 |
|||||
|
Lapland Longspur |
XX |
1997 |
||||
|
Harris’s Sparrow |
1995 |
|||||
|
“Channel Islands” Song Sparrow |
1977 |
|||||
|
“Todos Santos” Rufous-crowned Sparrow |
1938 |
|||||
|
“Guadalupe” Spotted Towhee |
1897 |
|||||
|
Louisiana Waterthrush |
1996 |
XX |
||||
|
Golden-winged Warbler |
1991 |
1996 |
||||
|
Lucy’s Warbler, probable nesting |
1928 |
|||||
|
Connecticut Warbler |
XX |
1999 |
||||
|
Kentucky Warbler |
XX |
1999 |
||||
|
Fan-tailed Warbler |
1925 |
|||||
|
Red-faced Warbler |
1985 |
|||||
|
Summer Tanager, nesting |
1928 |
|||||
|
Totals |
6 |
1 |
23 |
5 |
10 |
6 |
Next page: Acknowledgements and Literature Cited –>
