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Snowy Plovers of Malibu Lagoon – The Middle

May 19, 2017

Click HERE for a slideshow of banded Snowy Plovers, then scroll down
to the slideshow located below the photo of the banded chick.
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We continue with our reprint of this August, 2012 series to reacquaint
our readers with the local history of these birds.
For the first time in over
seventy years,

Snowy Plovers have again nested on Los Angeles County beaches.

Part III – Nesting and Wintering
Western Snowy Plovers (WSPs) are colonial nesters, up to 246 birds nesting in close proximity. Each nest is a bare scrape in beach sand, occasionally adorned with debris, twigs and pebbles. It might, but need not, have sparse vegetation nearby. The male often makes 1-2 false scrapes nearby. Three (occasionally two) eggs are laid, buff with black marks.  Both parents incubate the eggs for 27-28 days. Hatchlings are precocial –the relatively long incubation period allows them to be born downy, mobile, ready to follow their parents and find their own food.  In about a month they’re full size and able to fly.

Of the estimated 50 California nesting sites used in 1970, about half are used today. In 1949, the last active nest of a Snowy Plover on L.A. County beaches was reported at Manhattan Beach. There have been no documented cases of a Snowy Plover nesting within the county since then, although no systematic survey of suitable county beaches was done between 1970 and the mid 2000s. Kiff & Nakamura (1978) held that they “probably nested at Malibu Lagoon until the 1960s when increased human use of the area displaced the birds,” but provided no supporting evidence.

Snowy Plover in its sandy hollow home on Surfrider Beach (C. Bragg 9/25/11)

As part of the ongoing PRBO study, nestlings are banded each year. Each location/year has a unique band pattern. Currently, 13 colors are used on four bands, two per leg. GG:AR means: bird’s left leg Green above Green, bird’s right leg Aqua above Red. This particular pattern was found winter of 2011 in the Surfrider flock; the bird was one of three banded in Summer 2011 at Oceano Dunes near Pismo Beach.

As the result of the first Winter Window Census in January, 2001, we found that WSPs in Los Angeles County were concentrated into seven locations which were their winter roosting sites; outside those locations they were extremely uncommon. We found:

Location Jan ’01 Jan ‘04
Zuma Beach north 106 130
Surfrider Beach 2 33
Santa Monica north 14 32
N. Dockweiler/MDR 16 12
S. Dockweiler 18 13
Hermosa Beach 23 38
Cabrillo Beach 0 7
Other Areas 0 0
Totals 179 265

Birds in 2001 at Surfrider (2) and Cabrillo (0), although seen in good numbers the previous day, were low on count day due to poor weather conditions (storm surge combined with high tide of the year).

To my knowledge, no one knew that Snowies stayed so close to their winter roosts. All later censuses proved that 2001 was not an anomaly. With few exceptions, the birds are just not found more than a few hundred yards – usually much less than that – from their roosting sites. Their seven roosting sites, with one exception, have not changed since then. The exception was on Dockweiler, where the roost at the foot of the hang-gliding slope disappeared when a site about ¼ mile north appeared.

Beach groomer operators on Zuma can’t see the Snowies while they remove the wrack, their food source – a double whammy! (A. Albaisa 3/16/09)

Part IV – Population Fluctuations
As described previously, Western Snowy Plovers (WSP) wintering on Pacific beaches are extremely faithful to their roosting sites and are rarely seen outside their immediate vicinity, rarely more than a hundred yards down the beach. Northern Zuma Beach consistently has [Ed. – declined since 2012] the largest wintering flock of  WSPs, averaging 46% of total county birds, followed by Surfrider and Santa Monica Beaches with 14% each.

Snowy Plover juvenile tooling down Surfrider Beach
(C. Almdale 10/24/09)

By recording bands, we discovered that there is some back-and-forth movement between Zuma, Surfrider and Santa Monica flocks. Of L.A. County’s approximately 75 miles of beach, Snowies confine themselves almost entirely to less than 1 mile, and closer to 800 yards,  0.6% of the total linear beachfront. Ryan Ecological Consulting (Feb. 2010 & Nov. 2010) suggested that conservation efforts be focused on these areas, an opinion with which I heartily concur.

California’s population of WSPs fluctuates significantly seasonally and yearly:

Year Summer Census
Winter Census
Increase in Birds LA County Winter Census
Surfrider Census
2005 1680 4261 2581 334 12
2006 1719 3546 1827 196 34
2007 1362 3290 1928 200 37
2008 1394 3205 1811 233 36
2009 1405 3379 1974 244 37
2010 1591 3744 2153 211 47
2011 1715 3763 2048 326 78
Avg. 1552 3598 2046 249 40

Summer Census: Adult WSPs counted on the California breeding grounds.
Winter Census: Total Calif. birds found during the following January’s Winter Window Census.
Increase in Birds: Winter population minus Summer population of Snowy Plovers. The increase consists primarily of young WSPs fledged that summer on the coast, plus a few inland race Snowy Plovers spending winter on California beaches. Some Washington and Oregon WSPs winter in California (CA). Most CA WSPs winter in CA, a few winter out-of-state (Baja California).  As more migrate into CA for the winter than migrate out, this net increase is included in the “Increase in Birds” numbers.
LA County Winter Census: Total birds counted in L.A. County on the Winter Window Census.
Surfrider Census: Total birds at Surfrider Beach on the Winter Window Census.

From this information, we can easily draw these conclusions:

  • 2006-07 Winter population declined 17% from the prior winter
  • 2007 breeding population declined 21% from the prior summer
  • 2007-08 Winter population declined 7% from the prior winter
  • 2008-09 Winter population declined 2.6% from prior winter
  • 2011 breeding population has rebounded to its 2006 level
  • 2011-12 Winter populations are still down 12% from 2005

No solid reason was ever determined for the declines. Some researchers think a Winter cold snap might have caused the initial decline in 2006-07; other researchers disagree, saying they’d already seen a decline in returning birds in Fall, 2006.

The Los Angeles County wintering population fluctuates between about 200-330 birds, averaging about 7% of the total California Snowy Plover Winter population. For the sake of comparison, this is about 2% of Malibu’s 2010 human population of 12,645.

Checking the plover virtual enclosure, Surfrider Beach (L. Johnson 5/27/12)

The highest count ever recorded for Surfrider Beach (Malibu Lagoon) was 81 birds on Jan. 22, 2012.  This count included one banded bird GG:AR (previously mentioned), first appearing at Surfrider on Sep. 25, 2011 and reappearing on Christmas Day, Dec. 25, 2011. Upward trends are heartening to see, but unexpected downturns can always reoccur.

Part V – Back to Surfrider Beach
Western Snowy Plovers (WSPs) do not nest on Surfrider Beach [Ed. – two nests, the first in over seventy years, were found in 2017], they roost for the winter. They begin arriving in July, numbers peak Sept-Feb, the last one leaves by May. The 2012 post-breeding arrival was first noted on July 22 when 22 were found roosting just east of the virtual enclosure erected in March 2012.

Chuck drives a fence post
(C. Almdale 3/15/12)

Plover volunteers, including members of Santa Monica Bay Audubon Society (SMBAS), census Snowies and search for banded birds nine months of the year [Ed. – now year-round]. (SMBAS also does a monthly census of all birds in the lagoon vicinity. Link to April 2017 report.) If you see one or more people with binoculars, moving very slowly through the plover enclosure or nearby, frequently stopping and using binoculars to stare at the ground, they’re looking for banded birds.

The problem is that WSPs evolved to live on barren sandy beaches. California beaches get over 200 million visits by humans every year, humans involved in their own pursuits – surfing, swimming, sunning, walking, tossing Frisbees, letting dogs run free – humans oblivious to these tiny residents of the beach, residents who simply were not built for this. They have other problems: regular beach grooming which removes the wrack, vehicular traffic, predators attracted to human refuse. Dugan and Hubbard (2003) found that Snowy Plover abundance on southern California beaches was positively correlated with the mean cover of wrack and abundance of wrack-associated invertebrates. They also found (2009) that beach grooming increased beach erosion and the need for beach replenishment. Perhaps local beach authorities could help the plovers – which are, after all, a threatened species – as well as reduce cost for sand replenishment by ending large-scale grooming (see photo above) of the beach around plover roosting sites.

We’ve found that nearly everyone, once alerted to the presence of Snowies on the beach, will watch out for them and avoid them. Very few people enter the plover enclosures we’ve erected for them over the past few years. Unfortunately, the Snowies – despite our best efforts to teach them to read – have failed to grasp the concept and often sit outside the enclosure. We plan to move the enclosure as often as is feasible.

Jamie ties a knot in the Surfrider Beach virtual fence (C. Almdale 3/15/12)

Very recently, the U.S. Fish & Wildlife Service increased by 102% the official Critical Habitat for WSPs, from 12,145 acres up to 24,547 acres of Pacific sandy beach. Surfrider Beach/Malibu Lagoon Critical Habitat was increased to about 13 acres, extending from just northeast of the pier to the colony fence. Our experience of working with the Snowies is that they rarely go beyond the area between the two lifeguard stations and much prefer the beach directly between the lagoon and ocean (except when winter storms make this section too narrow). In one sense, the more designated Critical Habitat, the better. In another sense, the timing of this designation hampers the reconfiguration project [Ed. – June 2012 – May 2013] of the lagoon’s west channels. Snowies don’t use elevated or vegetated areas. They depend upon the open beach and the wrack. [Ed. – They seem to prefer nesting – as opposed to winter roosting – among live vegetation, sticks and stones.]

People ask us why we bother with such small creatures. They’re not big and flashy like pandas, lions or gorillas.  Our answers are numerous: they’re adorable, they are so pathetically few, few people know or care, humans caused their decline, they need our help, they’re cute, empathy for fellow earthlings, they’re wonderfully interesting to watch and know, they have engaging personalities. Each and every one of us loves these little birds.

Snowy Plover PV:YB on Surfrider Beach, banded summer 2012 at Oceano Dunes, previously sighted at Guadalupe Dunes in Aug. and at Malibu in Sept. (J. Waterman 10/22/12)

We will continue with Part VI tomorrow.
[Chuck Almdale]

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One Comment leave one →
  1. May 19, 2017 10:46 pm

    Reblogged this on Wolf's Birding and Bonsai Blog.

    Like

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