The occurrence of Peregrine Falcon in central California, including Monterey County, is complex. There are resident birds that breed here in remote eyries, mostly along the Big Sur coast. There are wintering individuals that arrive here from breeding sites far to the north (like those that regularly use the Embassy Suites sign in Seaside, above), and there are passage migrants in fall and spring. Three subspecies occur locally, but have differing timing patterns. This web project introduces these variations. It is something that I have only recently become attuned to, as ebird permits observers to enter Peregrines by subspecies. It is something worth learning, and I'm just starting.

A starting point is to understand that for field identification there a just two essential age groups: (1) adults in basic plumage and (2) juvenal-plumaged birds in fall migration and early winter [these molt into basic plumage by spring]. These two plumages are easily separated: adults are barred below, while juvenals are streaked below. Adults have yellow lores, while juvs have bluish lores. This shows very nicely on these photos (below):

• an adult, with California Gull as prey, at Salinas River mouth MTY on 31 Jan 2007 © Jeff Poklen
• a juvenal, with American Coot as prey, at Shoreline Park, Mountain View SCL on 8 Nov 2008 © Don Roberson

Here is an example of our resident Continental Peregrine, taken 20 Oct 2006 at Big Sur R. mouth (© D. Roberson). First thing to notice is that the malar stripe is so broad that it covers the entire auriculars – the entire dark heard is like a helmet. Second, notice the extensive orangey wash in the underparts, typical of P. p. anatum in moderate latitudes. There is barring across the flanks and belly, but not on the breast. The overall 'tone' of the upperparts in 'medium,' neither particularly dark nor particularly pale.

Historically there were 24 known eyries of Peregrine in MTY, but they all were abandoned by the mid-1960s due to the egg-shell thinning properties of DDT and derivatives. The banning of DDT in the 1970s, and the re-introduction project in the 1980s by the Santa Cruz Predatory Bird Research Group, headed by Brian Walton, brought this species back to recovery in MTY. All re-introduced birds, and all eggs replaced in wild nests, were on the anatum subspecies (White et al. 2002). Today there are 6-9 breeding pairs along the Big Sur coast (Roberson 2002).

There is a lot of variation in the plumages of Continental Peregrines. While our resident birds may be rather rusty below, many migrants from farther north are not. And then there is a lot of variation in the width of the malar stripe.

The upperparts of this bird (another wonderful shot © J. Poklen) are medium in tone, with decidedly paler rump and uppertail coverts, and a barred tail that is also in the mid-gray range. More shots are on Jeff Poklen's web site.

I also believe that the bird shown below, with a California Gull as prey from Rio Del Mar, Santa Cruz Co., on 26 Jan 2008, is a Continental Peregrine, but from somewhere rather far north of us. It also lacks orangey tones in the underparts, but is medium gray in upperpart tone and has a very broad malar (but not a complete helmet). The wings do not reach the tip of the tail.

This type of Continental Peregrine plumage is very like the birds that winter on the Embassy Suites (right, photo 27 Mar 2006 © D. Roberson ), and on the "smoke-stack" on Monterey Bay Aquarium. Some believe it is the same couple of birds that use these 'traditional' perches, but there is rather little actual evidence one way or the other. Wintering Peregrines have high fidelity to specific wintering spots, and may live 16-20 years (White et al. 2002), so presumably the same birds return each winter. Presumably the older returning birds establish dominance at these perches, but as these are highly desired locales for Peregrines, I suspect that other Peregrines use them when the "wintering resident" pair is not around (such as one seen on Embassy Suites 3 July 2006; Bill Hill). Peregrine pairs do not migrate together, so it is possible that the two birds seen annually are not actually paired to each other, but rather have high fidelity to a wintering perch. Or they may be a pair bond — there are plenty of things we don't know.

However, we can tell by their non-orangey plumage they are not from the population of our local breeding Peregrines. They likely breed thousands of miles north of us. No wonder the "nest box" put up by Embassy Suites is an abject failure! No Peregrine has ever checked it out for breeding purposes, although one may roost near it.

In fact, DNA studies of the three American subspecies have shown no greater variance then populations of the same European subspecies in northern and southern Sweden (White et al. 2003). In other words, there is substantial gene flow between populations and the 'edges' of what we are calling subspecies are very 'muddy.' We can probably only recognize really typical individuals of any race.

Tradition says that the Embassy Suite and Aquarium Peregrine arrive on Halloween and leave on Tax Day (April 15). My MTY data-base shows records from Embassy Suites as early as late Sep (and 4 Oct for the Aquarium) and as late as 1 May, but late Oct–mid-April is likely a very good average arrival and departure pattern.

There are no photos (yet) of Tundra Peregrine in MTY; indeed, there are only a few sight records in fall migration. Adults differ from Continental Peregrine by averaging paler with broader white forecrown; averaging longer wings (reaching the tip of the tail); they tend to have a very narrow malar stripe; and they tend to have a pinkish-buff wash to the belly. These features seem mostly present in this photo from the south end of the Salton Sea, Imperial Co. (24 Nov 2006 © D. Roberson). Wheeler (2003) shows tundrius as wintering in the Imperial Valley.

Tundra Peregrines apparently winter north to Santa Barbara, so it may be supposed that a few could winter here. Certainly there must be passage migrants spring and fall. Fall migration begins in September (Wheeler 2003).

Many Tundra Peregrines have a malar even narrower than the one above. This photo of a juv tundrius from Santa Barbara (right, ~Dec 2006 © Oscar Johnson) shows that narrower malar stripe very well. Indeed, the narrow malar may be the most important feature on this race. Juvenal Tundra may show a very pale whitish-buff head, and may stand out as "blonde" Peregrines (Wheeler & Clark 1995, Wheeler 2002). An extensive, pale supercilium — as on this bird — may be another typical feature.

As most birders know, most of the Peregrines from southern Canada and the United States were subject to intensively efforts to re-establish them in the 1980s & 1990s. Many of our birds today originate from those efforts. According to White (2002) and Wheeler (2003), all the re-introduction projects in western North America involved only anatum birds. East of the Rockies, however, the efforts to re-establish the species were considered more critical, and involved birds from all three North American population plus two races from Europe. Thus in eastern North America one may encounter birds with a higher mix of characters, including dark pealei-like birds. Here in the West, we do not have that problem. No re-introduction efforts were made in Alaska, for example, so our migrant birds are all "pure" stock.

It is an extremely dark bird above, with rump about the same tone as the blackish tail, and is extensively dark on the underwings. It has a medium-broad malar stripe and no hint of orange or rust coloration below. The scanned flight shots are not good enough to determine if the auriculars are streaked, but that point is quite obvious on this juvenal bird (left) from south San Francisco Bay on 8 Nov 2008 (left © D. Roberson). Apparently, streaked auriculars is a diagnostic character of pealei (although some paler individuals may lack it; Wheeler 2003).

There is a specimen of Peale's from Pacific Grove on 1 Jan 1910 (Roberson 2002), and 6 records of Peale's in the ebird database for Monterey County within the last 4 years, all between 16 Oct–5 Mar. All but one are from the immediate coast (Pt. Pinos, Asilomar, Salinas R. mouth) except for one at Cone Peak 21 Oct 2006 (B.L. Sullivan).

The very dark plumage of Peale's Peregrines parallels that of the dark suckleyi Merlins that winter here on the central coast. Both populations breed in the humid forested areas of the Pacific Northwest, and average much darker than 'typical' birds.

The very dark look is also evident in flight (right; same bird), and includes the very dark underwings. I will certainly try to identify the subspecies of local Peregrines that are encountered, if looks are good enough, but it must be cautioned that there is a range of overlap between these three types.

Our Peregrines take a wide variety of avian prey, apparently focusing locally on Rock Pigeons, gulls, ducks, coots, and large shorebirds. The young Peale's Peregrine that is featured in these photos (© D. Roberson) had taken a coot at Shoreline Park, Mountain View, and the feathers were flying as it consumed the meal (below).

Photos: All photos © Don Roberson, all rights reserved.

Literature cited:

Roberson, D. 2002. Monterey Birds, 2d ed. Monterey Pen. Audubon Soc., Carmel, CA.

Wheeler, B.K., and W.S. Clark. 1995. A Photographic Guide to North American Raptors. Academic Press, London.

Wheeler, B.K. 2003. Raptors of Western North America. Princeton Univ. Press, Princeton, N.J.

White, C.M., et al. 2002. "Peregrine Falcon" in Birds of North America (F. Gill, ed.), no. 660. Birds of North America, Inc., Philadelphia, PS.