CLIFF SWALLOW

Petrohelidon pyrrhonota

Order:  Passeriformes

Family Hirundinidae

Alpha Code:  CLSW                         AOU#:  612.0

Band Size:  (1C) 1

The Cliff Swallow is best know for its mud nests that adorn the eaves of buildings and the undersides of freeway overpasses and bridges.  It is about the same size as other species of swallows (15 cm).  I have seen as many as five species of swallows swooping about a body of water catching insects.  The first challen in the field is actually finding an individual and following it through the air.  But then the identification of swallows through a pair of binoculars is less of a challenge.  Fortunately, the buffy or orange rump, dark chestnut throat with a blackish or dark bluish throat, pale or cream forehead, and square tail quickly separates it from other swallows unless you are in SW Texas and Cave Swallow country.

     Cliff Swallows are found over most of the United States with the exception of the South.  In California, it is absent in the eastern deserts around Death Valley.  Common as these birds are, they have only expanded their range in the last century or so.  They were once restricted to the cliff faces in the mountains of the West and have expanded mostly due to the activities of humans (a rare exception to the rule).  Almost bridge or under/overpass is a potential site for a colony.  The colony can vary in size from a handful to thousands of nests.  Buildings near riparian areas are candidates for nests.  Non-human sites include cliffs and in one case a large Ponderosa Pine ( ).  This is the "swallows" that return every spring to Mission San Juan Capistrano in southern California  However, today this is almost a non-event, as the nearby riparian is now a concrete covert devoid of riparian vegetation (and thus insects).  (Human) Residents also tend to knock down the nests of these nuisances that defecate under their nests and dive-bomb human threats.

Bird Banding:  I suspect most bird banders encounter Cliff Swallows or, for that matter, any swallows mostly by accident.  The unsuspecting swallow swoops below three meters chasing a bug.  Most nets are set up against a vegetation backdrop further reducing the chances of a, swallow encounter.  e.g. At our Zuma Canyon banding station, we have encountered nine swallows (CLSW, NRWS, VGSW) in seven years.

     The few of us that band large numbers of CLSW probably have unique sites to catch and band swallows... rather than hanging over a freeway overpass.  In my case, there are several low culverts that I can stretch a mist net across and catch the birds as they leave or return.  Hans Bub's Bird Trapping & Bird Banding has illustration of some unique methods.

      My experience is that because of their rather weak legs, it is very easy to remove swallows from the net.  Using the Body Pluck method, it is typical to remove a half dozen birds from the net in a few minutes.

     The birds have very short tarsi, making it somewhat hard to get a band on the bird.  CLSW used to use size 1C bands but I have had no problems with size 1 bands.  The sexes are equal by plumage.  Pyle (1997) indicates that the blackish throat patch is larger on males than females, but I have not checked this.  The CP/BP are useful, but males also incubate and develop a partial BP. 

     Since I band Cliff Swallows primarily in May-July, I encounter Juv-HY birds.  The forehead patch is distinctively absent.  The throat and forehead are speckled.  The buffy-rufous edging to the tertials described by Pyle (1997) is obvious (see photo).  The birds in the colony seem to breed asyncronously or double clutch as I see fledged birds and eggs in nests at the same time.

     I have seen almost no body or flight feather molt.  Flight feather wear is 0 or 1.  Swallow feathers seem extremely sturdy and resilient.  The PB molt occurs in the wintering grounds and is over by Feb

    It is often interesting to look at the mouth of Cliff Swallows returning to the nest with a mouthful of insects.  Many times I have seen the mouths lined with winged aphids, illustrating the ability of these birds to see aphids while flying at the speeds they do.

Nests:  Although nests at my banding site are accessible, the openings are generally too small to get a hand inside to extract chicks to band.  I guess a pair of blunt tongs would work, but I am concerned about harming the chicks.  One can inspect the nest for eggs/chicks.  In this way, I have noted eggs in nests while seeing flying HY birds.

Parasites:  Colonial living lends itself to various parasite infestations.  I have occasionally nests are teeming with cumicid bugs but the adult birds do not seem to harbor them.

Adult Cliff Swallow - note pale forehead, chestnut cheeks.  Black throat is not obvious here.

HY Cliff Swallow - note forehead patch is brownish and ill defined.

HY Cliff Swallow - pale rump.  Note edging of tertials.

HY Cliff Swallow - buffy-rufous edging to tertials.