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Posted by: atowhee | April 22, 2018

DIPPERS FLEDGE FOR EARTH DAY

“I fledge allegiance to this stream, in which I stand…”   –anon. dipper

“He is the mountain streams’ own darling, the hummingbird of blooming waters, loving rocky ripple-slopes and sheets of foam as a bee loves flowers, as a lark loves sunshine and meadows…”                                                     –“The Water-ouzel” by John Muir

This morning I re-visited the dipper nest under the chosen bridge along Baker Creek Road.  The opening had been enlarged; the nestlings are now fledglings.  Somewhere along this clear, churning creek the family of two adults and at least three young are now hunting their daily meals.  These newly minted dippers will be loyal to Baker Creek.  They will travel up and down the upper stretches, perhaps visit a tributary or two.  They will learn the skills needed to be dippers.  Swimming against the  pull of the current.  Looking beneath stones and litter on the  bottom of pools.  Checking the wet, moss-covered rocks right along the creekside.   How to shake a caddis fly larva so it comes out of its leathery cocoon. How to sing that long, gurgling, musical song.

Muir again: “No need of spring sunshine to thaw his song, for it never freezes.  Never shall you hear anything wintry from his warm breast, no pinched cheeping, no wavering notes between sorrow and joy; his mellow, fluty voice is ever tuned to downright gladness, as free from dejection as cock-crowing.”DPR NEST EMPTYHere is the nest with opening enlarged.  You can see through to the back wall which is simply the cement of the bridge.  Below, is a large mossy rock I placed along the creek edge so I could easily stand oppositge the nest.  The dippers themselves used that same rock, leaving their whitewash (dipperwash, if you will) as evidence.DIPP-WASHBelow is upper Baker Creek where the dipper family is not making its nomadic living.  If the aerial density of insects is any indicator, they should do well.  Today there were gnats, small flies, pale tiny moths and a few large white butterflies flitting about.  Some of those surely come from aquatic larva on which the dippers can feed.  Dippers will also take tiny fish and other little vertebrates.BAKR CREEK

Here is what the Birds of North America has to say about the adults feeding nestlings.  It still does not quite answer my questions about double visits by single adult in rapid succession. Maybe next spring I can pitch a tent and just live by the nest for a few days and figure it out….  Actually dippers may nest twice in a summer rich with streamy foodstuffs.

“Feeding

“Both parents feed young, although lone parent can raise young. Parents give grawk call (see Sounds: vocalizations, above) as they approach nest [my italics]. Young birds call loudly at feeding time, especially as they get older. [Amen!] Depending on nest site, parent alights near nest, then flies, hops, or walks rapidly to nest; parent may cling to lower edge of nest or hover while delivering food. By 5–6 d, young can reach for food through opening (Hann 1950). Food is delivered quickly (5–10 s; Bakus 1959a)); toward end of nestling period, feeding may take only 1 s (Hann 1950). Some observers report only 1 nestling fed at each nest visit (Cordier 1927, but in Southeast Alaska, two or three chicks are sometimes fed at a single visit (MFW, R. Danner, pers. comm.). Shortest time observed to leave and to return with food is 20–30 s (Bakus 1959a).

“Parent feeds nearest young; nestlings change places at defecation time. Older nestlings excrete from nest and frequently shift positions, so food is fairly well divided among them (Rishel 1925). Nevertheless, brood reduction appears to be rather common (see Demography/Recruitment).

“Nestlings are fed same food as adults eat, but often in different proportions. In Gunnison Co., CO, nestlings fed 63.5% mayflies, 24.5% stoneflies, and 11.5% caddisflies. Food is gathered within 300–400 m of nest (Hann 1950). One report of parent washing food in water before feeding it to young (Evenden 1943). On some streams in Southeast Alaska, salmon fry are a common prey delivered to the nest, even to very young chicks; the maximum number of fry delivered was 4 per nest visit and 17 per hour (Willson and Hocker 2008b). Chicks in late-summer broods on salmon-spawning streams are also fed salmon eggs (Willson and Hocker 2008b, MFW).

According to some observers, feeding primarily by female (Hann 1950Bakus 1959a). In 50 h of observation at 3 nests, female made 204 of 370 feeding trips, male 166 (Sullivan 1973). At one nest, female fed 8 times/h, male fed less often but more frequently between 1000 and 1400 h, usually when female brooding young; together parents made 12 trips/h (Cordier 1927); at another nest, 20–26 trips/h (Rishel 1925). In Missoula Co., MT, more frequent feeding up to 2–3 d before fledging: every 1–7 min (usually every 2 min; Goodge 1959). On same stream, Sullivan (Sullivan 1973) recorded fewer feeding trips—8.76/h; he noted that feeding trips peak 15–17 d after hatching, at 4 trips/nestling/h, with rapid drop to 1.5/trips/nestling/h by 23 d. In Southeast Alaska, feeding rates varied from 0 to 35 trips per hour (usually about 10-17), with roughly equal contribution of both male and female (Willson and Hocker 2008b, 2009b). Just before fledging, number of trips declines; this correlates with weight reduction which may encourage departure from nest (Sullivan 1973).”

CLICK HERE FOR GALLERY FROM FRIDAY, THE LAST DAY I SAW THE YOUNG IN THE NEST.

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