2011 Spring Class #2- Molt

Spring Class #2    5-3-2011

First what shorebirds can be found in spring and fall

Black-bellied Plover Common Common
Am. Golden Plover Rare Fairly Common
Pacific Golden Plover Uncommon Fairly Common
Snowy Plover Local Available Local Available
Greater Yellowlegs Common Common
Lesser Yellowlegs Rare Common
Solitary Sandpiper Rare Uncommon
Willet Very Uncommon local Local, available
Wandering Tattler Uncommon Uncommon Early migrant
Spotted Sandpiper Common Common
Whimbrel Common Common
Long-billed Curlew Very uncommon Uncommon
Hudsonian Godwit Very rare Rare
Marbled Godwit Common Common
Bar-tailed Godwit Very Rare Rare
Ruddy Turnstone Common Uncommon
Black Turnstone Common Common
Surfbird Common Common
Rock Sandpiper Very Uncommon Uncommon
Red Knot Common Uncommon
Sanderling Common Common
Semi-palmated sandpiper Rare Uncommon
Western Sandpiper Common Common
Least Sandpiper Common Common
Baird’s Sandpiper Rare Uncommon
Pectoral Sandpiper Rare Uncommon
Sharp-tailed sandpiper Very rare Very uncommon
Dunlin Common Common
Stilt Sandpiper Very rare Uncommon
Buff-breasted sandpiper N/A Rare
Ruff  Very rare Uncommon
Short-billed sandpiper Common Common
Long-billed Dowicher Fairly common Common
Wilson’s Phalarope Rare Uncommon
Red-necked phalarope Uncommon Fairly common
Red Phalarope Rare Uncommon after storms

In spring in WA there are about 23 common shorebirds, few rare

In Fall in WA there are about 25-26 common to uncommon with about 10 more rare

Tails and Wings  from P 28 in D. Paulson’s first book.

Look that many birds which are Probers tend to copy in appearance Sentinals that they associate with.

Sanderling and Dunlin will fly together, both stripe tailed, bold wing patterns and similar size

Red knot and BBPL both conspicuous wing patterns and white rump, Black-bellied is a sentinel and Red knot a prober.

Note the 5 rock sandpipers can be IDed primarily on their tail patterns, Surfbird and Turnstones band tailed, Tattler plain tailed,  Rock Sandpiper stripe tailed.

Sentinels vs. probers.  See ABA article in 2007 by D. Paulson.

Flocking is social, depends on flight patterns and similar sizes.

Birds in tight coordination flocks need to be very similar in size.

A birds pattern says come fly with me, a social message

Surfbirds, Turnstones, Rock Sandpipers

Dunlin and Sanderlings

Curlews and Godwits

BBPL and Red Knot

Sentinels see the predator first, usually have their head up, give a loud call.  Plovers, Trigines Palaropes, Upland Sandpipers, Curlew

Probers keep their head down, more at risk depend on

Dunlin, Stilts, Dowivhers, Snipes, Peeps.

These are mutually beneficial  Sentinals keep an eye out and have loud calls, probers have large flocks, have softer calls, space less, have heads down.

Convergent evolution:  Curlew & sentinals, Yellowlegs, Phalaropes and Dunlin

In theory probers should increase awareness when alone, and have a higher predation when no sentinels around.


Molt is mostly about the flight feathers, the wing and tail feathers.

Primaries are attached to the hand.

Secondaries attached to the ulna.

In theory to be a true tertial needs to be attached to the Humerus.

Primaries usually #10, numbered from inner to outer.  Usually shed from the inside out.

Secondaries vary in number, numbered from mid-wing inward.  14-38 depending on how  long the wing is in the species.  Usually shed from the outside in and from the inside tertial outward both at the same time.

Tail: Most birds have 12 tail feathers, inside R1 out to R6 on each side.  Usually shed from the inside out with some exceptions (like woodpeckers)

Greater coverts cover the secondaries, primary coverts cover the secondaries.  Median coverts cover the primary coverts.

Scapulars are important in that they are very noticible in standing birds.

Primary coverts usually shed with the primaries they cover.


Modified Humphrey-Parkes Classification System

2003 by Howell.

All You Ever Wanted to Know About Molt

But Were Afraid to Ask

Part II: Finding Order Amid the Chaos

by Steve N. G. Howell

Now all molts are names for the molt that is coming in, i.e. pre molts.  This is from an ABA article Oct

Molting is the regrowth of feathers.  That is all we are concerned about, the growth of a new feather generation, not at all about color, just the growth of the feather.

There are 4 basic strategies:

Simple Basic Strategy SBS  same plumage all year – not many, Albatrosses, some petrals, barn owl.

Wear their juvenile plumage ofor a whole year.  Ne complete molt per year in the fall.

Complex Basic Strategy  CBS   Towhee, Only difference is a formative plumage in the first year.

Simple Alternate Strategy  SAS  One different plumage in the spring, the alternate plumage.  Two molts per year, have a complete fall molt, and a usually incomplete alternate molt in the spring.

Complex Alternate Strategy CAS  Have an additional molt out of juvenile into formative molt, i.e. preformative molt, in the first year, then two a year (3 in the first year)

Birds have one complete molt every year as a general rule, large birds maybe every 2 years.

Other molts are either limited, partial or imcomplete.

What triggers molt?  Length of day, temperature, and suppression of hormonal function activation triggers a molt.

New feathers are in sheeths, and made out of keratin, i.e. pin feathers.

Plumage:  to describe the color of the birds we can use the term aspect.  So in Humphrey Parke we use phrases like adult plumage aspect APA,

Most birds hatched either naked (altrical) or downy (precocial)  The first true feathers are the juvenile feathers, i.e. the B1 feathers.  Most birds in the F1 plumage have an APA.  They retain a few juvenile feathers, so you can sometimes tell they are in formative plumage.

After the birds are adult you say that they have a definitive pre basic and definitive pre alternate molt.  DPB and DPA molt each year.

A few birds have two downy plumages, e.g. flamingos, penguins.  Some have a supplemental molt, i.e. one that is extra and does not fit in.  Possibly Marbled Godwit has an extra very limited molt where the red in the breast becomes brighter as they move north.  Usually after the alternate molt to improve their breeding success.

Some birds have more feathers in the winter than the summer, for warmth.  Big birds have more feathers than small birds.

Birds have to molt.  They cannot survive without molt, so it’s more important than breeding.  More important than migration.  Molt is a high energy cost process.  Most birds do not molt their flight feathers during migration.  Some like dowichers suspend molt during migration and resume at staging areas enroute.

Dark feathers wear the slowest, light feathers the fastest
Small birds generally separate molt from breeding.  Larger birds can molt during breeding, but not while laying eggs. Female hawks may start molt prior to laying eggs, suspend this to lay eggs, and then finish after eggs are hatched.  Males are smaller so wait to start until after the birds are off the nest and still finish on time because they are smaller.

Timing of molt may depend on the length of migration, others go to a staging location enroute on migration.  May depend on food supplies, other factors.

IN 1983 no body knew where black swifts winters, but they had never been seen molting in NA, and so we knew they had to winter in South America.  So by looking there they were found in S. America. Opposite with Cave Swallows, known to be in molt in NA, and finally found wintering in Mexico.

Molt sequence:  Flight feathers first P1à P6, then secondary molt starts both ways from the middle on out.

Color of feathers can change based on when the bird is born and when they molt.  Male House finches, CBS, if they molt Augà Oct in first year can be red, if molt in Julyà Nov can be partially red or yellow. If they molt after Nov they can be female aspect.  (pre Howell in Molt book)

Types of molt:

Complete all feathers

Incomplete:  all except but some flight featehrs

Partial:  Most body but no flight feathers

Limited: Some of the body but not all.

Molt Contrast:  Some of the coverts, some scapulars may be adult like and others juvenile like.  This contrast between new and old feathers is called molt contrast.  Can help with aging some species.

4 types of wing molt:

Standard sequential  P1àP10, Secondaries start about when P6 is molting, starting from the outside in and inside out.  Meet in the middle.   Eccentric sequential is a variant of this.

Synchronous wing molt:  simultaneous dropping of the wing feathers.  Typical of larger birds.  No flight.  Loons, greges, murres, waterfowl, puffins.  Dippers shed P1-6 synchrounously, then P7-10 seqentially.

Stepwise:  Old term is Stauffelmauser.  Long winged birds that weigh over 1 Kg.  Starts where the last molt left off and at P1.    Think of Golden Eagles.  Molt about from P1 à P6 or P7.  Second molt goes P1 and P7 or 8.  In third year may start at P1 P4 and P8.  Osprey has an accelerated stepwise molt.  Some are obligate.  Because of their size they have to do this.  Others are opportunistic stepwise molters, especially female large buteos.

Factors affecting molt.  Birds locked in by their genetic ancestry.  Food can affect molt.  Body size affects molt.  Migration strategy affects molt.  Most resident and short distance birds tend to be CBS.  Most long distance migrants tend to have an alternate strategy.  Habitat is important.  Birds deep in the forest tend to be CBS.  Woodpeckers, thrushes etc.  Edge birds tend to be CAS, in the sun more.

Birds that have the least amount of time not migrating molts the least, longer migrating molt the most.


3 types: 

Pigmented Carotinoids and melanins. Melanins black, brown and rusty.  Synthesized by the bird directly. Provide strength.  Carotinoids provide bright colors, from the diet, needs to eat something in the diet and synthesize it, reds pinks, oranges, yellows.

Structural Blue and white, produced by interference with light rays.  Fine structures in the feather bend the light to produce the color.  Blue absorbs everything but the blue and reflects the blue.  Like Stellar’s jays, indigo buntings.  Keratin scatters light.  No pigment scatters light.  Irridescence varies with viewpoint and is due to fine structures in the feathers.  Fine structures on the gorget in Hummingbirds reflect the light.  This changes with the angle of view.  Cosmetic is the staining of feathers by the bird.  Like Sandhill Crane puts mud on the feathers.  Reddish blush on the gulls is dietary.  Staining on swans and geese is feeding in rust deposited water.  It is incidental.  Not intentionally applied, so not cosmetic.



Fall 2010 Class #2 Focus on Molt

Tonight is all about Molt

Look at the Howell ABA article table of molt.

We will use the Humphrey Parke System.  It’s all about feather growth, i.e. molt.  Not about color.

Other systems are the Calandar Year molt system.  The problem with this is this can be more cumbersome re what year the bird is in, etc.  Pyle uses this.  Another system is the Life Year strategy.  This works good for Northern Hemisphere birds, but is awkward when birds cross the equator.

See article by Howell All You Ever Wanted to Know About Molt but were Afraid to Ask Part II Finding Order Amid the Chaos

Here is a link to the Slater Museum Blog with many posts on birding and other topics to browse

Here is a Dennis Paulson post on Molt.


4 strategies.

Simple Basic Strategy (SBS)

Complex Basic Strategy (CBS)

Simple Alternate Strategy (SAS)

Complex Alternate Strategy (CAS)

Complex means birds shed their juvenile plumage into formative plumage in the first year.

Alternate means the birds have an additional molt each year, almost always a partial molt in each year, usually into breeding plumage.

In HP we talk about cycles, not years.

Here are some terms to learn the definitions of:

Simple Basic: Albatrosses, petrels, barn owls, a few others.  In the fall there is a complete molt in all birds.

Limited: body & head

Partial: this plus some coverts, scapulars

Incomplete: above plus some remiges.

Complete: all feathers.

Complex basic strategy:  In the first cycle only, the bird has a preformative molt into the formative plumage in the first fall.  Then has just one pre-basic molt each year.  This pre-formative molt is usually limited, partial, or incomplete.  Example: towhee.  All black juvenile plumage.  Then they disappear; have a pre-formative partial molt losing all but flight feathers to look like an adult, except for worn primaries.

Simple Alternate Strategy:  In first year birds carry juvenile plumage until the first alternate molt.  This can vary in time from fall to winter. Think large white headed gulls.  Carry juvenile plumage until Sept.  Then have molt of some scapulars, etc. into A1 plumage.  Thereafter each year have one complete basic molt, and one partial alternate molt.

Complex Alternate Strategy:  First year birds have two inserted molts after juvenile.  F1 molt is usually partial, then later in the first year is the A1 molt.  Thereafter each year have a partial PA molt, and a complete PB molt.

Difference between formative molt and basic molt is that the PF molt is usually not complete.  Basic is complete.

Examples:  All passerines have a complex molt strategy.  Look at the table for these by family.

Here is a link to the table Ken used in class.   http://www.prbo.org/cms/docs/terre/Howell%20Birding%20molt%202003%20part%202.pdf

The pre-basic, pre-formative, and pre-alternate terms refer to a molt into the basic, formative and alternate plumages.

How do we recognize molt.  Obviously look for gaps in wings and tails.  If these are present, we say the bird is in active molt. If in active molt the bird is in transition from one plumage to another.

Injury to feathers.  Sometimes if you see a bird with assymetric flight feathers missing, especially not in the fall, it may be damaged feathers.  Birds often replace these damaged feathers.  Some birds suspend molt, and leave gaps for periods of time.

Molt Limits + Molt Contrast is the contrast between the new feathers and the old feathers being replaced. Often in the fall will see bright feathers being replaced by gray or plain feathers.  May see molt limits in the scapulars or coverts.  Sometimes you can age first year birds this way

Feather wear:  new feathers are not frayed, usually rounded and fully formed, don’t droop.  Old feathers often brownish, frayed, and often narrow.  Especially primaries, sometimes can be droopy.  As new feathers grow, they passively push out the old feathers.  Sometimes the old feathers become loose, and can droop.  As a rule of thumb, juvenile feathers are weak, and need to be replaced soon.  Hawks often keep their juvenile feathers a year, because as they grow them more slowly they can attain more keratin, and be more durable in the longer time in the nest.

Molt of remiges usually starts at P1 and when it gets out to about P6 the secondaries start, usually at S1 and inward from there.  Most birds molt sequentially.  Then the tertials start, and the tail is last. Tail starts form the inside out, starting with R1 and working outward.  Woodpeckers are an exception, they molt R2-6 first, then molt R1 later, to facilitate feeding techniques.

Feather wear.  Dark parts wear more slowly.  Look at gulls. Early in the year the white tips are big, later by spring the white tips can become smaller.  Another example is least sandpiper.  Scapulars white and gray tips in the spring, but by fall look almost all dark. Starlings wear off the non-black feather tips to go into breeding plumage.

Early in fall migration, shorebirds, adults in worn plumage, juveniles have very fresh plumage.  Later adults look very fresh, and juveniles look more worn.  Western Sandpipers for example seen on our trip.

Easiest way to study molt is at your feeder, or at the park in ducks.  You can study the progression easily this way.

Molt can be suspended, often larger birds suspend their molt in the winter.

How can this help us in our field identification?  Presence of wing molt can be useful.  Absence is less useful.  Sometimes species can be IDed at some times of year by their molt.  Leaches vs. Band-rumped storm petrels off Carolina in summer.

Golden plovers in California.

Hammond’s flycatcher.  In fall Hammonds molt on breeding grounds or near.  So in fall a molted empid in the west is Hammonds.  All others molt later.

In Texas cliff vs. cave swallow.  Cliff molts in S Am.  Cave molts in N. Am.

In So Cal nighthawks in molt in the fall tells us it’s a lesser nighthawk. Common nighthawks don’t molt until wintering grounds.

Only jaeger that molts off CA is Pomerine.

Western Sandpipers molt off west coast, Least don’t molt until in S America.

Now refer to Ken’s cumulative table of shorebird molting.

Look at the two basic strategies for molt, N. Hemisphere and S. Hemisphere. This is where the birds winter.

Northern  Hemisphere Strategy:  partial to imcomplete preformative molts.  Don’t include remiges.  Rapid & early PB molt.  PA molt is well defined, and is on non-breeding grounds.  Think W. Sandpiper.

Southern Hemisphere Strategy: Incomplete to complete preformative, remiges eccentrically or completely molted.  In PF many shorebirds have eccentric wing molts. Usually involved P9 & P10.   Note more molting in the long distance primaries, those which are more exposed at rest.   Protracted PB molts. May start body, and even wing molt on the nest or in early migration, usually on the wintering grounds Jan – April.   PA molt often overlaps with shedding of remiges.  PA molt can overlap with PB, more often PA molt happens at molt sites on the way to breeding grounds.

Over-summering:  relates to body size, migration distance.  Larger birds and longer distance migrants tend to over-summer in the first year.

Snowy plovers molt in N A.

Articles to check out:


Migrants,  Mono Lake,  Monsoons, and Molt


All You Ever Wanted to Know About Molt But Were Afraid to Ask Part II: Finding Order Amid the Chaos


A Tale of Two Strategies: Fall Molt of Adult Dowitchers


Active Flight Feather Molt In MIgrating North American Raptors