Hi All ( & Janet),

Pat Valdata's response pretty much covers how geese wind up with large 
gaggles of youngsters. It's essentially shared chaperoning by two or 
more pairs. Sometimes ducks wind up with pooled broods but the duties 
are often unshared in those cases. By coincidence there's an article in 
the latest issue of the Condor that discusses the circumstances 
surrounding (e.g. age and relatedness of birds involved, etc.) what the 
article terms "gang brooding" by Canada Geese.

The article is:
Gang Brooding in Canada Geese: Role of Parental Condition and Experience
Michael R. Conover 
<http://caliber.ucpress.net/action/doSearch?action=runSearch&type=advanced&result=true&prevSearch=%2Bauthorsfield%3A%28Conover%2C+Michael+R.%29> 

The Condor May 2009, Vol. 111, No. 2: 276–282.

The article can be viewed by Cooper Ornithological Society members or, 
for a price, by non-members at: http://caliber.ucpress.net/toc/cond/111/2

Good birding,

Walter Ellison & Nancy Martin

23460 Clarissa Rd
Chestertown, MD 21620

phone: 410-778-9568

e-mail: rossgull(AT)baybroadband.net

Observing Nature is like unwrapping a big pile of presents every time 
you take a walk.

Janet Millenson wrote:
> At Swains Lock (approx. mile 17 on the C&O Canal towpath) this afternoon I 
> encountered two adult Canada Geese watching over *20* goslings. No other 
> adult geese were nearby. Canada Geese don't have broods that big, do they? I 
> assumed it was the parent birds watching over the young'uns while they 
> grazed -- but might the adults have been two females instead, each with her 
> own group of goslings?
>
> Please enlighten me, you goose gurus out there. Thanks.
>
> Janet Millenson
> Potomac, MD (Montgomery County)
> 
> ----------------------------------------------------------------
> "Look at the birds!" -- Pascal the parrot 
>
>
>