FOSSIL BIRD NEST
Mono
Lake in eastern California is an unusual lacustrine environment. It
is hypersaline and quite alkaline (pH is about 10). The size and
chemistry of modern Mono Lake has been strongly influenced by human activity,
principally by the diversion of water from the inflowing Owens River to the Los
Angeles urban area. About three dozen species of birds use the lake as a
resting site during migration, as a source of food (brine shrimp), and as a
nesting site.
Bird nests along the shores of Mono Lake can be
subject to inorganically- & biogenically-induced encrustation by calcite
and aragonite (CaCO3) (calcium carbonate) when lake levels rise
after storm/flood/runoff/snowmelt events. The specimen below shows a bird
nest having two eggs encrusted by calcium carbonate (“calcareous tufa”, a
friable precursor to travertine). The hollow tubes surrounding the eggs
represent molds of the stems of shore plants.
I’m calling this a fossil bird nest, but I doubt it is
Pleistocene or older. It’s more likely to be Holocene in age, and it is
probably a California
gull nest.
Bird nest (likely a California gull nest) encrusted by calcareous tufa from the
shores of Mono Lake, eastern California, USA.
(Cranbrook Institute of Science collection, Bloomfield
Hills, Michigan, USA)