[Taxacom] taxonomy, migration, and longevity

Kenneth Kinman kennethkinman at webtv.net
Sun Sep 25 22:33:01 CDT 2011


Dear All,
       I really enjoy this time of year when so many migrations are in
full swing.  Monarch butterflies, robins, sparrows, and hummingbirds
have been flying through for weeks now, and entering that time when
cranes and other waterfowl join them in a frenzy of southward movement.       
      However, such North American migrations (which are well-studied)
may be just the tip of the iceberg of migration research.  For instance
the migration of dragonflies from India to Africa, only discovered in
recent years (at least by science) is truly amazing in its length and
that so much of it occurs over open ocean (see weblink below for one
article).  Even monarch butterfly migration seems relatively easy in
comparison.  It is also interesting that some birds (which feed on
dragonflies) seem to follow the dragonflies as they fly across the
Indian Ocean.  Sort of like little packets of protein-rich snacks flying
along with them.         
      Perhaps even more extraordinary than the lengths of those
migrations is that they continue without much in the way of human
conservation efforts (at least so far).  This is in contrast to very
intense conservation efforts to protect certain migrators in North
America.  Could many of the species of hummingbirds migrating through
North America have maintained their numbers (without flower gardens and
nectar-feeders maintained by large numbers of gardeners and bird
watchers) in spite of the negative impacts of climate change and
environmental degradation?  And whooping cranes survive today only
because of intense conservation efforts over many decades.  On the other
hand, not much chance that an imperiled dragonfly would get the
attention here that is paid to cranes, hummingbirds, or monarch
butterflies.            
        -------Ken Kinman    
        
http://www.wildlifeextra.com/go/news/insect-migration.html

P.S.  Given the energy requirements of monarch butterfly migration, it
does not surprise me that they have such short life spans.  However, it
does surprise me that hummingbirds average 3-5 years and even live as
long as 12 years, given their small size and extremely intense energy
requirements (do any tiny rodents or shrews fare so well in longevity?).
Bears have it easy in comparison, given their large size and usually
only going into torpor once per year.  Many hummingbirds have to go into
torpor night after night after night, and they have to compete with
other hummingbirds over food resources during the day.  Combined with
migration pressures, they have a very tough time of it compared with
bears (which tend to migrate less and have a greater range of food
resources, except for pandas which are heavily dependent on bamboo).
Anyway, if I am to be reincarnated as an animal, I think I want to be a
generalist omnivore that does not need to migrate very far).  :-)  






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