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Active Since: October 18, 2020
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  • Aline
    Participant
    Thanks for a great course.  I regularly go back to the crow/raven ID quiz because they are hard to tell apart in pictures, but easier once you know what to look for irl. Urban/suburban smaller crows:  I haven't read the New Scientist feature on Ms. Heiss's work, so I don't know all the information learned from her work.  But I wonder if also crow competition had anything to do with which crows moved into the city.  As in, did smaller crows move to where there is less competition?  I'm statistic-illiterate, but the ranges among the difference indicators -- bill width, weight, calcium -- between rural and suburban crows don't rule out that the suburban crows were simply smaller to begin with and had they stayed in the rural environment, some of them still would have been that small.  Looking at it from another angle, if a cohort of larger, rural crows were moved into the city, would some of them remain large in spite of the city diet? The idea that suburban crows are adaptively smaller so that they have lower nutritional demands to me just means that they can't get the nutrition they need to grow larger.  In the scheme of things, organisms "want" to be larger because size is an advantage in competition for territory, food, mates.  That the nutritional value of food in the city is poorer than in the rural environment may be a factor in why smaller crows live in the city.  They're settling, making do.
  • Aline
    Participant
    Greetings, everyone! This was a wonderful segment, thank you. Crow behavior:  I haven't had a chance lately to watch crows, but spring/summer 2019 I watched a family forage outside a window at my parents' place, which was kind of a hilly strip of land shaded by redwood and pepper trees (this is on the west coast).  I put out some food (sorry, I know now not great choices, but could have been worse) like almonds, granola, oats, maybe some strips of turkey coldcuts.  It was a family with relentlessly begging kiddies. One bird usually came and perched on a tree overlooking the area where I laid out the treats, and it scouted out the area; then after a while, the group would arrive.  Then one would sit up the hillside as sentry.  The adult birds really did look harried.  The almonds were not edible for them as whole almonds; I found some spewed back up.  But the birds did like almonds and started to hold them down with a foot and peck vigorously at them, eating the shards. Sometimes only one bird would arrive and pick up something and fly away with it.  I don't know if this bird was in the same family as the birds who came in a group. I remember WNV well.  I live on the east coast in a big city.  There used to be crow calls and I would see crows in the area, and then all of a sudden, there weren't.  I was very sad about this.  Only now (2020) am I starting to hear a few.  Whenever I see standing water, I get sad, because standing water supports mosquito population growth, and mosquitoes are how WNV gets around.  I will never qualify as a buddhist, because I do not refrain from killing mosquitoes at every opportunity.  The best way to curb this disease, and as a side benefit, diseases like Zika and anything else that goes around by mozzie, is to remove mozzie habitat.  Not easy in this part of the country.  
Viewing 2 posts - 1 through 2 (of 2 total)