Musings of a roaming nature nerd

Vireo Chronology

The fact of the matter is that the real world, (ie. nature; the world outside of the world we have created for ourselves) is a rough place. I find that when I work in environmental education I feel an even keeled sense of satisfaction. There are good days and there are bad days, but over all I know that slowly, the work I am doing is nurturing in students the potential for life long investment in our planet. Doing field biology is like an emotional roller coaster! The highs are super high: the thrill of finding a new nest; the excitement of seeing fledglings for the first time, fluttering and begging for food. But the lows are super low: yet another nest full of eggs just about to hatch, depredated and knocked to the ground; a baby bird being eaten in front of you by a scrub jay; oh, none of it matters because the highway is being expanded into their habitat anyway. Sigh…

Those variations are of course what keeps things ticking. Without some tragedy and some success we would be a rather unbalanced world. Today, I thought I’d share one of the highs which depicts the full successful breeding cycle of the Least Bell’s Vireo. These photos are not from the same nest, because I’m not lucky enough to capture every nest at the right moment, but honestly, the Vireos all look the same so this gives an idea of the chronology of their spring time cycle!

After building the nest together for 4 days, the male and female rest for a day. On the 6th day of the cycle she will lay the first egg.


A typical full clutch for Least Bell's Vireos is 4 eggs.


Both the male and female incubate the eggs which take 14 days to hatch. They begin incubation when the second to last egg is layed. This male must have been excited because he was incubating just one egg!


Day Zero or Hatch day! These brand new babies are about the size of your thumbnail.


By Day 5 the nestlings are demanding food about every 15-20 minutes.


Day 9 and these babies have almost outgrown the nest. In three more days they will be out of the nest with their parents.


A tiny 2nd day fledgling waiting for a tasty morsel to be brought from mom or dad. I can happily report that this young one and its two siblings are still alive 3 weeks after fledging and are just about ready for full independence!


2 Responses

  1. John

    One of your best postings; the sequence of photos is great! Despite the hard work, I sense you are having another great summer.

    June 3, 2013 at 8:26 am

  2. Dad

    Wow, great series of photos! :-)

    May 31, 2013 at 6:17 pm