Thanks somewhat to Nancy’s helping hand but largely to their parents (who seem to have found 2 chicks easier to provide for than 4), the two Purple Martin chicks continue to….well, not thrive but….get by.
Here’s the history to date:
July 21st: when the nest was checked, one of the four had died of starvation and the other three were not doing well, one was an especially bad way.
#373 – 41.7 g.
#374 – 42.6 g.
#375 – 28.2 g.
We decided to remove the lightest two and feed them and leave the heaviest bird in the nest to see what would happen. The two birds were fed about every half hour. It was found that playing a recording of adult calls would elicit feeding behaviour from the young birds; i.e., stretching out the neck and opening the mouth. It was also noticed that while the lightest bird performed these behaviours, he was much less energetic in doing so.
The birds were weighed at around 1330 (24 hours after yesterday’s weigh-in).
#373 – 41.55 g.
#374 – 41.95 g.
#375 – 28.45 g.
As #374 had lost weight we decided to remove it as well and provide supplemental feeding.
The birds were weighed at 1300.
#373 – 42.55 g.
#374 – 42.60 g.
#375 – 27.3 g. (this was concerning; it subsequently died during the night)
The two remaining birds were weighed in the morning (0730); both had lost weight but this is a regular pattern seen in small birds: they gain weight during the day and lose it during the night when they can’t feed – the key is to get enough resources during the day to sustain them through the night.
#373 – 37.15 g.
#374 – 40.40 g.
We decided that if these birds were going to have any sort of chance to fledge we would have to return them to their nest and have the parents resume feeding them. We weren’t sure if this was going to happen and were pleasantly surprised when the adults “rediscovered” their young and began to make semi-regular feeding trips to the nest. The young were quite responsive, sitting at the opening to the nest box with mouths agape at every passerby.
July 25th: weighed at 1030.
#373 – 38.10 g.
#373 – 41.45 g.
July 26th: weighed at 1730.
#373 – 45.15 g.
#374 – 50.35 g.
This represented a significant weight gain for these two youngsters.
We weighed the young birds twice today; you will see the fluctuation that they go through during the course of a day.
#373 – 42.30 g.
#374 – 45.75 g.
#373 – 47.35 g.
#374 – 53.80 g.
At the time of the second weighing Nancy noticed that the nest was infested with blowfly larvae (slug-looking things that attach themselves to the young birds and suck their blood) and feather mites. Both take an energetic toll on the well-being of the birds so we decided to change the nesting material. The old nest was discarded and Nancy put in a mixture of grass clippings and wood ships.
The considerable weight gain they experienced during the day would stand them in good stead through the night. We experienced a lengthy thunderstorm with strong north winds (blowing right into their nest box), heavy rain, and a drop in temperature. So I wasn’t sure what we would find when we went to weigh them this morning @ 0930.
#373 – 43.40 g.
#374 – 46.10 g.
They had lost weight from the previous day but still weighed more than they had the previous morning. Further, there was no sign of any parasites.
It will still be touch and go for the next couple of weeks but….if they can continue to put on weight and the weather stays relatively benign and their parents don’t desert them (and continue to provision them) then they have a good chance of fledging. I wonder if we’ll see them next year.