Sunday, May 3, 2020

The carnage begins

Nests are hatching already in spite of the cold and wet spring.  Interestingly, by far the greatest percentage of nest with nestlings is in Westmoreland Park.  Next is Reed campus.

But that's where the carnage is happening.  Alas, we may be following the same pattern I observed last year when the percentage of nests lost at Reed due to predation was about 80%.  In comparison, Oaks Bottom and Westmoreland nests were relatively safe at 12% losses. In 2018, Reed also lost few nests at 11%.

So what's up with Reed?  Well, my working hypothesis is that crows, being exceptionally smart and opportunistic, figured out that bushtit nests are lovely little parcels of protein and cue in on them just as they hatch and activity increases as the parents go to and fro with food for the kids.  In 2018, they were relatively clueless. It was last year that some individual crows figured it out.  I was hoping they would have forgotten.  But, so far, it appears they may have long memories.

Of course crows are not the only predators on bushtit nests.  All the corvids (jays, crows, and ravens) as well as squirrels and other mammals that can climb trees are happy to enjoy a meal of baby bushtits.  Owls may also pick off nests at night.

So it may be that Reed has a habitat that encourages populations of other predators besides crows.  But that doesn't explain the difference between 2018 and 2019, does it?   Only a predator that has learned about the delectability of bushtit nests would explain that.

My money is on the crows.

Regardless of the perpetrators, Reed campus is a frustration as nests that were lovely and easy to watch and reach eventually to band babies at are found torn and useless.  In every other way, Reed campus is the ideal study area this year.  Because of the current pandemic, there are few students and visitors on campus.  Campus security is out in force.  I can walk around, for the most part, without a mask.  It's really an ideal research site in these unusual times.  The rest of my study areas are crawling with people on nice days.  And, since nice days are unpredictable, I can't depend on being able to be out safely.  This is particularly true of Oak Bluff trail where joggers and walkers are impossible to distance from.  Consequently, those nests (and there are plenty!) have become very low priority.  This is extremely sad because that's the most "natural" area I have and I have always enjoyed my interactions with the people I meet there.

Oh well. This too shall pass.  In the meantime, we are doing the best with what we have and are keeping our fingers crossed that a few Reed nests survive the season.  

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