Monday, April 30, 2018

Are You Watching a Hummingbird Nest?

Allen's hummingbird female
It is the last day of April and we have four active Allen's hummingbird nests in our yard. (Selasphorus sasin)

Two nests have eggs. 

Allen's hum nest in butterfly bush

Allen's hum nest high in Catalina cherry
One is in an ornamental butterfly bush (Buddleja). This nest is awfully low to the ground and poorly covered by vegetation. It is not a good location and the female will need good fortune to be successful. Her chicks may be vulnerable if summer temperatures over 100 degrees come early.

The other is high in a native Catalina cherry shrub (Prunus illcifolia). This is an excellent location.

Allen's hum chicks, 10-15 days old
'Fairy Tree' nest with hum chicks
Two of the nests have chicks. The 'Fairy Tree' nest has already seen two chicks fledge in March. The female rebuilt the nest and these two should fledge toward the end of May. 

This mother is experienced and has used this Catalina cherry as a successful location in the past.

Allen's hum nest in toyon

The fourth nest is in a native toyon.  (Are you seeing a pattern? Native shrubs are more likely to house successful hummingbird nests.)

Native plants not only provide native insects as food, they also grow at a rate similar to the growth of the chicks. Nests in fast growing ornamental plants sometimes are torn apart by the growing plant. The chicks can become homeless before they are ready to fly.

These two chicks, yes there are two tucked in close together, should fledge soon.

These four mother Allen's hummingbirds are busy. This is the second nest of the year for each of them. Two were successful the first time and two were not.

So far in 2018 that's eight Allen's hummingbird nests in our yard. I monitor my hummingbird nests for NestWatch, part of Cornell University's Citizen Science bird data program. To date, my Allen's hummingbirds are the only nests where data has been collected on the reproduction of this species in 2018. 

I know there are more of you out there watching hummingbird nests. NestWatch needs your data. Successes and failures are equally important. This year we had eggs that shriveled and a chick that died when the weather turned from unusually warm back to cold winter weather. 

Early nesting attempts can lead to failure. This is the insidious impact of warming winter temperatures. Plants and animals take signals from the weather to begin reproduction. Record warm temperatures in January can lead to chick deaths when February brings a return to cold weather and rain.

How do I spot the nests? I watch the females:
  • Females gathering nesting materials will fly right back to their building locations. I put out natural nesting materials.
  • Females sitting in one place with their beak angled down and making an up-and-down movement with their head are most likely nest building or feeding chicks.
  • Females catching small flying insects are typically craving protein because they are about to lay or have laid eggs or are gathering protein for newly hatched chicks. Watch where they go. 
  • When eggs or chicks are present females typically do not fly directly to a nest. They fly to the home bush or tree, then make several short movements approaching the nest.
Several friends, especially those on the Pacific Coast hummingbird migratory path, have told me they are seeing far fewer hummingbirds. Data will help figure out if these birds have changed their migratory path or if their numbers are declining.

Join me.  Collect data on your hummingbirds for eBird and NestWatch. The greater the data, the better the science. 

What to do with a baby bird? 


Jim said...

Thank you for the link to nestwatch. I signed up.

A hummingbird buzzed me in front of my face as I went out into
the patio. "There must be a nest nearby", I thought. I looked around the
shrubbery, but I didn't see a nest. From indoors a few minutes later, we
spotted the beginnings of a nest in our potted bamboo plant.

The next few days we observed nest-building...
- It is a female Allen's hummingbird
- She brought nest materials: fluffy seeds, plastic foam, spiderweb
- She repeatedly wove spiderweb around the materials and the bamboo
- She decorated the nest with colored items (as camoflage)
green bits of plastic ribbon
white paper or paint flecks
- She shaped the nest with her feet

Keri Dearborn said...

Thanks, Jim for your observation. I encourage you to enter your nest on the NestWatch website. Allen's hummingbird need your data. Jim is absolutely right. It is amazing to watch these little birds with teeny feet stomping down the center of their nest to get the shape just right.