On 8/7/2015, I posted a Notes from the Field entry titled “Hummingbird Next (chapter 1)
”. The post featured an active ruby-throated hummingbird (Archilochus colubris
) nest located near Rocky River Nature Center
on West Channel Pond Loop Trail. The first week of August proved busy for the adult, as she was incubating 1-3 eggs without assistance from the male, long-since departed for Mexico or further south. The nest activity was monitored closely until something happened on or about August 10.
|The nest was observed without the adult female sitting atop. A storm with heavy rain may have spooked the dedicated mother-to-be. Abandoning the eggs for an extended period leaves them exposed and susceptible to predation or incubation-temperature fault. |
|A female ruby-throated hummingbird hovers at a wingbeat of nearly 60 times per second! She was feeding on glossy buckthorn (Frangula alnus) nearby the abandoned nest on August 21. Could this be our missing mother? |
Among birds, nest survival and success rates vary across species. Generally, the survival estimates are lower than you might have guessed. On average, fewer than half of all eggs laid reach adulthood. The ruby-throated hummingbird nest, nearby the nature center, did have a fighting chance. The odds for nestling survival were increased because the nest was placed in a mostly native forest high above the understory growth. Accordingly, nesting success is correlated to nest height, except in low-nesting species (e.g., veery (Catharus fuscescens
)) and other nest placement techniques. Next season will bring warmth and renewed opportunity to send their genes into the next generation, if the tenth-of-an-ounce hummingbirds can make it back from their 4,000 mile round-trip journey to the wintering grounds.