Nesting 2

Photo credit: Jon Moran

With spring, the garden is stirring and our fingers are itching to tend to its needs. What can we do in our gardens that would help the mother hummingbirds feed their chicks?

Hummingbird females lay two eggs, one at a time and usually within 24 hours of each other. It is truly astonishing to think that each of these eggs can weigh more than a quarter of her body weight! At this time, the female is incredibly busy finding food because making eggs requires an enormous input of resources that must come from her environment. In addition to the fats and protein needed to make the yolk and egg white, a lot of calcium is required, especially to build the protective shell. 

As you watch your female hummingbird’s activities more closely, you may see some rather odd things. Perhaps you have seen her at your feeder with a black smudge on her belly or more surprisingly, you noticed her poking her bill into a pile of ash. It turns out that wood ash is a fabulous calcium source, in fact, 50 – 75% of it is calcium oxide! Alternatively, you might spy a female working along a paving stone or grout – she is finding calcium (and possibly the odd insect) in our human-built environment.

This female Calliope Hummingbird has a rather dirty throat after a collecting calcium from an ash pile.  Photo credit : Sue Elwell

Once the eggs have hatched, the mother hummingbird must turn her attention to feeding her young chicks. When the nestlings sense that their mother is returning from a foraging trip, they stand up and open their mouths, exposing a bright yellow gape. This strong ‘feed me!’ signal encourages the mother to regurgitate prey items from her crop. The crop is a thin-walled sac located at the top of the digestive tract where meal items can be stored. As she feeds her chicks, it often looks as if the female is plunging her dagger-like bill into a tiny throat. While she does bob downward, the young also lurch upward toward the food. The food is then transferred into their crop. From there, they can squeeze small amounts of food into their main digestive tract.

Watch a Rufous Hummingbird feed her chicks – video

A mother hummingbird provides her chicks with a truly eclectic diet. She may hover in a cloud of small flies, gently picking out one tender morsel after another or she may work along a branch or leaf, plucking insects from the surface. The insects and spiders that she gathers provide the proteins, fats and minerals that are the building blocks for growing bodies. 

One of RBPO’s research projects was on the diet of nesting Rufus hummingbirds. It involved collecting and analyzing the DNA in faeces decorating the area around empty nests. (To avoid disturbance, our samples were taken after the chicks had fledged successfully). If you follow the red arrow on the photo, it points to a dropping ejected outside the nest, typical of what would have been studied. We found that nestlings were fed soft bodied food items and most of these were flying insects that spend their early life stages in wet environments, only emerging from the water as adults.

As the chicks grow, they require more and more food. Just as human teenagers become bottomless eating machines, a chick’s food requirements increase as it nears fledging. This prodigious appetite is necessary as nestlings must reach full size before they can leave the nest. To meet the ever-increasing demands of her young, the mother hummingbird’s foraging time also increases and will dominate her daylight hours as the chicks reach fledging. 

The chick’s yellow (‘feed me’) gape will disappear within ten days of leaving the nest. By then, they are expected to find food on their own. The fledglings may peep quite stridently to get her attention, but with their increasing independence, their mother no longer needs to spend all her time finding them food. Even though she is not necessarily still feeding them, you may see the fledglings following their mother around as they learn about the world. 

 

We can help hummingbird chicks grow into strong, healthy adults by providing nutritious and abundant food sources. A ready supply of tiny insects depends on access to water and plants that are free of poisons.  

As you know, insecticides can kill the insects that hummingbirds need to eat. Hummingbirds may be exposed to insecticides in nectar and when they eat insects from contaminated plants or water. If insecticides are used in our gardens directly or introduced through pre-coated seeds, pesticide-treated plants or added to the water, they are affecting hummingbirds, the insects, and other wildlife too.

By encouraging native plants and animals, we will help hummingbirds and other wildlife feed well and thrive. What a pleasure to know that by creating a safer, nutritious garden, we have helped female hummingbirds raise healthy fledglings, putting them on the path to success.

Back to Conservation Action Series Main Page