The insect eater’s challenge

Hummingbirds have a food problem. Insects are disappearing. Over this series, we have highlighted the importance of insects in the diet of hummingbirds. Insects are their key source of protein, fat and salts. When we ask ourselves how we can best help hummingbirds and other insect eaters, a vital component is ensuring that insects thrive.

In 2018, the International Union for the Conservation of Nature (IUCN) Red list raised the status of the Rufous Hummingbird from ’least concern’ to ‘near threatened’. This change was prompted by the global decline in insects. 96% of birds need insects in their diet. For some birds, like hummingbirds, these prey items are vital for daily function and reproduction.

How long since you last saw a bug splattered windshield?
Photo credit: Maigh

Unfortunately, human activities from draining wetlands to widespread insecticide use, have seriously reduced insect numbers. Landscapes, once insect-rich, have become food deserts for animals like hummingbirds, swallows and bats. You may have noticed changes to the Bug Splatter Index (also called the windshield effect). In the past, cleaning your car windshield regularly was just a necessary part of travel. Now, there is rarely a splotch to remove.

What insects do hummingbirds eat and how can we improve their availability? Our research has shown that hummingbirds consume an extensive variety of small, soft-bodied flying insects that, for the most part, have an aquatic life stage. This means that it is imperative to develop and retore wetland areas that support these insect-eaters’ food supply.

Urban water can be a wonderful resource for wildlife and humans alike if we are determined to use it well. In our gardens and local green spaces, we can make wet spaces where insects will thrive. To improve our municipal wetlands, it is important that our communities encourage their development and restoration. By learning more about the wildlife in our urban ecosystems, we can advocate for their needs. We can also share what we have learned with our friends and neighbours, so that we are part of developing community-wide understanding of wetland areas.

As taxpayers, we can advocate for wetlands in our municipalities. Currently, our municipalities have vast areas of impervious surface (e.g., roads, parking lots and rooves). Instead of slowing water and allowing it to percolate naturally into the soil, these surfaces collect water in such a way that flooding becomes a very real danger. Stormwater control removes water from our urban landscape. By adopting methods to slow and absorb stormwater, it can be harnessed to provide wetlands in our urban areas. Let’s make a concerted effort to encourage our municipal planners to include more water retention features like ponds, raingardens and bioswales.

In rural areas, there are slightly different processes at play. Actions need to be taken at many levels for the restoration of our river valleys. Between over drainage and excessive use of insecticides, many river valleys used for agriculture are no longer productive habitats for insect eaters.

Fraser Valley: Cheam Lake wetland is a productive habitat for insect eaters
Photo credit: a Moran

The issue of insecticides is a complex one, made more so because there are different types that are used in specific situations. Sometimes it is vital to use an insecticide, but targeted rather than indiscriminate use is important. You are probably familiar with a few types of insecticide, so let’s consider how two different types might affect hummingbirds and what your choices are about their use.

Firstly, let’s discuss Bacillus thuringiensis israelensis or Bti, as it is more commonly called. You may have encountered Bti as an anti-mosquito treatment for your pond. It is a natural strain of soil bacteria and it works by producing crystals that disrupt the guts of Diptera (true flies). When added to your pond water, the growing larvae die and do not emerge as adults.

At first glance, killing all true flies might seem like a good idea. But this agent is indiscriminately killing true flies, including the hummingbird’s favourite food, non-biting midges. Insect predators in the water, like fish and beetles, or those in the air, like hummingbirds and swallows, provide a natural insect control system. Unfortunately, killing all the true fly larvae in your pond means that their normal predators have no food and in turn, do not thrive. Undoubtedly, we have all enjoyed itchy repercussions when in the absence of natural predators, blooms of biting insects go unchecked.

Secondly, you are probably familiar with systemic insecticides, like the neonicotinoids and butenolides. You may have heard about these agents in relation to concerns about bee colony collapses. A recent 10-year review showed our use of systemic insecticides is causing enormous harm to birds, other animals and ecosystems as a whole through toxicity and loss of food resources for predators.

These insecticides are called ‘systemic’ because they flow in the plant sap. Anything that bites or sucks from the plant, including nectar drinkers, will be dosed with the insecticide. Hummingbirds visiting contaminated plants can be exposed by two routes – nectar and contaminated insect prey. You can ensure that the plants in your garden are safe for wildlife by only buying insecticide/pesticide free plants from the nursery and by selecting seeds that are not coated with insecticide.

In agricultural settings, only about 20% of the insecticide sprayed on plants ends up in the plant. The rest ends up in the soil and water, where it then enters plants beyond the original spay site. Since much of the flying prey consumed by hummingbirds have had an aquatic life stage, contaminated aquatic ecosystems can compromise insect productivity.

Fraser Valley: Bee hives near flowering blueberry bushes before insecticide spraying
Photo credit: A Moran

This is not to say that farmers shouldn’t ever use insecticides. Clearly, they can play a valuable role in maintaining productivity when there is a pest outbreak. However, it is not necessary to treat everything constantly, especially in the absence of a pest problem. Judicious insecticide usage, as promoted under an Integrated Pest Management program, is a middle ground that could reduce the environmental damage and allow our insectivores to thrive alongside crop productivity. By supporting farmers that use insecticides sparingly or not at all, we can encourage ecologically friendly farming practices.

We know that wetland restoration can be successful. Concerted efforts to restore wetlands along the migratory pathways of many ducks and geese has led to significant population recoveries. Let’s now turn our energies to the habitats of insect eaters. We can the trajectory of their populations too.

We can help hummingbirds and other insect eaters by encouraging insect biodiversity and productivity. We can actively promote healthy wetlands. This can be through personal actions, such as leaving our own ponds untreated, or by purchasing produce from farmers that use insecticides judiciously. It can also be through advocacy at your local level – such as promoting wetlands and raingardens in neighbourhood / municipal planning or by supporting organizations involved with restoring and maintaining healthy wetlands. Remember – as individuals, we can make a difference.

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