I saw a hummingbird recently and wondered which plants they could be feeding from right now (mid-May; I’m in the US, NY state). Today I saw one visiting an invasive honeysuckle (Lonicera morrowii), which I found interesting. These are prolific in my area and much of the northeast US. I’m curious if this species or other invasives are a major food source for hummingbirds.
Thinking on this brings me to a larger question- which native birds and insects make use of the the many invasive plant species of the US northeast? Can anyone recommend a resource on this topic?
[Note- I’m not suggesting we encourage invasive plant species, I’m just curious about the effects they’re having.]
I’m not so sure, but my guess would be that the hummingbird didn’t really have a preference and just chose to feed on Lonicera simply because it provided the most reliable source of nourishment? Furthermore, if these plants are more abundant, invasive or not, then its also more likely that they would come across it than not.
I also recall a clip from a David Attenborough documentary about a hummingbird whose beak is so long that only it can feed on a certain flower whose nectar is hidden very deep, ie. has a flower niche, but I don’t know how common that trait is.
I live in invasive country in one of the oldest “settled” towns (the earliest invaders of the human type) and I have a ton of stuff I haven’t been able to outpace. Lamium flowers, honeysuckles (planted a while ago by the previous owner over a large swath) get a lot of Ruby-throated hummer attention. Unfortunately, cedar waxwings, and other fruit eaters spread the honeysuckle if I can’t lop off the flowers in time. Bittersweet is another one that’s a challenge to remove and is very popular with fruit eating birds in the colder months. In my neck of the woods, I’ve observed many syrphidae and hymenoptera on taraxacum and a slew of arthropods utilizing the many invasive "weedy"species like: St.john’s wort, bladder campion, cresses, ground-ivy, daucus (especially flower longhorn beetles) in a variety of ways. I’ve seen xysticus use an invasive primrose to keep her eggs. Japanese Stilt grass is a popular nesting material of choice for a variety of cup nest builders (I haven’t found any in cavities yet and you asked about feeding not nests!!!) I’m sure I’m missing stuff but this is to say that yes, not only feeding but a variety of behaviors can be observed between invaders and natives. Informally, I’m keeping track of which predatory arthropods will take marmorated stink bugs. List is growing!
I too recall that though I think it is only one or a few species that are so highly specialized as to need a specific flower source. I think the part about abundance and availability is spot on too. Many organisms are quite adaptive and persist despite a lack of preferred or ideal resources. Behaviors in a particular location may not indicate a broader trend of a specific preference.
I’m in NE PA and work on invasive species in PA and NY. Last year we noticed both chipmunks and birds eating the berries of mile-a-minute vine. There was a random patch that started growing on the PA side of the Delaware River across from a NY site where we’ve been working on eradicating the vine, but I wasn’t sure if the berries were edible…now I know and expect it is going to be a harder to control than I’d hoped.
Welcome to the forum, @jessica32! The ecology of the Delaware is fascinating. So much water travel by humans between the states and various habitats and a major resource for wildlife leads to a lot of spreading I imagine. Do you have an idea of what might utilize knotweed for forage?
As part of my PhD research, I compared arthropod food webs in native and non-native plant communities in the Mid-Atlantic region of the US (parts of DE, MD, PA, and NY) and documented host plant associations. I’m hopeful that this summer, I can spend some time actually getting the manuscripts published in a scientific journal, but what I can say it this for the following nonnative plants I did study:
Plant-feeding insects who were feeding on non-native plant hosts were either generalist feeders that avoided chemical plant defenses in the tissues (such as many of our plant-sucking Hemipterans) or plant-feeders that fed on related host plants (i.e., Norway maple was fed on by insects that feed on native species of maple).
The majority of insects I did collect on non-native plants were non-native themselves, and shared their native range with the host plant (i.e., European plant hosts had European insects, and Asiatic plant hosts had Asiatic insects, etc.).
None of this is “news”, but it does highlight some of the impacts non-native plants can do in the environment, notably by homogenizing the diversity of the food web to other non-natives or those few that recognize the host plant as a similar species (but may not fare as well as they would with their native host counterparts).
I recall reading that Ailanthus Webworm Moths were able to jump from Ailanthus as a host to Tree of Heaven, which is invasive. That led to a massive range increase on the part of the moth.
Hudsonia has collected a large amount of data on fauna that use Japanese knotweed, but I don’t believe its been published yet. I volunteered with them some years ago and was able to look over the data. From what I recall, the primary relations are bees and flower flies visiting the flowers, snails and spiders living inside the hollow stems, and a minor amount of herbivory of beetles maybe? or caterpillars? (I can’t recall exactly.)
Might this make for an interesting iNat project? I was watching a white-tailed deer eat dandelion seed heads the other day and thought that it might be neat to keep track of examples of native species interacting with invasives in a given geographical region. Perhaps there’s potential for either discovering biological control methods of invasives or, on the flip side, documenting ways by which invasives spread. Thoughts?
Thank you for this reply- these ideas will help me think on this some more. I’m glad to hear you’re doing this work, and I’d love to read your paper when it becomes available. Does your work focus on herbivorous arthropods, or have you looked at pollinators, as well? I suppose I’m wondering about the impact of common insect-pollinated invasives like multiflora rose, wineberry, autumn olive, the honeysuckles, garlic mustard, etc…
I’ve been aware that invasive plants (like many non-invasive, but non-native garden plants) do not serve as host plants for our native herbivorous insects, and so decrease overall biodiversity of a habitat by out-competing the native plants that feed many native insects. I’d worked in horticulture for several years before I encountered this idea (by Doug Tallamy’s Bringing Nature Home, of course), and it really blew my mind at the time. Lately I’ve been tuning in to pollinators and wondering what plants they make their living on throughout the year. As you’ve seen in the northeast, 20th century invasives and the colonial European imports make up a large percentage of lawns and understory.
Also, I’m curious - how do the generalist feeders avoid the plant’s chemical defenses?
A big reason behind the huge range expansion of Anna’s hummingbird in the Western US is the presence of non-native plants that bloom when native plants aren’t in season, particularly Eucalyptus and tree tobacco.
I observed two species feeding on flowers of Japanese knotweed during my research in NY: common pug (Eupithecia miserulata) and camouflaged looper (Synchlora frondaria). Both of these species are considered to have very generalized diets and were feeding in the floral tissues. We encountered caterpillars from other families exhibiting incidental feeding (“taste-testing”) on knotweed leaves, but I wouldn’t be surprised if caterpillars that feed on smartweeds could make the jump at some point.
I conducted research looking at herbivores, detritivores, pollinators, and predators. We investigated several species of dominant, non-native plants in the Mid-Atlantic (amur honeysuckle, porcelainberry, autumn olive, callery pear, Japanese knotweed, Japanese stiltgrass, multiflora rose, norway maple, orchardgrass, Queen Anne’s lace, and wineberry). If there’s specific questions you have for these species or their impacts on arthropods, let me know and I can try to answer to the best of my ability.
There have been studies looking at how pollinators respond to non-native host plants, and in general, when native plants are displaced by non-native plants in the landscape, you lose the specialists associated with them. So non-native plants that have abundant floral resources like Japanese honeysuckle, for example, may benefit generalist pollinators at the cost of losing the specialists in the environment. It’s also been shown that non-native pollinators benefit from non-native plant hosts in the landscape too–honey bees do well with non-natives from their own range–and this can lead to further difficulties with conserving native pollinators.
Also, in response to how herbivores could avoid plant defenses, some secondary plant compounds are stored in the vacuoles of plant cells, which needs to be ruptured to release them, such as when a caterpillar chews on a leaf. If you have piercing-sucking mouthparts like an aphid, for example, you can sometimes circumvent those defenses by eating around them or avoiding those plant cells entirely and going for the vascular tissues.
Wow- thank you, Calosoma. I may have specific questions for you as I poke into this more. As a person with a plant background, I need to spend time learning more about the insects.
Out of curiosity, did you find any herbivores feeding on Japanese stiltgrass?
And very interesting detail about the compounds being stored in the vacuoles- I hadn’t heard of that type of avoidance, but it makes sense.
I’ve found rustic sphinx larva (Manduca rustica) on Ligustrum sinense; and a snowberry clearwing larva on Lonicera japonica. Not enough to put a dent in the spread of the invasives unfortunately.
We found few species feeding on Microstegium during our study. We could only associate two grass-feeding planthoppers (Polyamia sp. and Delphacodes sp.) with the host plant; we collected other insects that likely fell from the canopy (as Microstegium tends dominate forests in eastern US).
My sense is that almost all bird species in the northeast US feed on non-natives in one way or another. I grew up there and thinking through the birds I saw regularly, there are none that feed on only one or few species, and so almost all will end up including in their diet non-native seeds, non-native nectar, non-native whatever sort of stuff they eat.