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Is it berries or insects?

Posted by esh_ga z7 GA (My Page) on
Thu, Jan 10, 08 at 22:26

For birds, it's both actually. As a food source, that is.

I just finished reading a very interesting book called "Bringing Nature Home" by Douglas Tallamy who is a Professor of Entomology.

So many people focus on planting berry producing plants "for the birds". Actually, birds eat a lot of INSECTS. And when it comes time to feeding their young, they are feeding them insects (and spiders).

So the premise of this book is to plant a wide variety of native plants to attract a variety of native insects for the birds to feast on. Berries are good too ... it is just that they are not the primary source of food for birds over the course of a year.

He explained that non-native plants are not so attractive to native insects so they will not be drawn to eat them. Many insects are specialists (eat only certain things), although there are generalists (think of Japanese Beetles which eat so many different plants). The specialists are geared to only eat certain plants, so planting crepe myrtle and nandina and other non-natives will not attract them. While you might think that is good (fewer pests), if you are trying to attract birds, you have lessened your chances.

Non-native plants therefore reduce the diversity of the whole food chain by reducing the source of food for the first guy in the chain: the insect herbivores.

He also pointed out that a damaging by-product of importing non-natives is the parade of pests (Japanese beetle, hemlock adelgid) and diseases (the fungus that killed the chestnuts, the Sudden Oak Death pathogen that affects more than just oaks) that have unknowingly come over with the plants.

It's a very good book, has lots of facts, references and tables to back up what he's saying. He and his students are currently performing even more studies on non-native plants and the ability/willingness of native insects to eat them.

By the way, the number one plant family in terms of nourishing a wide variety of insect herbivores in the US? The oaks (Quercus family). They support 517 different insect herbivores. By contrast, the invasive Melaleuca tree (a problem in Florida), supports just 8 insect herbivores in this country. But in it's native habitat, it supports 409. After 150 years in this country, our insects are by and large not interested in it. This plant has taken over thousands of acres from native vegetation and has obviously contributed very little to the biodiversity of the area in return. In fact, I'd say it has lessened the biodiversity.

Here is a link that might be useful: Link to book on amazon

Follow-Up Postings:

RE: Is it berries or insects?

I also just got done reading "Bringing Nature Home". I found it very interesting also. It seems a very good thing to plant more native species to support the insects and birds. I do wonder though about the larger picture. It seems that increasing communication and travel and increased sharing of everything including all kinds of plants is the way things are going. I cannot imagine that the trend will stop or change any time soon if ever. Also how does it all fit with the darwinian "survival of the fittest? theory? I'm just left with a kind of large question mark in my mind about the whole issue. It just doesn't seem realistic to think we won't import all kinds of new plants etc even though it might upset the ecological balance. Every new introduction comes with positives and also negatives and it is just so hard to judge ahead of time what they all will be.

RE: Is it berries or insects?

I agree that it is not realistic that things won't still be imported. There are people that live for the challenge of discovering new plants and bringing them back to other parts of the world ... and people that crave having the "newest" thing in their garden. Problems aren't always apparent ... even in the first few years after introduction (except maybe for kudzu - which has an amazing grape soda fragrance, btw). I know that collectors and importers don't knowingly bring in pests and diseases, but the risk is there.

To me, the "survival of the fittest" concept doesn't quite apply because it is not nature that has brought these things together ... it was man. Our actions are causing things to "not survive". We have destroyed habitat - it's hard to compete with large machinery. We have brought in pests that these organisms might never have been exposed to. They don't have time to adapt to them.

The conclusion of this book is that people should not stop trying to help restore things, even if it is just on a small plot. Plant native plants when and where you can, if enough of us do it, it makes a difference. Don't think you can't make a difference.

RE: Is it berries or insects?

Dear Esh,
I agree with you except for one point. We humans are certainly part of nature so darwinian theory does apply here. We are just another species of animal really, although we sure do a lot of harm but then we also do good!

RE: Is it berries or insects?

Esh, Amen. Sounds like a great book. I wish more people understood this concept.

RE: Is it berries or insects?

This book sounds fantastic. As I have become more involved with restoring native plants, creating a wildlife habitat, and learning about birds in particular, I realized that the primary food source for most birds in Spring-Summer-Fall is insects. Beneficial insects serve important purposes in the garden too.

Most people are enchanted with birds and butterflies, but do they realize the chemicals they are dumping on their lawn or gardens are killing important food sources for birds and well as killing the birds and pollinators themselves??

Using native plants, gardening organically, and also creating natural or wild areas are critical. I let leaf litter, sticks and branches, and dead trees alone. I am planning to increase wild areas of native grasses and forbs. I have brush piles, and plan to grow many native vines. The thickets of vines, dead branches, and dense shrubbery in my yard are some of the most attractive areas for the birds. Not in the front yard, that is more cultivated(still full of native plants as well as non-natives, and leaves, compost, and pine straw for mulch). Most of this is in the large back yard.

Some people think an overgrown area is messy-looking. To me, it is beautiful. It is the monocultures of chemical lawns, the overly manicured green meatball shrubs, and obsessively tidy gardens of non-native plants that look - well, not so beautiful.

RE: Is it berries or insects?

To follow a bit on the last of what terrene said: Down here in the South, chinese privet is the #1 invader of roadsides. Sure kudzu is more obvious ... but privet covers the most acres. Unfortunately it is so ubiquitous ("Being or seeming to be everywhere"), that many folk have come to think of it as "native".

It makes a mess of the roadside, often becoming an impromptu trellis for vines until the whole area looks messy and overgrown. And THIS is the look that some people (perhaps even many people) associate with "native plantings". Ugh.

It's no wonder that people shy away from using natives based on this perception. But hopefully learning more about the whole process (from plant to insect to bird ...) will help people realize it is something worthwhile doing and give them a sense of purpose in their garden.

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