{"id":2944,"date":"2025-03-05T12:44:15","date_gmt":"2025-03-05T20:44:15","guid":{"rendered":"https:\/\/blogs.oregonstate.edu\/gardenecologylab\/?p=2944"},"modified":"2025-08-06T12:52:34","modified_gmt":"2025-08-06T19:52:34","slug":"ecological-traps-in-gardens","status":"publish","type":"post","link":"https:\/\/blogs.oregonstate.edu\/gardenecologylab\/2025\/03\/05\/ecological-traps-in-gardens\/","title":{"rendered":"Garden Science: Reducing Ecological Traps in Gardens"},"content":{"rendered":"\n

This post was originally written for the Hardy Plant Society of Oregon (HPSO) Quarterly<\/a> magazine and was greatly improved by the HPSO editorial team.<\/p>\n\n\n\n

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Part of the joy of gardening is seeing the beautiful birds, butterflies, and other charismatic fauna that come to visit your space. With careful thought about the elements that draw them into your garden, you can make relatively minor adjustments that help promote their survival and conservation.<\/p>\n\n\n\n

Many features of garden spaces are attractive to insects, birds, and other types of urban wildlife. For example, as the profusion of flowers increases in garden spaces, beneficial insect species also increase. Birdfeeders provide ample and easy-to-access forage for a variety of wildlife, including birds and squirrels. Water features such as ponds or fountains are exploited by honey bees and other garden wildlife, particularly on hot days.<\/p>\n\n\n\n

For many animals, these features of gardens represent relatively novel cues that they use to assess the overall quality of foraging or nesting sites. Sometimes animals make bad decisions on novel cues encountered in human-dominated landscapes. Because of the way that light reflects off of and is polarized by shiny, dark objects, mayflies and dragonflies are more attracted to oil spills, asphalt roads, and dark green automobiles than to water.1<\/a><\/sup> These insects often become trapped in oil puddles or stuck to the road, and any eggs laid on these surfaces will obviously not survive.<\/p>\n\n\n\n

When organisms choose to nest, feed, or reproduce in a highly attractive but low-quality habitat, that habitat is known as an \u201cecological trap.\u201d Two criteria determine an ecological trap: First, an individual prefers a poorer habitat over a better habitat; and second, the individual\u2019s survival or reproduction is lower in the preferred habitat. Intuitively, it is easy to understand why gardeners who use pesticides on flowering plants that are highly attractive to insects are at high risk of creating ecological traps. But there are other, less obvious, ways that well-meaning gardeners may attract beneficial species into garden spaces only to ultimately harm the chances of survival and successful reproduction. In this article, I review what we do know about ecological traps in garden spaces, and share ideas for how to reduce or eliminate them.<\/p>\n\n\n\n

Sometimes innocuous and every day actions conspire to create an ecological trap. For example, porch or other outdoor lights act as an ecological trap for many night-flying insects. These will continuously turn their bodies so sources of light shine on their backs. Scientists think this is an adaptation to help them maintain a constant flight path that is oriented to the horizon.2<\/a><\/sup> However, the prevalence of artificial lights makes this a maladaptive behavior that causes them to fly erratically and also makes them more prone to being eaten by spiders that build webs near night lights.3<\/a><\/sup> One relatively easy way to limit the negative effects of artificial light on night-flying moths and other insects is to switch to yellow-colored light bulbs. Flight behavior is suppressed in moths when exposed to yellow light, making them less likely to gather at your porch light than if it were a white bulb.4<\/a><\/sup><\/p>\n\n\n\n

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Rooftop gardens are wonderful amenities for people, but on the fifth floor or higher, you may want to avoid plants that are highly attractive to pollinators. Photo source: Greg P Griffin on Flickr (CC BY 2.0). Image URL https:\/\/www.flickr.com\/photos\/17530093@N08\/9316854571\/<\/a><\/figcaption><\/figure>\n\n\n\n

A second item to consider is where your flowering plants are located, particularly those that are highly attractive to insects. There is some evidence that pollinator gardens on rooftops or high balconies (fifth floor or higher) might function as ecological traps by drawing insects in with flowers to a largely isolated habitat subject to environmental conditions harsher than those at ground level.5<\/a><\/sup> This suggests that gardeners should avoid planting highly attractive flowers on high balconies or rooftop gardens of mid- and high-rise buildings. Recent evidence also suggests that high floral abundance adjacent to streets with heavy traffic increases mortality of butterflies and dragonflies.6<\/a><\/sup> This study was conducted near high-speed freeways but nonetheless provides a cautionary note to gardeners with landscaped areas adjacent to heavy traffic.<\/p>\n\n\n\n

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Roadside flower gardens are beautiful, but can pose a hazard to butterflies and dragonflies. Source: Jonathan Cutrer<\/a> on Flickr (CC BY-2.0). Image URL: https:\/\/www.flickr.com\/photos\/joncutrer\/40632659923<\/a><\/figcaption><\/figure>\n\n\n\n

Most research on ecological traps in urban spaces has focused on birds7<\/sup> <\/a>and has found that the propensity of a garden to act as an ecological trap is variable across different contexts. For example, gardeners who live adjacent to woodland habitat have greater on-site bird mortality due to domestic cats.8<\/a><\/sup> This suggests that if you live near forest land or another wooded site, you may want to think twice before putting out bird feeders. Even if you don\u2019t have an outdoor cat, they\u2019re such ubiquitous characters in urban areas that drawing birds in with a bird feeder may be doing more harm than good. Similarly, bird feeders concentrate foraging birds at a specific site, which also attracts predators looking for prey. Although squirrels are the most common non-target animal seen at bird feeders, carnivorous foxes, skunks, racoons, and coyotes increase locally when bird feeders are present.9<\/a><\/sup> This is why it is important to place feeders in a spot that provides birds with easy retreat to a nearby tree or tall shrub, where they can escape potential predators.<\/p>\n\n\n\n

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Careful consideration of where you place your bird feeder can help protect avifauna, such as this yellow rumped warbler. Photo source: ajdemma on Flickr (CC BY-NC 2.0). URL https:\/\/www.flickr.com\/photos\/ajdemma\/12198584056\/in\/dateposted\/<\/a><\/figcaption><\/figure>\n\n\n\n

By thinking carefully about the cues in your garden that attract birds, butterflies, and other welcome fauna, you can avoid dangers to them, encourage their survival, and add to the joy your garden brings you.<\/p>\n\n\n\n

Gail Langellotto is a professor of horticulture at Oregon State University and Principal Investigator of the Oregon State University Garden Ecology Lab. She holds a B.S. in biology and an M.S. and Ph.D. in entomology, all from the University of Maryland<\/em>. She is a regular contributor to the<\/em> HPSO<\/em> Quarterly<\/em>.<\/p>\n\n\n\n

References<\/strong><\/p>\n\n\n\n

1<\/sup>Horv\u00e1th et al. 2009. Polarized light pollution: a new kind of ecological photopollution<\/a>. Frontiers in Ecology and the Environment<\/em>,7: 317\u201325.<\/p>\n\n\n\n

2<\/sup>Fabian et al. 2024. Why flying insects gather at artificial light<\/a>. Nature Communications<\/em>,\u00a015(689): 15pp.<\/p>\n\n\n\n

3<\/sup>McMunn et al. 2019. Artificial light increases local predator abundance, predation rates, and herbivory<\/a>.\u00a0Environmental Entomology<\/em>,\u00a048: 1331-1339.<\/p>\n\n\n\n

4<\/sup>Shimoda, M., &\u00a0Honda, K.-I.\u00a02013.\u00a0Insect reactions to light and its applications to pest management<\/a>.\u00a0Applied Entomology and Zoology<\/em>,\u00a048:\u00a0413\u2013421.<\/p>\n\n\n\n

5<\/sup>MacIvor JS. 2016. Building height matters: Nesting activity of bees and wasps on vegetated roofs<\/a>. Israel Journal of Ecology and Evolution<\/em>, 62: 88\u201396.<\/p>\n\n\n\n

6<\/sup>Keilsohn et al. 2018. Roadside habitat impacts insect traffic mortality<\/a>. Journal of Insect Conservation,<\/em> 22: 183-188.<\/p>\n\n\n\n

7<\/sup>Zu\u00f1iga-Palacios et al. 2021. What do we know (and need to know) about the role of urban habitats as ecological traps? Systemic review and meta-analysis<\/a>. Science of the Total Environment<\/em>,780: 146559.<\/p>\n\n\n\n

8<\/sup>Shipley et al. 2013. Residential edges as ecological traps: postfledging survival of a ground-nesting passerine in a forested urban park<\/a>. Auk<\/em>, 130: 501-511.<\/p>\n\n\n\n

9<\/sup>Reed and Bonter. 2018. Supplementing non-target taxa: bird feeding alters the local distribution of mammals<\/a>. Ecological Applications<\/em>, 28:761-770.<\/p>\n","protected":false},"excerpt":{"rendered":"

This post was originally written for the Hardy Plant Society of Oregon (HPSO) Quarterly magazine and was greatly improved by the HPSO editorial team. Part of the joy of gardening is seeing the beautiful birds, butterflies, and other charismatic fauna that come to visit your space. With careful thought about the elements that draw them […]<\/p>\n","protected":false},"author":502,"featured_media":2946,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[1295237],"tags":[1295366,1295369,1295368,1295367,1295365],"class_list":["post-2944","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-garden-design","tag-artificial-light","tag-birdfeeders","tag-cats-in-gardens","tag-roadside-flowers","tag-wildlife-friendly-garden","has-thumbnail"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"https:\/\/osu-wams-blogs-uploads.s3.amazonaws.com\/blogs.dir\/2786\/files\/2025\/03\/40632659923_cc751917a3_o-scaled.jpg","jetpack_sharing_enabled":true,"post_mailing_queue_ids":[],"_links":{"self":[{"href":"https:\/\/blogs.oregonstate.edu\/gardenecologylab\/wp-json\/wp\/v2\/posts\/2944","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blogs.oregonstate.edu\/gardenecologylab\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blogs.oregonstate.edu\/gardenecologylab\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blogs.oregonstate.edu\/gardenecologylab\/wp-json\/wp\/v2\/users\/502"}],"replies":[{"embeddable":true,"href":"https:\/\/blogs.oregonstate.edu\/gardenecologylab\/wp-json\/wp\/v2\/comments?post=2944"}],"version-history":[{"count":1,"href":"https:\/\/blogs.oregonstate.edu\/gardenecologylab\/wp-json\/wp\/v2\/posts\/2944\/revisions"}],"predecessor-version":[{"id":2949,"href":"https:\/\/blogs.oregonstate.edu\/gardenecologylab\/wp-json\/wp\/v2\/posts\/2944\/revisions\/2949"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/blogs.oregonstate.edu\/gardenecologylab\/wp-json\/wp\/v2\/media\/2946"}],"wp:attachment":[{"href":"https:\/\/blogs.oregonstate.edu\/gardenecologylab\/wp-json\/wp\/v2\/media?parent=2944"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blogs.oregonstate.edu\/gardenecologylab\/wp-json\/wp\/v2\/categories?post=2944"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blogs.oregonstate.edu\/gardenecologylab\/wp-json\/wp\/v2\/tags?post=2944"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}