- January 7, 2016
Creating habitat and attracting pollinators to your garden can be a very rewarding endeavor, both for you and the wildlife you provide for. Butterflies and moths require nectar producing plants as a food source as well as native host plants to lay their eggs on. Did you know they also need mud puddles in order to be successful and abundant reproducers? Why? Keep reading and we’ll tell you.
If you’ve ever seen a group of butterflies gathered around a puddle you may have wondered what was so attractive in the mud. This is called ‘puddling’ and can also occur around dung, campfire ashes, carrion, and sometimes tree sap.
The butterflies are gathering sodium (Na) (salt) and other minerals from the saturated soil using their proboscis. Their proboscis has highly sensitive receptors to detect which puddles have greater concentrations of the salt they needopen_in_new.
Some butterflies, like these pictured above, gather around puddles in a kaleidoscope of mixed colors and speciesopen_in_new. Others, like the Spicebush swallowtail below, tend to gather only with the same species. Either way, research has shown that butterflies are more likely to gather where others already are, possibly as a foraging efficiency or a defense against predation. A decoy, even a wing from an expired butterfly, at a homemade mud puddle is likely to help get the party started.
Curiously, male butterflies dominate these gatherings around the watering hole; and, there have only been a few documented cases of females engaging in this puddling behavioropen_in_new. Research suggests that the minerals gained during puddling by the male butterfly are transferred to the female via spermatophore during copulation in what is known as a “nuptial gift”. This is actually common among many mating insects. Nutrient foraging effort differs among species, sex, and age classes; but, it is most often performed by younger males (just before breeding), leading to the spermatophore theoryopen_in_new. Females observed puddling were older and more worn out, possibly making up for long term deficiencies.
Moisture from mud puddles can contain the salt and minerals needed to sustain the female during egg production and ovipositing, which uses-up most of the the sodium they emerged with from the cocoon (up to 75% of their stores)open_in_new. Over the course of their adult life, however, female butterflies of researched species showed no net loss in their sodium content, even after repeated reproduction. This may indicate that they were being replenished by the males who do show a net loss of sodium over their lifetime despite emerging with higher sodium levels and engaging in puddling behavior.
Butterflies and moths are not the only wildlife that will appreciate easy access to a good mud source. Many birds, like American Robins and these Cliff Swallows, will use mud to build nests during their breeding season. Several types of bees will build hives or fill breeding tubes with mud and, of course, amphibians, like toads and salamanders, are known to play in the mud too.
Mud is needed by wildlife several times throughout the year when normal weather conditions would naturally create it. Urbanization and other forms of habitat loss, however, may make it difficult for wildlife to find a good source, leading to puddling or collecting mud in dangerous places like driveways or roadsides, near pesticide runoff, or unprotected from predators. Providing mud as habitat can attract these beautiful creatures to a site and reduce the risk they may face looking for mud in all the wrong places.
To provide mud for wildlife at your site you could simply make some, mixing soil and water and leave it out in a shallow tray or bowl. You can create a sodium solution with sea salt and water to add to the mud for a more compelling treat. For a larger installation, raised wooden boxes full of dirt or sand can be rewetted throughout the seasons as necessary, saturating the material but not leaving standing water. Be sure to use soil with a high mineral content and little organic material. Also, leaving some bare earth spots in your landscaping can create mud as weather or watering allows and will also provide this type of habitat throughout the year.
Add it to your habitat map.
Add a mud puddle habitat feature to your map and let us know you are providing unique and valuable resources for the wildlife in your neck of the woods. Start with the Ground Habitat tool and outline the area you want to dedicate to dirt. Double click on the habitat and give it a name like “Mudlick Saloon”. Then, fill in the Characteristics for the habitat; is it soil, sand, or gravel? In the comments section, indicate that this mud is for butterflies, bees, and birds. Be sure to provide any other information you want to contribute to let others know about your mud making!
Hint: Mud puddles are usually fairly small spaces so zoom into your map to be as accurate with the size as you can be.