Hi all,

Can anyone point me to any information on the utility of wildlife habitat structures such as you commonly see in wetland mitigation sites? My opinion is that are generally a waste of time and money, but I'd really like to see some data to either back me up or educate me on their utility.

Thanks.

Andy

Andrew,

I cannot point you to any sources but can only relate the one experience I have had concerning this area and it may not even be what you are talking about.

I worked on a mitigation project where the field mice were girdling the planted trees and really causing a problem. We took 2", 20' galvanized pipe sections and on top of them, a "T" fitting was added and a 2' section off of each side of the T. This made a nice 4' perch section for birds of prey to sit and watch for the mice. A regular hand auger was used to auger down to 4' - 5' deep and the pole was stood up and soil compacted back around. As I have seen hawks perched up on these poles, they must be using them for something and the newest project has not had the mice concerns yet that the old one did so hopefully they are working! The poles also make location in the field a little easier since it gives you a good high object to focus on in the distance.

Other than that, windrows of stump piles make pretty good habitat but I bet you won't get much credit for it

From the standpoint of herps, designing the mitigaiton area to accommodate seasonal fish-free pools suitable for amphibian breeding is an excellent wildlife habtat structutre that will get a great deal of use through time.

However, I guess the wetland as a habitat structure is not where your particular interest was focused. On the artificial structure side, the supporting literature for the effectiveness (both absolute or from a cost-effective standpoint) is lacking.

While I cannot cite any particular references for this, clearly bat boxes stand out as a very effective wildlife habitat structure. These boxes are used by a wide variety of bats, including the occasional protected species. Bats then in turn put some sort of dent into the aquatic insect population by feeding on emerging adults - although the efficacy in ridding us of mosquitoes is very poor (probably due to foraging optimization: beetle = much energy, mosquito = very little energy, but that is off topic). As we are not plagued with exotic bat species, these structures also do not tend to attract or be used by exotic pests. The same can not be said of bird boxes and nesting islands, which can attract exotic species. From an efficacy standpoint, use by exotics must be construed as a negative factor.

The previous responder's use of raaptor perches does seem to be a good addition (assuming there are no nearby airports that would have BASH issues) as it appeared to add some visible and charismatic critters at the expense of providing a means of contributing to control of some less desirable wildife (field mice are wildlife too!).

Hopefully you can get some respondents that have more direct knowledge of some useful literature.

The main problem I have seen with final grading of mitigation areas is we want an undulating surface for a variety of slightly higher and lower spots on the site like Rich talks about. When you ask an equipment operator to do this, it goes against the very grain of what these guys have ever done! They think flat, we want natural undulations. It is almost easier to let them get it flat and then tell them to go "tear it up" a little bit. They still think YOU are crazy for asking for such a thing

What is "habitat" in nature for several species? Downed trees, stump holes, overturned trees where roots are ripped out and you have a small pool with adjacent stump and downed tree. So again, root balls, root wads, windrows and piled debris all have their place but must have conformation from agencies since they will think that you are just trying to leave debris debris on the site to keep from having to remove it.

And Rich, I agree that the field mice are an important component in nature, but when they threaten one your success criteria (tree count) then they may be a problem. This would have to be evaluated on a site by site basis to see if they are actually a problem.

I do like the idea of the bat boxes. Are they often used in a newly planted, wide open site where the boxes are completely exposed? ... good idea to put on the bottom of the perches?? I would think maybe not but wondering what 'yall think.

GOOD POST! I hope others will have input as well.

I know of no reference that talks about "wildlife structures". However for any classic structural type there is plenty of reason to include them in a mitigation project. Is there someting about the goals of the project that will support using them? For example "haul out logs" are important turtle, snake and alligator basking structures, and they are important loafing structures for some waterfowl and wading birds. But, in a wetland that is not going to attract some animals that use them, there is no point in including them.

So with structures such as brush piles (properly constructed), loafing structures, nesting structures, etc. that have a specific purpose and known value lets give it a go.

Now, what about some of those more nebulous structures? When, where, and why do we use "root wads." If they are good for something lets use them, but if there purpose is to add organics, increase diversity, and provide habitat for who knows what, then it is the blind leading the blind.

Lets remember that wetlands are constructed and restored to provide specific functions and that structures that we place in the wetlands should support those functions. Otherwise it is the blind golfer standing on the tee with hundreds of golf balls at his feet and he is swinging like crazy saying "Who knows when I might hit one in the direction of the green, wherever that is."

Andy:

There may be some information from the Federal Highway Administration on mitigation sites and/or projects they've constructed through the state DOTs. I know that on Alligator Alley (I-75) in Florida, there are multiple wildlife crossings that were incorporated into the design for various species, but I think concentrating on the Florida Panther. Of course, Alligator Alley crosses a large portion of the Everglades and I think a portion of the Big Cypress Swamp.

You may also want to contact the Florida Fish and Wildlife Conservation Commission on any potential projects they have coordinated through landowners or agencies for wildlife crossings in Florida. Jim Beaver in the Punta Gorda office of the FFWCC (if he's still with them - I've been out of Florida for several years) is a good contact from a historical standpoint.

Out here in Arizona, there is some general guidance on wildlife structures from the Arizona Game and Fish Department, but they are non-specific to wetlands. Arizona DOT has performed or is performing a study on State Route 260 for elk.

I hope this helps.

Dave

Andrew,

If you are required to construct habitat such as Gary has described, then it is a waste of time and money as you have stated in your original post. You can't even pile up brush to suit folks these days. You take something really simple and just make it overly complicated.

Root wads may be nebulous to some, but in other areas of the country they are recommended by state agencies, primarily for erosion control in stream restoration. I have seen just about every type of wildlife in eastern NC seeking shelter in downed trees and overturned stumps (I would probably call that a natural "root wad"). Been scared to death many times with racoons, rabbits, snakes, birds, ect. that come blasting out of some brush pile or stump as I am crawling over it, so these natural areas are used by all forms of wildlife. Never seen a black bear that waited to have his bed "properly contructed" by humans before occupying it, he will make his bed cozy just fine without us.

... and now increasing species diversity is a bad thing?

Come on Gary, tell me you were kidding about the constructed brush pile

Yep, properly constructed brush piles, no kidding. There is abundant literature on brush piles and they can be built to enhance selected species or to provide "whatever." For my part, wetland construction and restoration to provide habitat for "whatever" is a major source of the criticism leveled at the technology of habitat restoration.

Going back to the original question re data on wildlife structures; I am reading a quite interesting book written by the Bocks of Col State University that provides a summary of their research in Arizona over the last 30 years comparing ecological differences in grazed vs ungrazed habitats over time. One of their experiments was designed to test some theories regarding the relative role of nesting habitat availability vs competition on riparian breeding bird success. What they found was that artificial nesting structures in arid riparian systems did increase the breeding success of some native bird species, but that it was at the expense of the breeding success of other native bird species. Not quite proving one theory or the other, but supporting what Gary just noted-that providing habitat for “whatever”can be controversial (at least in some circles).

The role of structural components in aquatic systems (root wads, log jams etc.) has just started to be evaluated scientifically. Some of the early data I saw showed no statistical difference in target fish populations between pre and post-structure treatments. This may be due in a large part to the monitoring design and the system variability, as well as the short term nature of the monitoring. Stan Gregory’s team at Oregon State has been working on some more rigorous sampling over a period of years which should help to provide some scientific data on the short and long term responses to aquatic habitat structures in the PNW.

Andy,

Can you be more specific? Are talking of structure within the wetland environment itself such as microtopography, LWD, brush piles, or are you referring more to peripheral structures such as bird boxes, bat boxes, etc.

Dave

I have seen log structures placed in ponds as a mitigative measure for the benefit of turtles. In those cases, the target was red bellied turtles, (a threatened species in Pennsylvania)and in my opinion the structures were successful. However, the structures were also utilized by other turtles, some of which were non-native to the location. You can argue the pros and cons of this issue forever and not reach any agreement. Some will say it was a failure because a non target species was benefited. some will say it was a success because some individuals from the target species were benefited. If you are just doing whatever to benfit whatever, then whatever happens is an invitation for failure. However, if you have specific material resources, a specific plan that can utilize those resources, and a specific site or species that could benefit from that work, I think it is a wise and prudent thing to do as long as you properly plan it and implement it. The problem I see too often is that the ultimate regulatory review and approval can become so convoluted, particularly with process, that what starts as a small and beneficial idea becomes the crux between success and failure at some distant place and time.

In the past 30 years I have seen MANY artificial nesting structures utilized by osprey. The installation of these nesting structures in a coastal wetland, whether it is man-made or natural, clearly benefits the species and man. The osprey has an alternative to the navigation marker, light tower, or electric tower.

This is a great discussion - and the stuff that wetland scientists should be talking about!

Hard structure aka "wood duck boxes" often achieve as much non-target use (wrens, sparrows, snakes) as they do target use, particularly when the structures are not maintained (say, after a mitigation monitoring period ends). There is endless data on this topic.

As for herp structures, etc; a recent thesis at the U of Delaware (Amy Alsfeld) should hopefully be turned into white papers soon - it looked at numerous voluntary (non-mitigation) wetland projects constructed by various groups (USFWS, DE Fish and Wildlife, etc) to evaluate the effectiveness of microtopo, fine woody debris, coarse woodies, and organic soil amendments. The findings were interesting (complicated) and I think professionals in the mid-Atlantic should see it for themselves - so I don't misquote it!

I fully support adding structure to wetlands where it's appropriate. The biggest problem I have experienced over the years has been exactly what Chip, Ed, and others have brought up - that "over-infusion" of structural components that reflects the regulatory world's "design by committee" mantra. I.e. you have to have less than 10% deep pools for USACE approval, but at least 20% deep pools for NMFS approval. The state DEP wants fallen snags for runways for endangered mice, while the state DNR believes that wooden runways excacerbate predation, and requires that all debris be removed from site. What a mess!

One of the great things about non-compulsory habitat work is that you can have a lead agency (and funder), behind whom other folks generally concur until they are bent way outside their focus. This ensures that a project fully reflects the goals of the lead agency, while hopefully also incorporating some input from other agencies.

In the case of mitigation, it would be nice if the Corps or USFWS could fulfill this "lead agency" role (I know that the Corps has it...on paper), to make sure FUNCTIONS, not just acreages and non-scientific aesthetics, are achieved!