534 Final Paper Daphne Payne How Does Clearcutting Affect Shrub Birds? England. In the 1800 s when farmers left New England for more prosperous soils

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1 534 Final Paper Daphne Payne How Does Clearcutting Affect Shrub Birds? Numbers of many shrub birds have declined as a result of habitat loss in New England. In the 1800 s when farmers left New England for more prosperous soils out West, they left behind rolling acres of cleared out agricultural fields. These fields grew into mature forests. Now, early successional stages of thicket are growing into mature forests and decreasing shrub habitat, specifically in Rhode Island, by a rate of % every year (Buffum et al., 2011). Many of the shrub birds that live in these declining habitats have strong fidelity to breeding sites; if their nesting sites disappear, they have no where else to go. In order to conserve these shrubland areas, studies are examining what requirements, exactly, create optimal shrub patch areas. Research is conflicting on which habitat factors are most sensitive to shrub birds. Some studies have found the size of the clearcut most affects bird abundance (Rodewald & Vitz, 2005). However, Askins et al. found that bird abundance was more influenced by the structure of the patch rather than the size. He found that, regardless of size, shrub birds prefer lower, thicker canopy cover. This indicates that shrub birds rely on specific vegetation types for habitat, and suggests that even small areas with optimal shrubs can be suitable for breeding and nesting. In New England this is important because scale is a lot smaller than the Mid West or West coast. A 300 ha clearcut is not feasible in a state like Rhode Island where the majority of the landscape is composed of a mosaic of smaller patches. However, smaller patches don t necessarily have to be an indication of poor quality habitat for

2 species if those patches contain the necessary food sources and breeding areas required by wildlife. One critical element to maintain optimal habitat in smaller clearcuts is to provide a straight edge. Shrub birds tend to avoid edges and a straight edge provides a higher ratio of interior than does a jagged edge (Rodewald & Vitz, 2005). This is especially important in smaller patches because even one meandering edge can decrease the interior of shrubland which is so important for nesting. Powerlines, for instance, because they have very straight edges are great habitats for shrubland birds (King, et al., 2009). An interesting debate I found in the literature was the question of when to call an edge an edge. Most studies agree that shrub birds tend to avoid clearcut edges and are found in the interior, however, there is disagreement on where that interior starts. Paton (1994) gives a very nice overview of the discrepancies of what is considered an edge. Studies have used buffers from the forest (which constitutes the edge of a clearcut) from 20 m to 1.5 km! I think this is an incredibly important variable which needs an operational definition. Is an edge scaled to the size of the patch? For instance, will the length of space that a forest transitions to a clearcut always be 1/10 the length of the patch? Is an edge always 50 m regardless of the size of the patch? Or is edge related to the change in vegetation and not related to size at all? If shrub birds tend to avoid edges, it is important for managers or property owners creating clearcuts to minimize their edge, and the first step to do this is to figure out just what, exactly, an edge is.

3 Creating a rotational clearcutting regime is the most effective way to maintain shrub bird diversity (Schlossberg & King, 2009). Many shrub birds have successional specific requirements for their nesting grounds. Carolina wrens, for instance, use a clearcut patch immediately post cut and will decline in abundance every year until about ten years post cut when it will leave the patch all together. A chestnut sided warbler, on the other hand, will begin to habitat an area post cut and will increase in abundance until about ten years post cut when the species will peak, then continue to decrease until they move away. A mosaic of patches will provide habitat for both these species. For example, a manager might clearcut a patch of a few acres, then in ten years or so when the early successional birds start to leave, create another clearcut adjacent to the first. One major problem with creating clearcut areas is the social perception that clearcuts are bad things. Before urban sprawl pushed development further into the wilderness, much of the forest clearing was created by beavers, wildfires, flooding and Native American agricultural practices (DeGraaf & Yamasaki, 2003). Now, however, most clearcutting activities are associated with logging or wildfires, which are destructive to residential communities. Many environmental organizations aim to halt companies which harvest timber, or spread awareness about the destructions of forest fires, and so these activities are seen as non environmental (Askins, 2001). Consequently, shrub habitats are decreasing. Furthermore, shrubland areas are not particularly attractive and the species who live there are shy and withdrawn, making these habitats seem unexciting and not very dynamic, another reason for the public s lack of enthusiasm for shrubland habitat.

4 In New England where much of the forest is privately owned by residents, it falls into the hands of property owners to properly manage the forest for habitat quality and species diversity. It is important to educate property owners on the necessities of having a variety of landscapes within their backyard to accommodate a variety of wildlife. Shrubland habitat, while not the best looking of those habitats, can be very easy to maintain and provide breeding and nesting grounds for many species who are declining throughout the region. Hopefully, if landowners respond to the call for more creation of these habitats, shrubland, and the species that depend on these areas, will begin to stabilize.

5 Annotated Bibliography Askins, R.A. (2001). Sustaining biological diversity in early successional communities: The challenge of managing unpopular habitats. Wildlife Society Bulletin, In this paper Askins provides a bunch of information on shrubs such as what they are, how to manage them, why they ve been declining and how much shrub land you really need. What I thought was the most interesting, however, was his reasoning for why shrub habitats are declining social perception. He points out how people think they are unattractive and undesirable. Furthermore, the species who dwell in these areas are withdrawn, not poster animals stirring up chivalrous emotions in the general public. This article appeals to the psychologist in me. Many times an issue becomes an issue because the rest of the world realizes (or thinks) it s an issue. Once people start demanding results, money gets distributed and time gets allocated to solving the problem. A major obstacle to shrub habitat is they aren t very pretty, and creating them requires actions that are apparently destructive (fires, logging). Possibly one aim to providing more habitat for shrub species is to get people excited about shrub land areas. Askins, R.A., B. Zuckerberg, & L. Novak. (2007). Do the size and landscape context of forest openings influence the abundance and breeding success of shrubland songbirds in southern New England? Forest Ecology and Management, These authors looked at whether small clearcuts provide suitable habitat for shrubland birds and promote bird richness. They looked at plots which ranged from.6 21 ha and which had been harvested in the past 3 11 years. They also recorded the vegetation at each study plot. Results show that shrub bird density was greatest at sites with a higher shrub density, lower tree cover, lower tree density and lower canopy height. This relationship was stronger than plot size, indicating shrub birds are more attracted to vegetation type when looking for habitat than patch size. I think it s interesting they found no relationship with patch size. This goes against most literature which supports a larger patch size. Larger patch sizes are argued as better habitat to provide an edge buffer, a patch of 1 ha doesn t really allow room for a buffer and interior. I think a question might become when is a patch still a patch and when is it just a lapse in forest. Or is this still a patch? Bosakowski, T. (1997). Breeding bird abundance and habitat relationships on a private industrial forest in the Western Washington Cascades. Northwest Science, This author is a consultant for a tree farm and aimed to determine the relationship between bird abundance and an industrial forest (the tree farm). He surveyed point counts for birds in the area for two years. He then overlayed the points onto GIS land use data (six categories: mature conifer, pole conifer, sapling conifer, alder hardwood, recent clearcut, and non forested land). He regressed the habitat onto each bird species and found that each of the six land uses are valuable to different and distinct groups of species.

6 Particularly on the East coast, industrial land can be stigmatized as poor animal habitat. This paper suggests that with proper management, industrial forests can also be suitable. Some companies probably don t try too hard to be beneficial to the environment because money outweighs extra time and effort for something like animals. If research can show that these companies can make money while simultaneously contributing to environmental protection, more companies might be more inclined to do both. However, Bosakowski was a consultant funded by the tree corporation he studied, which might not have influenced the results but should still be noted. Buffum, B., S.R. McWilliams, & P. V. August. (2011). A spatial analysis of forest management and its contribution to maintaining the extent of shrubland habitat in southern New England, United States. Forest Ecology and Management, This study calculated the spatial distribution of shrubland in Rhode Island using GIS land cover layers from various data sources and how that distribution has changed over the years to assess the effectiveness of management for these habitats. Results show that shrub habitat is decreasing in Rhode Island at an annual rate of % annually. Shrubland growing into mature forest is the major source of loss of shrubland habitat. I think this was a very rigorous study, lots of work went into it. They manually checked each forest/shrub polygon to determine how land use had changed from GIS is a great method of providing a visual example of how, and where, shrubland habitat is decreasing. Clearcutting is a sensitive subject to many people, and being able to show the comparison across time of exactly where, how much, and at what rate, certain land is being lost is a great tool. DeGraaf, R.M., & M. Yamasaki. (2003). Options for managing earlysuccessional forest and shrubland bird habitats in the northeastern United States. Forest Ecology and Management, 185: These authors give a history of disturbance in the northeast and suggestions for management. In the 1800 s disturbance occurred through a variety of factors (fire, native American practices, flooding, etc.). Now, however, due to urban sprawl, disturbance only occurs through wind and beavers. Because of this shrub habitat is declining and the species that rely on these habitats have no where to go. DeGraaf calls for a need to manage for shrub habitat. He gives a few management strategies to maximize optimal habitat, including size of patch, how often to rotate the clear cut and where prime locations for clearcutting are. I used this paper because I think it is a good example of an informative paper arguing a general cause. It was published by people working for the USDA so it could be targeted for land or park managers. It describes how valuable shrub land is and why we, in New England, are losing this area. Experiments examining bird success in clearcuts are great statistical evidence for the benefits of clearcut areas, but I think papers like this one are needed to point out the necessity of this habitat.

7 King, D.I., R.B. Chandler, J.M. Collins, W.R. Peterson, & T.E. Lautzenheiser. (2009). Effects of width, edge and habitat on the abundance and nesting success of scrub shrub birds in powerline corridors. Biological Conservation, These authors aimed to determine how much scrub shrub birds utilized powerline corridors as habitat. They monitored birds in bird count stations to evaluate nest success in powerline corridors of varying widths. Nest success was verified if there were fledglings in the surrounding area. They found low abundance of bird species in narrow corridors and the most abundance in corridors of medium width (between 50 60m). Nest survival was positively related to distance from edge. I think this is a perfect example of a management paper. It emphasizes the fact that something which is similar to a clearcut, and must be maintained for other purposes, can also be great habitat for birds. Since King, et al. found an optimal corridor width of 50 60m, perhaps the people who maintain powerlines could keep the areas within this range. Klaus, N.A., S.A. Rush, T.S. Keyes, J. Petrick, & R.J. Cooper. (2010). Short term effects of fire on breeding birds in Southern Appalachian upland forests. The Wilson Journal of Ornithology, These authors examine how fire severity and time after burn affects the diversity and abundance of bird populations. They looked at a variety of plots that had either not been burned (or burned more than 20 years ago), burned within the past 3 6 years or burned in the past 1 2 years. They also looked at burn severitylow, medium and high (levels categorized by vegetation mortality). They found that species richness was higher in burned (3 6 years after burn) than unburned areas. This implies that a fire regime can be an effective tool for avian conservation. Burning is relatively inexpensive so could be an efficient way to manage for clearcuts. I m not sure if the size of the area dictates whether burn is appropriate or not, something the authors could have discussed. Proximity to development is also a consideration, with the human wildlife interface pushing further and further into the wildlife side, burns become more important to manage. Paton, P.W.C. (1994). The effect of edge on avian nest success: How strong is the evidence? Conservation Biology, Paton s goal is to summarize conditions that affect predation and parasitism rates near clearcut edges. He studied this question in a meta analysis. Based on artificial nest studies, nest success is greater when the nest is further from the edge. However, what researchers were calling edge were buffers ranging from 20m to 1.5km. Also, not many studies specified why what they called an edge was actually an edge to the bird under investigation. I think this is one of the most important issues in dealing with clearcuts, and one that doesn t get discussed too frequently in the literature. Many articles declare that birds are edge specialists but then do not go on to give a definition of edge. In my opinion, an edge becomes an interior when the vegetation changes to shrub habitat. For some clearcuts there might be a slow transition from forest vegetation to shrub vegetation, and the buffer to the interior of the clearcut may be 500m, in

8 others this transition might be faster. I like that Paton pointed out that authors really have a mix bag of what they are calling edge, and there really is no one definition. I hope studies in the future will try to provide a more operational definition of edge. Rodewald, A.D., & Vitz, A.C. (2005). Edge and area sensitivity of shrubland birds. The Journal of Wildlife Management, These authors conducted a study in plot sizes 4 20 ha, 3 7 years post harvest. Using mist nets they found that more shrub birds were captured in the interior of clearcuts as compared to those captured along the edge. They determined that avian densities were more influenced by edge structure than size of plot. I think this is a good paper to address management techniques for providing habitat for shrub birds. Especially in Rhode Island, some forests might not be large enough to support big clearcut areas. For land owners who may want to create clearcuts to support shrub habitats but cannot afford to clearcut large patch sizes, creating clearcuts with straight edges great way to maximize productivity. Rudnicky, T.C., & Hunter, M.L.Jr. (1993). Avian nest predation in clearcuts, forests, and edges in a forest dominated landscape. The Journal of Wildlife Management, These authors looked at nest predation in both clearcuts and forest. They used clearcuts ha, 3 10 years post cut. They ran transects 300m into both clearcut and forest and positioned artificial nests along these transects. They found that nests in forests were more predated than nests along edges or in clearcuts. They also found the size of the clearcut did not affect predation rate. I think predation is a unique and great way to examine how habitats are affecting species. It would be extremely hard to do this type of study using real nests, but I would like to see if the trends are the same. Since shrub habitat is declining in New England, shrub birds are forced to go elsewhere to nest. This can seem like an abstract concept, and on first reflection might not seem to be a big deal, they can just go into the forest. But this study shows one concrete reason for why life is harder in the jungle there are more predators. Schlossberg, S., & D.I. King. (2009). Postlogging succession and habitat usage of shrubland birds. The Journal of Wildlife Management, These authors were interested in examining the change in bird densities in clearcut areas immediately after the cut and over a period of successional stages. They found that some avian species peaked the year after the clear cut and continuously decreased in the following years. Other avian species increased over the years, peaking around 10 years post logging, then decreased in abundance. Their analysis suggests that various birds use clearcut areas at various times. I think this is interesting because it indicates support for a rotating patchwork landscape. It would require work, but might maintain the highest level of bird diversity. It also supports a diverse habitat. Similar to how people plant flowers in their garden that bloom at different times throughout the year, successional stages support different birds throughout the years. This article shows an ideal

9 situation accommodating to shrub birds. I think the authors could have discussed how this type of rotation would affect other species as well, would a rotational clearcut help or harm other animals? This method, although painting a pretty picture of a healthy habitat, might not be feasible for private landowners managing their own property. Wallendorf, M.J., P.A. Porneluzi, W.K. Gram, R.L. Clawson, & J. Faaborg. (2007) Bird responses to clear cutting in Missouri Ozark forests. The Journal of Wildlife Management, These authors studied the effects of clearcuts in patches less than 13 ha on breeding birds. They measured birds in the clearcut, a buffer of 100m (which they considered the edge) and the interior forest. The site they used had a rotational clearcut harvest to meet a variety of goals, so at any given point there was a variety of growth areas both clearcut and no harvest. They measured birds using spotmapping and found that early successional bird densities were higher in the buffer zone. This is an interesting paper to consider because of their choice to use a 100m buffer. They opted to use 100m based on only one study, and didn t measure vegetation at all. The higher bird densities they found in the increase in buffer might very well have been considered early successional habitat. The use of when to call a buffer a buffer is important, you cannot just arbitrarily say this is where the interior of the clearcut is. There must be some definite way of defining a buffer. Either measure vegetation habitat, use transects, etc. While I think their article is useful, I think the interesting point they raise (albeit unintentionally) is how to choose your buffer.