Restored and Natural Wetland Small Mammal Communities in West Virginia, USA

Round 1

Reviewer 1 Report

This study by Noe and others aims at comparing small mammal community characteristics between a natural and a restored wetland area. The paper is well written and clear. The results are not ground-shaking but solid and well interpreted. The authors avoid over-interpretation. The graphs and tables are adequate and clearly labelled – especially the map (Fig. 1) is appealing. The analysis appears sound and is based on a sound database. Despite rather slight differences in the ecological parameters of small mammal communities associated with a natural and restored wetland habitats, the authors managed to point towards species-specific differences. The paper shows the importance of small mammals as potential ecological indicators for ecosystem integrity. The paper further provides evidence for the importance to look at particular species to place light on rather difficile interrelations between biodiversity and land use. I think that this is a sound and solid paper that deserves being published in the journal Land after minor revision. I have a few comments and suggestions that I`ll outline below. I wish the authors good luck with this nice piece of work.

 

Line 58 ff.: When referring to the term “small mammals” for the first time, the authors might specify and say “terrestrial small mammals”, the term “small mammals” is a rather arbitrary and there are varying definitions, e.g. when using a threshold in body mass, bats (Chiroptera) would certainly also fall into this definition, while the authors surely not refer to bats here….

 

Line 60: After saying “small mammals” you specify and say “small rodents” but in the next sentence, you refer to a species of the group Eulipotyphla (a shrew) but not Rodentia – be careful and precise with your terms, rather stick to “(terrestrial) small mammals” throughout the manuscript.

 

Line 69: the authors mention various positive aspects of small mammal communities and their role as potential ecological indicators. All correct, all important but I am missing the thought that small mammals can also become pest species and can harm human livelihoods (e.g. crop damage or  reservoir for zoonoses). In fact, the concept of a bioindicator can be used in both direction: ecological parameters / community characteristics can help to inform about an increasing ecological integrity as a result of restoration measures. At the same time, changing community characteristics – e.g. the shift in species composition / the domination of a species can be an indicator for a emerging human wildlife conflict… Thus, I suggest the citation of studies that look at this two-directional usage of the concept of bioindicators in view of changing small mammal community characteristics following human-induced habitat changes, for example:

DOI: 10.3390/d12120488

 

Line 312ff: The authors write: “Another difference was that only six species were found in restored wetlands, as opposed to nine species found in natural wetlands, suggesting natural wetlands may have a greater ability to host a wider variety of small mammals.” I think you are referring to a wider variety of species but not necessarily animals.I wonder why the authors did not calculate a diversity index - a short explaination why diversity indices were not used would be helpful.

 

Chapter “4.1. Apparent Abundance, Occupancy, and Mass”: The interpretation is transparent and clear. I appreciate the fact that the authors discuss different species and their ecological characteristics and requirements individually. However, when looking at the link between vegetation patterns and small mammal characteristics, it appears that the authors look at the component of vegetation as a food resource but what about vegetation as a structure that provides shelter? I`d deeply appreciate a few thoughts about the link between ecological requirements and habits of individual species and the role of vegetation for shelter.

 

Chapter “4.2 Community composition”

Line 373-374: Authors write: “This result indicates that restored wetlands do not provide sufficient habitat for these species.” I`d be careful with such a statement! The fact that the authors did not catch certain species in a given environment does not necessarily mean that this species does not exist here and it can be problematic to judge about the sufficiency of the habitat based on a negative result. Suggest rewording and being more careful with the connection between habitat sufficiency and evidence of species occurrence.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

 

General comments

In ‘Restored and Natural Wetland Small Mammal Communities in West Virginia, USA’, Noe et al test the hypothesis that higher taxonomic richness in the plant community of restored, relative to natural, wetlands will result in higher abundance, occupancy probability and more diverse species composition of small mammal communities in restored wetlands. They test this hypothesis using an extensive trapping program over two-year period in 26 wetlands. They arguably find more support for a greater contribution from natural wetlands (the opposite conclusion), albeit still finding restored wetlands make a valuable habitat contribution.  

The paper is well written and clear, uses appropriate methods to test an important question and all conclusions are well supported by the evidence. I have little to add, some fine tuning perhaps, but suggest some additional mention could be made of the relative vegetation composition in natural vs restored wetlands (given the hypothesis is somewhat premised on an assumption of higher vegetation diversity in the latter).

I had some thoughts on alternative or complementary methods that could be used to analyse some of the data, which I include in the relevant sections providing specific comments. I view none of these as necessary but include them as possible suggestions for future analyses.

Best regards,

Dave Deane

 

Specific comments:

L98 (ish). Nice that you have given a breakdown of sampling effort for natural vs restored sites by year; I imagine you have similarly divided effort across ecoregions, a simple statement could be added to clarify this.

L149: I get that in most cases the wetlands are in clusters of both restored and natural and I am sympathetic that study designs must first be practical. Looking at Fig. 1, there are some closely paired sites (say within a few km) but also rather a lot (of both types) that are spread far and wide. It might not matter, but if you have not already, I would recommend testing for any spatial autocorrelation in model residuals, to see whether distance decay in compositional similarity could be influencing the results (e.g., a Mantel test of the distance between resids and the distance between sites). If there was spatial autocorrelation, it could be worth incorporating the spatial structure of the design in the models.

L204: Word missing here? (‘unmarked’ doesn’t seem to relate to anything).

L210: Use of NMDS is fine, but you could also consider clustering the sites (e.g., base R, hclust(), Ward’s method is one I like to use as it tends to identify tight clusters of sites). Then, depending how the sites fell out, you could compare cluster membership both in terms of natural and restored (i.e. does mammal composition in these wetlands group together or is it mixed among clusters). You do this a bit for wetland type in the NDMS with convex polyhulls, but you could do the same for bioregion and sampling year. That said, if you are going to that much trouble, you might as well use a constrained ordination method like dbRDA (vegan has a function to run this, with vignettes around online), which would allow you to test for stat. sig. groupings in composition across those factors. You can also incorporate a geographical distance matrix to account for spatial proximity.

L211: Being a bit picky here, but I think you mean data types, rather than data?

L222: anosim?

L228: Seems a breakdown of the raw corrected captures and recaptures by wetland type might also be interesting here? (I realise you model this, so up to you).

L244: I would never be prescriptive about this, but strictly enforcing a Neyman-Pearson null hypothesis interpretation (i.e., binary conclusion) of type 1 error is a little frowned upon these days. I would simply say the evidence of a difference was marginal. At your sample size, I suspect this could still be a biologically important pattern (probably not a random event). At the risk of being pedantic, in terms of the wording, the null hypothesis is that the populations are the same and you are unable to provide evidence that they differ if the type 1 error rate is above some threshold. I think it would be more correct to say ‘no evidence that they differ’ rather than that they are statistically similar (test assumes they are the same).

L185: I don’t quite follow here – was one single model fit for the mass of every species, or were separate models fit for each species? It seems from Table 2 you’ve done the latter, which is fine, but would be good to clarify here.

L256: This is a bit hard to follow. I know it seems boring, but repeating the taxon to which each statement refers would be really helpful. I would consider shortening this paragraph with a couple of sentences summarising the overall lack of any evidence of a difference  (I note you do start with this already). You could then add a couple of catch-all sentences grouping results along the lines of ‘Numerically, mean body mass tended to be higher in restored wetlands (e.g., sp1, sp2, Table 2), however none of these differences were statistically different from zero’.  

L308: It might be nice to start with reference to your hypothesis here (which we can probably reject with reasonable confidence) and go through the lines of evidence (as you do) to support it. Just a suggestion.

L327: Yes! Nicely put, I completely agree. You could add something about the relatively small sample size to support this if you liked.

L335: Interesting.  I was wondering about the role of wetland age more broadly. If you were as well, you could plot your model residuals for the restored sites against wetland age to see if there are any patterns. This would also be a good place to revisit your hypothesis, and the role of vegetation diversity in small mammal habitat use. EG was there even any evidence that veg div was higher in resto wetlands?

L337: Is it really just time? That is, will all wetlands inevitably become dominated by woody veg? I get it takes a minimum of time for trees to grow, but this seems to imply all wetlands end up heavily wooded. That might be true, it’s just not something I would expect (necessarily).

L342: Interesting. It seems unlikely to be variation in weather patterns, given the consistent pattern? (you could test that of course, albeit in a post hoc exploratory sense). Could the deer mice be a superior competitor in natural wetlands? Was there any evidence of negative association in abundance between their numbers in resto v natural wetlands? Note I’m a wetland plant person, so be aware I could be talking complete nonsense.

L346: This sounds a bit like you are saying deer mice had a greater mean abundance because you caught more – do you mean at more sites?

L370: Yes, it would be interesting to see what it was about the sites that did not overlap (in terms of whether they were the more remote ones for example, or whether they were all from a given bioregion/sampling year).

L417: Be mindful of your global readers – this sounds like a bit of local legislative jargon? Fine to include it, but worth a sentence explaining the context for international readers.

 

 

Author Response

Please see the attachment.

Author Response File: Author Response.docx