The effects of past land use and exurban development on avian communities in Grafton county, NH

1. The effects of past land use and exurban development on avian communities in Grafton county, NH Will Yandik -- Brown University

9. Photo courtesy of Jonathan Deull

10. Primary question:Is avian species richness greater or lower in exurban developments relative to mature undisturbed forests? Exurban development is the fastest growing land use type in many regions and will likely dominant land use for central NH for the next several decades. Long-term avian monitoring at HBEF allow us to place exurban diversity data in context Grafton County exhibits a gradient of exurban development in relatively mature forests.

11. Does exurban development support higher or lower diversity?

12. Grafton County, NH - 4,500 km2- population 82,000 Boston 200 km

13. Cleared land, 1860 Hubbard BrookExperimentalForest BaldMtn. 50 km

18. Secondary question: Do former agricultural sites host higher or lower avian diversity than formerly logged sites?

19. Measuring avian diversity among land uses Agriculture Logging No Exurban Exurban

20. How do you measure land use?

23. How do you measure past land use? Stone walls, barbed wire, foundations mapped Soil profile documented Microtopography recorded Trees cored to estimate age

26. Past land use a significant driver for vegetation communities Percent Tree Cover Land Use Type

27. Species favoring conifers are more common in more intensive past land uses

28. Effects of Past Land Use Species Richness and Number of individual birds: Nominal differences among past land uses, most weakly significant or not significant Land Use Type Number quadratsNo. bird speciesNo. bird individuals Mean SD Mean SD Plowed 20 5.9 + 2.1 6.9 + 2.8 Pasture 119 5.4 + 1.8 6.5 + 2.3 Pasture woodlot 39 4.5 + 1.3 5.5 + 1.9 Woodlot 148 5.2 + 1.7 6.5 + 2.3 Mixed ag/woodlot 13 5.2 + 1.4 6.3 + 1.2 Sugarbush 7 5.1 + 1.6 6.3 + 1.7

29. Effects of exurban development(The importance of scale) • Quadrat • Transect • Paired transects • Regional analysis (BBS)

31. Quadrat level analysis No. of species of birds (p<0.000) Exurban (n=205) 6 + 2 species/transect Forested (n=275) 5 + 1 species/transect No. of individual birds (p<0.000) Exurban (n=205) 8 + 3 individuals/transect Forested (n=275) 6 + 2 individuals/transect

32. Transect level analysis No. of species of birds (p<0.000) Exurban (n=43) 17 + 3 species/transect Forested (n=54) 13 + 3 species/transect No. of individual birds (p<0.000) Exurban (n=43) 39 + 7 individuals/transect Forested (n=54) 31 + 6 individuals/transect

33. Paired transect level analysis No. of species of birds (p<0.000) Exurban (n=13) 18 + 3 species/transect Forested (n=13) 12 + 2 species/transect No. of individual birds (p<0.000) Exurban (n=13) 38 + 8 individuals/transect Forested (n=13) 28 + 6 individuals/transect

34. Preliminary Regression Results • No single tree species or suite of tree species predicts bird community richness • Edge a significant variable in all models • Shrub height (structure) and herb cover matter across landscapes • Even small structural changes matter • Density, vertical heterogeneity, age, arrangement

35. Why would disturbance increase biodiversity? • Landscape heterogeneity increases niches and packs more species in a given area • Exurban development (2008) apparently has not reached a negative threshold. • There remains an intact relatively undisturbed matrix of quality habitat.

37. Edge: Horizontal Structural Heterogeneity

38. Who benefits from disturbance? • Winners and Losers (values, not science) • Importance of guild level analysis (Interior, Edge, and Generalist species) “If there is any overall theme in the observed effects of human development on wildlife, it is that development tends to result in an increase in the representation of generalist, commensal species, and a decrease in representation of specialized and human-sensitive species.” Technical Report 3

39. Interior species

40. Edge species

41. Generalist species

42. Mean No. individual birds per guild in exurban and wooded quadrats ______________________________________________________ Exurban Wooded p-value Mean proportion + SD Mean proportion + SD _______________________________________________________________________ Interior 4.1 + 2 4.2 + 2 0.56 Generalist 2.5 + 1 1.8 + 1 0.000 Edge 1.2 + 1 0.1 + 0 0.000 ______________________________________________

43. Breakdown of interior species between exurban and wooded quadrats ExurbanWooded Taxonomic group No % No % _______________________________________________________________ Raptors 7 0.01 6 0.01 Gallinaceous 5 0.01 4 0.00 Woodpecker 38 0.04 64 0.06 Flycatcher 5 0.01 12 0.01 Vireo 52 0.06 64 0.06 Wood. Gleaners 81 0.09 119 0.10 Thrushes 56 0.06 48 0.04 Warblers 595 0.69 785 0.69 Tanagers 18 0.02 31 0.03 Grosbeaks 7 0.01 11 0.01 Total 864 1144

44. What do we do with this info? Are these data a license to build?

45. Structures, 1860

46. Structures, 1980

47. Road density, 1860

48. Road density, 1980 The landscape was more fragmented in the past than it is today. Is there a qualitative difference between the fragmentation in the past and today?

49. Effects of residential disturbance? Do summer homes have a smaller impact than year-round residences No. of interior species of birds (p<0.12) Occupied (n=69) 3.7 + 2 birds/quadrat Unoccupied (n=39) 4.1 + 2 birds/quadrat

50. Lag effects? By comparing date of house construction we can see if older houses (longer period of disturbance) host fewer species than new houses.