Data Exploration
Predictor Variables
For this study, the predictor variables consist of the sex of the bear (Female, Male, or No Bear) and the dominant vegetation class (13 types documented). Half of the data is from the paired "non-bear activity sites", meaning that sex of the bear is a null value; however, vegetation data is available for use and non-use sites.
As shown in Figure 5, visits to bear use sites were approximately evenly divided between male and female bears, with a slight bias towards males.
There was also an imbalance in the number of observations of each of the thirteen dominant vegetation types (Figure 6), with conifer obviously being the dominant vegetation type for almost half of the sites surveyed. In some future analyses, vegetation types that have three or fewer observations will be removed.
As shown in Figure 5, visits to bear use sites were approximately evenly divided between male and female bears, with a slight bias towards males.
There was also an imbalance in the number of observations of each of the thirteen dominant vegetation types (Figure 6), with conifer obviously being the dominant vegetation type for almost half of the sites surveyed. In some future analyses, vegetation types that have three or fewer observations will be removed.
Response Variables
The response variables for the study are the values of birds detected at each of the sites. As seen in Figure 7, the total counts of each of the 36 species detected are variable, with White-throated Sparrow (WTSP), Lincoln's Sparrow (LISP), Varied Thrush (VATH), and American Robin (AMRO) being the most observed. Birds with fewer than 10 observations will be removed from some future analyses (will be noted). Any birds which were unable to be identified to species were removed from the analyses. All analyses which refer to bird species or species values, refer to the counts of each species observed at each site (not simply presence / absence).
Ordinations
To attempt to identify whether there were any groupings of bird species based on whether the site was defined by male, female, or no bear activity, an NMDS was used.
There are clearly no defined groups, indicating that songbird species are perhaps not strongly driven by the sex of the bear, or given the "no bear" grouping, the presence of bears at all.
The LISP (Lincoln's Sparrow) and WTSP (White-throated Sparrow) vectors are much larger than the other species, indicating their large impact on the ordination. This is of course logical, given that they are the two most frequently observed species.
There are clearly no defined groups, indicating that songbird species are perhaps not strongly driven by the sex of the bear, or given the "no bear" grouping, the presence of bears at all.
The LISP (Lincoln's Sparrow) and WTSP (White-throated Sparrow) vectors are much larger than the other species, indicating their large impact on the ordination. This is of course logical, given that they are the two most frequently observed species.
Following the NMDS of birds based on sex of the bear (Figure 8) which didn't show any clear groupings, we ran an NMDS of the same bird data using dominant vegetation type as our grouping mechanism (Figure 9). We used only vegetation types that had more than three observations to attempt to improve clarity. Similar to our previous NMDS, there were no clear groupings of songbirds by dominant site vegetation.
Image References
Barrette, S.P. (Photographer). (2012). Setophaga coronate MP [digital image]. Retrieved from: https://commons.wikimedia.org/wiki/File:Setophaga_coronata_MP.jpg
Barrette, S.P. (Photographer). (2011). Zonotrichia albicollis CT1 [digital image]. Retrieved from: https://commons.wikimedia.org/wiki/File:Zonotrichia_albicollis_CT1.jpg
C, Andrew. (Photographer). (2015). Clay-colored Sparrow (Spizella pallida) [digital image]. Retrieved from: https://commons.wikimedia.org/wiki/File:Clay-colored_Sparrow_(Spizella_pallida)_(19482161375).jpg
Kristof vt (Photographer). (2005). Turdus migratorius-002 [digital image]. Retrieved from: https://commons.wikimedia.org/wiki/File:Turdus-migratorius-002.jpg
Majoros, W.H. (Photographer). (2011). Wilsons Warbler-2a [digital image]. Retrieved from: https://commons.wikimedia.org/wiki/File:Wilsons-warbler-2a.jpg
Reago, A. and McClarren, C. (Photographer). (2016). Chipping Sparrow [digital image]. Retrieved from:
https://commons.wikimedia.org/wiki/File:Chipping_Sparrow_(25771728463).jpg
Reago, A. and McClarren, C. (Photographer). (2017). Hermit Thrush [digital image]. Retrieved from: https://commons.wikimedia.org/wiki/File:Hermit_Thrush_(33428187844).jpg
Reago, A. and McClarren, C. (Photographer). (2017). Lincoln's Sparrow [digital image]. Retrieved from: https://commons.wikimedia.org/wiki/File:Lincoln%27s_Sparrow_(33918959600).jpg
Reago, A. and McClarren, C. (Photographer). (2016). Orange-crowned Warbler [digital image]. Retrieved from: https://commons.wikimedia.org/wiki/File:Orange-crowned_Warbler_(30261373000).jpg
Reago, A. and McClarren, C. (Photographer). (2017). Ruby-crowned Kinglet [digital image]. Retrieved from: https://commons.wikimedia.org/wiki/File:Ruby-crowned_Kinglet_(34090209002).jpg
US Fish and Wildlife (Photographer). (2005). Ixoreus naevius FWS [digital image]. Retrieved from: https://commons.wikimedia.org/wiki/File:Ixoreus_naevius_FWS.jpg
Barrette, S.P. (Photographer). (2012). Setophaga coronate MP [digital image]. Retrieved from: https://commons.wikimedia.org/wiki/File:Setophaga_coronata_MP.jpg
Barrette, S.P. (Photographer). (2011). Zonotrichia albicollis CT1 [digital image]. Retrieved from: https://commons.wikimedia.org/wiki/File:Zonotrichia_albicollis_CT1.jpg
C, Andrew. (Photographer). (2015). Clay-colored Sparrow (Spizella pallida) [digital image]. Retrieved from: https://commons.wikimedia.org/wiki/File:Clay-colored_Sparrow_(Spizella_pallida)_(19482161375).jpg
Kristof vt (Photographer). (2005). Turdus migratorius-002 [digital image]. Retrieved from: https://commons.wikimedia.org/wiki/File:Turdus-migratorius-002.jpg
Majoros, W.H. (Photographer). (2011). Wilsons Warbler-2a [digital image]. Retrieved from: https://commons.wikimedia.org/wiki/File:Wilsons-warbler-2a.jpg
Reago, A. and McClarren, C. (Photographer). (2016). Chipping Sparrow [digital image]. Retrieved from:
https://commons.wikimedia.org/wiki/File:Chipping_Sparrow_(25771728463).jpg
Reago, A. and McClarren, C. (Photographer). (2017). Hermit Thrush [digital image]. Retrieved from: https://commons.wikimedia.org/wiki/File:Hermit_Thrush_(33428187844).jpg
Reago, A. and McClarren, C. (Photographer). (2017). Lincoln's Sparrow [digital image]. Retrieved from: https://commons.wikimedia.org/wiki/File:Lincoln%27s_Sparrow_(33918959600).jpg
Reago, A. and McClarren, C. (Photographer). (2016). Orange-crowned Warbler [digital image]. Retrieved from: https://commons.wikimedia.org/wiki/File:Orange-crowned_Warbler_(30261373000).jpg
Reago, A. and McClarren, C. (Photographer). (2017). Ruby-crowned Kinglet [digital image]. Retrieved from: https://commons.wikimedia.org/wiki/File:Ruby-crowned_Kinglet_(34090209002).jpg
US Fish and Wildlife (Photographer). (2005). Ixoreus naevius FWS [digital image]. Retrieved from: https://commons.wikimedia.org/wiki/File:Ixoreus_naevius_FWS.jpg