Landbird HSI Model Draft • Tirpak and Jones-Farrand1
Painted Bunting (Passerina ciris)
Status:
The painted bunting occurs as two allopatric populations that may represent separate species (Thompson 1991). The western population occurs in the southern Great Plains and the western edges of the CH and WGCP, while the eastern population occurs along the Coastal Plain from North Carolina to Florida (Figure 95). Populations have been relatively stable across the entire WGCP (Appendix 1). However, within this region, populations have declined in Arkansas (-5.8%, but nonsignificant), Louisiana (-3.5%), and Texas (-2.4%) while increasing in Oklahoma (1.3%). The painted bunting is not considered a Bird of Conservation Concern (Appendix 2), but with a total priority breeding score of 16 and 17 is classified as a Tier 1 priority bird in both the CH and WGCP, respectively (Appendix 3).
Figure 95. Relative abundance of painted buntings, derived from Breeding Bird Survey data, 1994 – 2003.
Natural History:
The painted bunting is a colorful neotropical migrant that has 2 distinct breeding populations in the U.S.: one along the southeast Atlantic coast from Florida to North Carolina, and one ranging from northern Mexico into Kansas and Mississippi (Lowther et al. 1999). The habitat requirements of the western population are not well understood. It is generally found in areas of scattered wooded vegetation. Kopachena and Crist (2000a) characterized painted bunting habitat in northeast Texas as “wooded areas in otherwise open habitat” as opposed to indigo buntings which occurred in “open areas in otherwise wooded habitat.” Painted buntings in their study also occurred in smaller, more heterogeneous groups of trees than indigos. Microhabitats differed little between the species (Kopachena and Crist 2000b). Conner et al. (2004) found painted buntings in narrow riparian zones in eastern Texas, where they decreased quickly at widths >20 m and were absent at widths >70 m.
Nests are constructed in low, woody vegetation (Lowther et al. 1999). Territory size varies with population density. In Missouri, territories ranged 0.64-6.66 ha and included 80% pasture and 20% woodland. This species is a common host of both brown-headed and bronzed cowbirds.
Model Description:
The relative density model for the painted bunting contains five parameters: landform, landcover, age class, distance to edge, and interspersion of forest and open habitats.
The first suitability function combined landform, landcover, and age class into a single matrix (SI1) that defined unique combinations of these classes. We then directly assigned relative density values to these combinations based on habitat suitability data from Hamel (1993; Table 113).
Painted buntings are an early-successional species associated with edges. We used data on territory density from Lanyon and Thompson (1986;Table 114) to define a linear function linking relative density to distance from an edge (SI2; Figure 96).
Interspersion of forest and open habitats (SI3) is perhaps the most important component of painted bunting habitat. We maximized relative density of painted buntings in landscapes containing 20% forest and 80% open habitats (average configurations for buntings in Missouri; Norris and Elder 1992 cited in Lowther et al. 1999) and reduced relative density values as proportions moved away from this optimal configuration (Table 115).
Because the painted bunting is an early successional species, it is typically associated with habitats containing high stem densities (SI4). We assumed mean stem density values observed by Kopachena and Crist (2000) were associated with maximal bunting density and assumed bunting would be absent in habitats with either no stems or twice the mean number of stems (Table 115b). We fit a smoothed quadratic function to these data points (Figure 96b) to assess the effect of stem density on relative density of buntings.
We calculated relative density as the geometric mean of the four component functions.
Relative density = (SI1 * SI2 * SI3 * SI4)0.250
Relative productivity was a function of two factors: the proportion of forest in the landscape (10 km radius buffer; SI5a) and presence of edge(SI5b). We defined the functional relationship between landscape composition, edge, and relative productivity based on data from Robinson et al. (1995) and Donovan et al. (1997) and the susceptibility of each species to cowbird parasitism (Figure 97, Table 116).
SI1: Landform, landcover type, and age class
Table 113. Relationship between landform, landcover type, age class, and relative density of painted buntings. Values in parentheses apply to West Gulf Coastal Plain..
Successional Age Class
Landform / Landcover type / Grass-Forb / Shrub-Seedling / Sapling / Pole / Saw
Floodplain/Valley / Low-density Residential / 0.000 / 0.000 / 0.000 / 0.000 / 0.000
Transitional/Shrubland / 0.000 / 0.167 / 0.167 / 0.083 / 0.000
Deciduous / 0.000 / 0.167 / 0.167 / 0.083 / 0.000
Evergreen / 0.000 / 0.000 / 0.000 / 0.000 / 0.000
Mixed / 0.000 / 0.000 / 0.000 / 0.000 / 0.000
Orchard/vineyard / 0.000 / 0.167 / 0.167 / 0.083 / 0.000
Woody Wetlands / 0.000 / 0.333 / 0.333 / 0.167 / 0.000
Terrace/Mesic / Low-density Residential / 0.000 / 0.000 / 0.000 / 0.000 / 0.000
Transitional/Shrubland / 0.000 / 0.000 / 0.000 / 0.000 / 0.000
Deciduous / 0.000 / 0.000 / 0.000 / 0.000 / 0.000
Evergreen / 0.000 / 0.000 / 0.000 / 0.000 / 0.000
Mixed / 0.000 / 0.000 / 0.000 / 0.000 / 0.000
Orchard/vineyard / 0.000 / 0.000 / 0.000 / 0.000 / 0.000
Woody Wetlands / 0.000 / 0.333 / 0.333 / 0.167 / 0.000
Xeric/ridge / Low-density Residential / 0.000 / 0.000 / 0.000 / 0.000 / 0.000
Transitional/Shrubland / 0.000 / 0.000 / 0.000 / 0.000 / 0.000
Deciduous / 0.000 / 0.000 / 0.000 / 0.000 / 0.000
Evergreen / 0.000 / 0.000 / 0.000 / 0.000 / 0.000
Mixed / 0.000 / 0.000 / 0.000 / 0.000 / 0.000
Orchard/vineyard / 0.000 / 0.000 / 0.000 / 0.000 / 0.000
Woody Wetlands / 0.000 / 0.333 / 0.333 / 0.167 / 0.000
All landforms / Herbaceousa / 1.000 / 0.000 / 0.000 / 0.000 / 0.000
Non-habitatb / 0.000 / 0.000 / 0.000 / 0.000 / 0.000
a Includes natural grasslands, pasture/hay, fallow, urban/recreational grasses, emergent herbaceous wetlands.
b Includes open water, high intensity residential, commercial/industrial/transportation, bare rock/sand/clay, quarries/strip mines/gravel pits, row crops, and small grains.
SI2: Distance to edge
Table 114. Influence of distance to edge (m) on relative density of painted buntings.Distance to edge (m) / Relative density
0-90 a / 1.000
90-150 a / 0.700
150-210 a / 0.300
>210 a / 0.000
a Lanyon and Thompson (1986)
Figure 96. Relationship between distance to edge(m) and relative density of painted buntings.
Equation: Relative density = 1.267 – (0.005 * distance to edge)
SI3: Interspersion
Table 115. Values of SI3 (relative density of painted buntings) based on proportion of cells providing roosting and nesting habitat within a 5-ha moving window.Proportion in foresta / Proportion in openb
0.0 / 0.1 / 0.2 / 0.3 / 0.4 / 0.5 / 0.6 / 0.7 / 0.8 / 0.9 / 1.0
0.0 / 0.0 / 0.0 / 0.0 / 0.0 / 0.0 / 0.0 / 0.0 / 0.0 / 0.0 / 0.0 / 0.0
0.1 / 0.0 / 0.0 / 0.0 / 0.0 / 0.25 / 0.5 / 0.8 / 0.9 / 0.9 / 0.9
0.2 / 0.0 / 0.0 / 0.0 / 0.0 / 0.25 / 0.5 / 0.8 / 0.9 / 1.0 c
0.3 / 0.0 / 0.0 / 0.0 / 0.0 / 0.25 / 0.5 / 0.8 / 0.9
0.4 / 0.0 / 0.0 / 0.0 / 0.0 / 0.25 / 0.5 / 0.8
0.5 / 0.0 / 0.0 / 0.0 / 0.0 / 0.25 / 0.5
0.6 / 0.0 / 0.0 / 0.0 / 0.0 / 0.25
0.7 / 0.0 / 0.0 / 0.0 / 0.0
0.8 / 0.0 / 0.0 / 0.0
0.9 / 0.0 / 0.0
1.0 / 0.0
aForest is upland forested, transitional, and woody wetlands
bOpen area is herbaceous natural or cultivated or emergent herbaceous wetlands
c Norris and Elder 1992; all other values assumed
SI4: Stem density
Table 115b. Influence of stem density (stems/ha) on relative density of painted buntings.Stem density (stems/ha) / Relative density
0 a / 0
6400 b / 1
12800 a / 0
aAssumed
b Kopachena and Crist (2000)
Figure 96b. Relationship between stem density (stems/ha) and relative density of painted buntings.
Equation: Relative density = 0.0003 * (stem density) – 0.00000002 * (stem density)2
SI5: Generalized productivity function
SI5a: Generalized productivity function (Forest composition)
Figure 97. Relationship between landscape composition (% forest in 10 km radius buffer) and relative productivity of painted buntings.
Equation: Relative productivity = (0.0076 * (% forest)) + 0.2434
SI5b: Generalized productivity function (Edge)
Table 116. Influence of edge on relative productivity values derived from landscape composition (% forest) for painted buntings.Forest composition / Edge a / Core
0-20% / X b / X
20-80% / X * 0.8 / X * 1.2 c
80-100% / X / X
a “Edge” defined as any forest pixels with a nonforest pixel within a 3 x 3 window. Forest-nonforest classification same as used in SI4a.
b X = value derived from SI4a
c Maximum value = 1