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Valmont Park Breeding Bird Study~^ ~... Valmont Park Breeding Bird Study ~.+ Stephen R Jones, Environmental Consultant 3543 Smuggler Way, Boulder CO 80305 13 September, 2001 ~ ~ ,~- t.. .-, ~r Acknowledgments 1 Introduction and Methods 2 Results and Discussion 2 Management 8 Future Research 8 Literature Cited 8 Appendix: Plot Summazies 9 Table of Contents ,.. ~... ~ ~ Acknowledgments Joy Master and Ann Wichmann contributed substarnially to tlris project by helping to locate breeding bird point-count stations and by assisting during all three breeding bird count sessions. ..... ~..i z ~ Inttoduction We surveyed breeding bird populations at the Valmont City Pazk site between 23 May and 11 July, 2001. The goals of the study aze: 1. To establish permanent breeding bird plots on the site so that bird populations can be monitored over time by volunteers and students. 2. To census breeding bird populations so that sensrtive nesting habitats can be protected during and after development of the pazk for active recreation. Breeding birds are strong indicators of environmental quality For example, the presence of "indicators species," birds that tend to nest within a single natural habitat type, may pomt to azeas dominated by nahual plant communities. On the other hand, a preponderance of urban-adapted species or habitat generalists (sometimes referred to as "weed species") may indicate high levels of ecosystem dis[urbance. Long-term monitoring of breeding bird populations can help park managers evaluate the effectiveness of natural ecosystem protection and restoration efforts. Methods We established seven point-count stations within the 132-acre pazk site, which is located north and south of Valmont Street between Foothills Highway and SSth Street (Figure 1). We visited ~ each count station three tunes (23 May, 15 June, 11 July), counting all birds seen or heard within a 100 m radius during an 8 minute penod. In addition, I conducted noctumal surveys for owls on 13 and 15 July During these owl surveys, I played tape recordings of barn owl and eastern screech-owl temtorial calls for 5 minutes each (30 seconds on, 30 seconds o~ from three locations within the pazk site (Figure 1). Resuks and Discussion We saw or heard a total of 33 species within the pazk site (Tables 1 and 2) We con8rmed nestmg for 8 species. An additional8 species probably nest on the site (territorial behavior observed in suitable nesting habitat), and 12 more spec~es may nest on the site (aduhs observed m suitable nesting habitat). Breeding bird abundance and species diversity was greatest in the northwestem portion of the pazk site (plots 1-3, north of Valmont Road), where riparian vegetation along two irrigation canals provides nesting habitat for species such as black-capped chickadee, song sparrow, and Bullock's oriole; and in the southeast corner of the park site, where a neazby wooded azea along Boulder Creek provides habitat for ducks and songbirds (Table 1). Breeding bird abundance and species diversity was lowest in the Goose Creek drainage, where there is little vegetative cover to shelter nests of breeding buds ~ ~ Figure 1. Valmont park site and breeding bird count station locations. 1-7: Point-count station locations A-C: Owl calling station locations ~ ~ \... 4 Table 1. Plot densities of breeding birds Mean number observed per count. ~ 1: Northeast 2: Northwest 3: North-central 4: Poplaz Grove 5: Prairie dog colony 6: Goose Creek 7: Knoll Species 1 2 3 4 5 6 7 All Black-crowned Night Heron 03 03 Mallard 03 0.7 0.7 0.3 2.0 Swainson's Hawk 0.3 03 0.6 American Kestrel 03 0 7 0 3 1.0 2.3 Killdeer 0.7 0 7 Rock Dove 2.3 2.0 13 1.0 6.7 Mouming Dove 13 I 0 1.3 3.7 Chimney Swift 0 3 0.3 0.7 13 Northem Flicker 0.7 03 0.3 1 3 Woodpecker species 0.3 03 Westem Wood-Pewee 0.7 0.3 0.3 13 Rough-winged Swallow 0.7 0 7 CGff Swallow 03 2 3 2.7 5 3 Swallow species 2.0 1.7 1.0 2.0 2 3 9.0 Blue Jay 0.3 1.0 0.3 0 7 2.3 Black-billed Magpie 1.0 1.7 1.7 1.0 1.0 13 2.7 103 Common Raven 0.3 0.3 ~ Black-capped Ctrickadee 0.7 0.3 1.0 House Wren 0.3 03 0.7 13 American Robin 1 3 0.7 03 0.7 03 33 European Stazluig 2.0 2.7 1.7 3.0 3 7 23 33 18.7 Yellow Wazbler 0 3 0 3 Song Sparrow 03 0.3 03 1.0 Red-winged Blackbud 0.7 0.7 Western Meadowlark 1.3 1.7 1.7 13 1 0 2.0 1 0 10.0 Brewer's Blackbird 3.3 0.7 2.3 3.0 2.0 0.7 23 14.3 Common C'srackle 1.0 0.1 1.7 1.0 0 3 4.7 Brown-headed Cowbird 03 1.0 0.7 2 0 Blackbud species 03 1.3 1.7 33 Bullock's Oriole 1.0 1.7 0.7 33 House Finch 0.7 03 8.7 0.7 2 3 12.7 American Goldfinch 03 03 0.7 House Sparrow 1.0 1.0 03 2.3 Songbird species 1.7 1.0 2.3 0 3 1 3 0 3 7.0 Mean Species 7.0 113 9 3 7.0 8.7 6.7 9 3 23.0 Mean Individuals 15.3 19 0 21.0 19.0 25.0 14.7 21.7 135.7 ALso observed within site: Great Blue Heron, Turkey Vukure, Great Horned Owl. ~ 5 ~ Table 2. Potential breeding species. Habitat codes: G- Grassland; R- Riparian woodland; U- Urban/other human shuctures; W- Wetland Breeding codes: Confirmed - occupied nest, nest with eggs or young, adults feeding young, recently fledged young. L~ely - territorial or other breeding behavior observed in suitable nesting habitat. Possible - aduks seen or heard in suitable nesting habitat. S~ecies Habitat Status Mallard W Possible Swainson's Hawk R Possible American Kestrel R Possible Killdeer G,U,W Possible Rock Dove U Likely Mourning Dove R Likely Great Horned Owl* R Possible Chimney Swift U,R Possible Northern Flicker R Confirmed Western Wood-Pewee R Possible C„~ Rough-winged Swallow R Possible Cliff Swallow U Confirmed Blue Jay R Likely Black-billed Magpie R Confumed Black-capped Chickadee R Lilcely House Wren R Likely American Robin R,U Confirmed European Starling R,U ConSrmed Yellow Wazbler R Possible Song Sparrow R Possible Red-winged Blackbird G,W Possible Brewer's Blackbird G,R Confirmed Common Grackle R,U Lilcely Brown-headed Cowbird R,G,U L~cely Bullock's Oriole R Confumed House Finch U,R Confirmed American Goldfinch R Possible House Sparrow U L~kely *Observed during owl surveys only. Great blue heron, black-crowned night heron, and turkey vulture were also observed during the breeding season, but the pazk srte does not contain suitable nesting habitat for these species. ~ Chazacteristics of Breeding Bird Population The pazk site's breeding avifauna is dominated by urban-adapted generalists, buds that thrive in urban or other disturbed environments. However, a few grassland and ripazian woodland specialists do nest on the site. The categorizations in Table 3 aze adapted from Ehrlich et al. (1988) and Kingery (1998). Table 3. Composition of Valmont Pazk Site Breeding Bvd Population UrbanJGeneralist ~arian Wood3and Grassland Mallazd American Kestrel Killdeer Rock Dove Mourning Dove Gteat Homed Owl Chimney Swift Northern Flicker Cliff Swallow Blue Jay Black-billed Magpie House Wren Amencan Robin European Stazling Red-winged Blackbird Brewer's Blackbird Common Gtackle Brown-headed Cowbird House Finch Western Wood-Pewee Rough-winged Swallow Black-capped Chickadee Yellow Wazbler Song Sparrow Bullock's Oriole American Goldfinch Swainson's Hawk Westem Meadowlark For three yeazs the Boulder County Audubon Society has censused bird populations along a 5 km reach of Coal Creek, on City Open Space south of Boulder. Tlvs section of the Coal Creek valley contains a mosaic of grasslands, shrublands, and nparian woodlands sirrular to that found on the Valmont Pazk site. Prior to urbanization of the Boulder area, these two areas pmbably supported similaz populations of breeding birds. A comparison of breeding bird species recently observed in the two azeas suggests that urban development in and azound the Valmont Pazk site has eliminated nesting habitat for a variety of species, especially those that typically nest in grasslands and riparian woodlands (see Table 4, following page). A total of 3 species were observed at Valmont Park but not at Coal Creek. A total of 25 species were seen at Coal Creek but not at Valtnont Pazk. Some of the more common species in this latter group, including downy woodpecker, ~rn swallow, and spotted towhee, pmbably nest occasionally at the Valmont Pazk site. Others could be encouraged to nest if eacis[ing wetlands and riparian woodlands on the pazk site aze pmtected and enhanced. ~ ~ ~ ~ Table 4. Breeding bird populations at Valmont Pazk and Coal Creek Open Space. Valmont Pazk Onlv Coal Creek Onlv Both Areas Swavvson's Hawk Red-tailed Hawk Mallazd Chimney Swift Spotted Sandpiper American Kestrel House Sparrow Common Snipe Killdeer Common Nighthawk Rock Dove Broad-tailed Hummingbird Mourning Dove Belted Kingfisher Great Homed Owl Downy Woodpecker Northem Flicker Western Kingbird Westem V/ood-Pewee Eastern Kingbud Rough-winged Swallow HornedLazk CliffSwallow Tree Swallow Blue Jay Violet-green Swallow Black-billed Magpie Barn Swallow Black-capped Chickadee Blue-gray Gnatcatcher House Wren Gray Catbird American Robin Cedar Waxwing European Stazling Yellow-breasted Chat Yellow Wazbler Black-headed Grosbeak Song Sparrow Blue Grosbeak Red-winged Blackbird C Lazuli Bunting Brewer's Blackbird Spotted Towhee Common Grackle Vesper Sparrow Brown-headed Cowbud Lark Sparrow Bullock's Oriole Grasshopper Sparrow House Finch Lesser Goldfinch American Goldfinch Species of Special Concem and Uncommon Species We observed no federal, state, or Boulder County avian species of special concem on the site between 20 May and 11 July. A previous study (Jones 2001) documented the presence on the site in winter of four Boulder County avian species of special concern: northern harrier, ferruginous hawk, golden eagle, and prairie falcon. Though these species may occasionally hunt over remaining grasslands on the pazk site, the site does not contain suitable nesting habitat for them We were surprised to find a faznily of Swainson's hawks (two adults and one juvenile) perching and flymg over the pazk site on 23 May. Swainson's hawks typically nest in relatively undisturbed eastern Colorado grasslands (Kingery 1998). We did not Snd a nest on the site but suspect that the adults were nesting somewhere neazby. This species was only recently removed from the Boulder Courny Avian Species of Special Concem list (Hallock and Jones 1999). ~ Ch~mney swifts aze uncommon breeders in Boulder Coumy (Boulder County Audubon Society ^ 1978-2001). Boulder lies at the western edge of their Great Plains breeding range (Kingery ~"e~ 1998). We observed chimney swifts in the northem portion of the park site during each of the three breeding bird surveys. Management Restoration and protection of existing riparian areas and grasslands on the Valmont Pazk site will benefrt habitat specialists such as Swainson's hawk, yellow warbler, and Bullock's oriole. In riparian corridors, retention of lazge trees, encouragement of shrub gowth, and buffering of riparian azeas &om recreational activities should contribute to nesting success of habitat specialists. Expansion of riparian corridors by tree and shrub plantings may reduce predation on habitat specialists by wban-adapted species. Linkage of existing riparian azeas through a network of wooded movement corridors will protect isolated nesting populations from the threat of being e~ctirpated by urban edge predators or by sudden environmental disturbances. In grasslands, promotion of native grass species and avoidance of habitat fragme~ation by trails and mads will help grassland specialists to nest successfully. Limited native shrub plantings in grasslands can provide additional cover and perch sites for western meadowlazks and sparrows. Future Reseazch Staff and I recommend that the seven pomt-count stahons established for this study be ~ permanently mazked and that breeding bvd counts be carried out three times annually, 20 May- 10 July, to track breeding bird populations as the park is developed. We recommend establishment of an eighth point-count station in the restored Wonderland Creek channel, appro~tely halfway between Valmont Road and the Goose Creek channel. Lrterature Cited Boulder County Audubon Society. 1978-2001. Boulder County wildlife inventories. P O. Box 2081, Boulder CO 80306. Ehrlich, P. R, D. S. Dobkin, and D. W. Wheye. 1988 The birder's handbook. Simon & Schuster, New York Hallock, D., and S. R Jones. 1999. Boulder County avian species of special concern. Boulder Cotwty Pazks and Open Space, P.O. Box 791, Boulder CO 80306. Jones, S. R 2001. Valmont City Pazk wildlife habitat assessment. City of Boulder Pazks and Recreation, P.O. Box 493, Boulder CO 80306. Kingery, H. E. 1998. Colorado breeding bird atlas. Colorado Breeding Bird Atlas Partnership, Denver. J 9 Appendix I: Plot Summazies ~ Plot 1 [Between irrigation ditches, northeast corner; 40 m northeast of ski trail sign] ~cies 23/5 15/6 11/7 Total Chimney Swift 1 1 W. Wood-Pewee 1 1 2 Blue Jay 1 1 Bl-billed Magpie 1 2 3 Bl-capped Chickadee 2 2 House Wren 1 1 American Robin 4 4 European Stazling 3 2 1 6 Song Sparrow 1 1 Westem Meadowlark 2 2 4 Brewer's Blackbird 1 9 10 Br-headed Cowbird 1 1 Bullock's Oriole 1 2 3 House Finch 1 1 2 Songbird species 1 1 3 5 ~ Species 7 7 7 14 Indrnduals 11 11 24 46 ~ 10 Plot No. 2 [Between irrigation ditches, northwest elm ~ tree at northeast comer of compost pile] Snecies 23/5 15/6 I1/7 Total Mallazd 1 1 Swainson's Hawk 1 1 American Kestrel 1 1 Mouming Dove 3 1 4 Chimney Swift 1 1 Northern Flicker 1 1 2 W. Wood-Pewee 1 1 Swallow species 1 Blue Jay 1 2 3 Bl-billed Magpie 2 2 2 5 Bl-capped Chickadee 1 House Wren 1 1 American Robin 1 1 2 European Starling 3 3 2 8 Song Spazrow 1 1 Western Meadowlark 2 2 1 5 Brewer's Blackbird 1 1 2 Common Grackle 3 3 Br-headed Cowbird 3 3 ^"~ Blackbird species 1 1 `"s Bullock's Oriole 2 2 1 5 House Finch 1 1 Songbvd species 2 1 3 Species 12 11 11 21 Individuals 23 19 15 57 ~ ii Plot No. 3 ~ [Plum thicket, north of Valmont; 30 m south of ~rrigation ditch] Snecies 23/5 15/6 11/7 Total B.C. Night Heron 1 1 Mallazd 2 2 American Kestrel 2 2 Rock Dove 7 7 Mouming Dove 3 3 Chvnney Swift 2 2 for W. Wood-Pewee 1 1 Swallow species 3 3 6 Blue Jay 1 1 Bl-billed Magpie 1 4 5 House Wren 1 1 2 American Robm 1 1 European Stazling 4 1 5 Song Spattow 1 1 Western Meadowlark 2 2 1 5 Brewer's Blackbird 4 3 7 Common Grackle 1 1 2 Br-headed Cowbird 1 1 2 ~ Bullock's Oriole 2 2 Songbud species 3 4 7 Species 10 9 9 19 Individuals 21 19 24 63 ~ 12 Plot No. 4 [Poplaz grove, south of Valmont; southwestem edge of grove] ~ S ies 23/5 15/6 11/7 Total American Kestrel 1 1 Rock Dove 6 6 R-winged Swallow 2 2 Cliff Swallow 1 1 Swallow species 5 5 Bl-billed Magpie 1 2 3 Amencan Robm 2 2 European Stazling 3 5 1 9 R-wwged Blackbird 2 2 Westem Meadowlark 2 1 1 4 Brewer's Blackbird 4 5 9 Common Grackle 3 2 5 Blackbird species 4 4 House Spazrow 2 1 3 Songbird species 1 1 Species 7 7 7 12 Individuals 18 20 19 57 ~ ~ 13 Plot No. 5 northeast comer of lar e mound] nce comer li k f ~ [Ch i n n e , a , g Suecies 23/5 15/6 11/7 Total Mallazd 1 1 2 Swainson's Hawk 1 1 Killdeer 1 1 2 Rock Dove 1 2 1 4 Northern Flicker 1 1 Cliff Swallow 2 5 7 Swallow species 3 3 Bl-billed Magpie 2 1 3 Common Raven 1 1 European Stazling 2 7 2 11 Westem Meadowlark 2 1 3 Brewer's Blackbird 1 2 3 6 House Finch 1 25 26 American Goldfinch 1 1 Songbird species 4 4 Species 11 9 6 13 Individuals 15 23 37 75 ~r.~ ~ 14 Plot No. 6 [Goose Creek/Wonderland Creek confluence; 30 m north of b~1ce trail] ~ S~ecies 23/5 15/6 11/7 Total Rock Dove 3 3 Cliff Swallow 8 8 Swallow species 1 5 6 Bl-billed Magpie 3 1 4 European Stazling 3 1 3 7 Western Meadowlark 3 1 2 6 Brewer's Blackbird 1 1 2 Common Grackle 2 1 3 House Finch 2 2 House Sparrow 1 1 1 3 Species 5 7 8 10 Individuals 10 13 21 44 ~ ~ 15 Plot 7 ~ [Knoll, south of Valmont; 20 m southwest of lone cottonwood] S~ecies 23/5 15/6 11/7 Total Mallazd 1 1 American Kestrel 1 2 3 Mouming Dove 2 2 4 Northern Fhcker 1 1 Woodpecker species 1 1 Swallow species 5 2 7 Blue Jay 1 1 2 Bl-billed Magpie 1 6 1 8 American Robin 1 1 European Starling 4 6 10 Yellow Wazbler 1 1 Western Meadowlark 1 1 1 3 Brewer's Blackbird 3 4 7 Common Grackle 1 1 Blackbird species 5 5 House Finch 4 3 7 American Goldfinch 1 1 ~ House Spaztow Son bird s ecies 1 1 1 1 g p Species 8 9 11 16 Individuals 13 29 23 65 ~