2016 Breeding Bird Survey Report, Lawton Farm Recreation Area, Scituate Rhode Island

Transcription

1 2016 Breeding Bird Survey Report, Lawton Farm Recreation Area, Scituate Rhode Island Prepared for: Scituate Conservation Commission Clara Cooper-Mullin and Richard McKinney September 2016

2 1. Executive Summary: This report describes the results of a series of breeding bird point count surveys conducted at the Lawton Farm Recreation Area in Scituate, Rhode Island between May and June To identify breeding birds and evaluate habitat preferences of different species, point count surveys were conducted at three sites within Lawton Farm representing shrubland, forest, and field habitats. In general, surveys results in 2016 were similar in species richness, but showed a substantial increase in overall bird abundance when compared to surveys conducted from Highlights of the 2016 survey results are listed below: 1) We observed 28 unique bird species across the three sites during the three survey periods. The five most abundant species were bobolink, American goldfinch, American robin, blue jay, and Eastern towhee. 2) The total species richness recorded this year (38) was the highest recorded since this survey effort began in 2012, three higher than the next highest recorded in Over the five consecutive years that this series of surveys has been carried out, a total of 61 unique species have been recorded at Lawton Farm. 3) Bobolinks continue to be observed at Lawton Farm in substantial numbers in Field 1. Unlike previous surveys where they were primarily observed in Fields 1 and 2, this year bobolink were also observed in Field 3. 4) Total abundance across all sites in 2016 was 207 individuals, much greater than the next highest total of 133 individuals observed in 2014, and an increase over the average of 111 individuals per year reported over the previous 4 years. 5) Twelve shrubland species were observed in surveys this year, and a total of 21 shrubland species have been reported over the five consecutive survey years ( ). These findings suggest that Lawton Farm is providing important habitat for shrubland species. Lawton Farm provides a number of unique habitats to a variety of bird species, and thus contributes to maintaining regional bird diversity within New England. From a conservation point of view this is extremely valuable as this area is helping to maintain and enhance local and regional biodiversity. The property is particularly important to shrubland species and a single grassland species, since both categories of birds have suffered regional declines due to habitat loss and forest succession in recent years. Suggested citation: Cooper-Mullin, C., and R. McKinney Breeding Bird Habitat Report, Lawton Farm Recreation Area, Scituate Rhode Island. Department of Natural Resources Science, University of Rhode Island, Kingston, Rhode Island. For more information contact Clara Cooper-Mullin (chelseaglinka@gmail.com) or Richard McKinney (rmckinney@uri.edu).

3 2. Introduction This report describes the results of a series of breeding bird point count surveys conducted at the Lawton Farm Recreation Area in Scituate, Rhode Island between May and June Lawton Farm is a 54.4 acre parcel consisting primarily of open fields and shrubland, except for approximately 20 acres of forested wetlands and a small stand of upland hardwoods in the southwest corner. The ownership of the property is divided between the Scituate Land Trust, which purchased 39.4 acres (plat 9-1, lot 9) of the property via a conservation easement in 1990 through an Open Space Grant from the Rhode Island Department of Environmental Management (RIDEM), and the Town of Scituate, which purchased the remaining 15 acres (plat 9-1, lot 272) the same year (Town of Scituate, Real Estate Data). The 15 acres owned by the Town does not have a conservation easement or any other type of protection that would prevent development. The Scituate Town Council has assigned the task of managing the Lawton Farm property to the Scituate Conservation Commission (SCC). The SCC is an advisory board that works to promote and develop natural resources, protect watershed resources, and to preserve natural aesthetic areas within the Town of Scituate (Town of Scituate). A property management plan for Lawton Farm was developed in and the SCC continues to implement the conservation and management objectives described within the plan. An important objective for the property is to maintain grassland habitat for the bobolink (Dolichonyx oryzivorous) and eastern meadowlark (Sturnella magna). To evaluate the progress of this management objective and to better understand bird use of the valuable shrub and grassland habitat that the property offers, point count surveys have been conducted since This report provides results of the fifth consecutive year of point count surveys at Lawton Farm. 3. Methods The 2016 point count surveys were conducted at the same sites used in the surveys. The three sites were selected based on the different types of shrubland in addition to forest and field habitats (Table 1 and Figure 1). Table 1: Lawton Farm point count site habitat descriptions 2016 Site Description Site 1 Field with periodic mowing, forested perimeter Site 2 Field, shrubland and forest on perimeter Site 3 Shrubland created by irregular mowing of the field, a meadow, and forest

4 Figure 1: Point count sampling sites at Lawton Farm, Scituate, Rhode Island in These sites are the same as the point counts conducted from Site 1: The first survey site was located in the central portion of the property on the edge of Field 1 (Figure 1; o N, o W, Figure 2). The field was bordered by small patches of shrubland to the north and west. This site included a hedgerow of mature trees

5 which was removed in 2012 to connect Fields 1 and 2 to improve habitat for bobolink and other grassland bird species. The eastern portion of the shrubland was dominated by multiflora rose (Rosa multiflora), which transitioned into a small herbaceous wetland to the west. To the north of the shrubland was a small area of forest where red maple (Acer rubrum) and white ash (Fraxinus americana) are the dominant species. To the east and south of the sampling site was Field 1, which is mowed every other year to maintain grassland habitat; mowing occurs in September to prevent disturbance of nesting birds. The hay bales are sold as construction hay. Figure 2: A view of Site 1 looking southerly with field 1 to the left. In an effort to improve nesting habitat for grassland species, this year some of the walking trails have been closed and allowed to naturally re-vegetate. The former walking path is just barely evident in the middle of the photo. Site 2: The second sampling site was located in the western portion of the property on the southwestern edge of Field 3 ( o N, o W) adjacent to a patch of shrubland which began management in 2012 for invasive plant removal of species such as autumn olive (Elaeagnus umbellate) multiflora rose. Prominent species in this area included saplings of black cherry (Prunus serotina), Oriental bittersweet (Celastrus orbiculatus), and poison ivy (Toxicodendron radicans). The sampling site also included upland forest dominated by white ash and white oak (Quercus alba) (Figure 3).

6 Figure 3. A view of Site 2 looking northwest. Site 3: The third sampling site was located in the northern boundary of the property on the northern edge of Field 4 ( o N, o W). Field 4 included patchy regeneration of saplings of black cherry, American ash, and white oak. This sampling site provided the most heterogeneous vegetation mixture which contained short grasses and forbs interspersed with shrubs that measure up to four feet tall (Figure 4). White oak and American ash were the dominant species within the upland forest located on the northern limits of the survey site.

7 Figure 4. A south-facing view of the heterogeneous shrub habitat at Site 3. The forested line in the background divides this site from Site 2. The methodology used in the 2016 point count surveys followed the same protocol used in the surveys. The purpose of the point count surveys was to identify breeding birds within Lawton Farm and to evaluate habitat preferences of different species. The three selected survey sites were separated by a distance of greater than 100 m to minimize the possibility recording the same bird at more than one site. Point counts were preceded by a three minute wait period in order to minimize the disturbance to birds and to allow them to acclimate to the observers presence. Point counts were conducted by a primary observer facing south (R. McKinney) and a secondary observer facing north (C Cooper-Mullin) in order to achieve a 360º view of the site. Species identification and abundance were recorded based on songs, calls, direct observations, and fly overs within 100 m of the observation site during each ten minute point count. Observers made distinctions between birds present 50 m from the site and those between 50 and 100 m from the site. Observers communicated to avoid recording the same bird twice and to clarify location and species. All data was recorded by one observer (R. McKinney) to keep the notes about birds consistent. Each site was surveyed on three separate occasions on May 23rd, June 10th and 27th, 2016 and all were conducted between 0630 and 0830 hours. 4. Results We observed 38 unique bird species in 2016 across the three sites during the three survey periods. The most abundant species were bobolink (Dolichonyx oryzivorus; 34

8 records), American goldfinch (Carduelis tristis; 15 records), American robin (Turdus migratorius; 13 records), blue jay (Cyanocitta cristata;13 records) and Eastern towhee (Pipilo erythrophthalmus; 14 records). Other prominent species, each with 5 records, were blue-winged warbler (Vermivora cyanoptera), Canada goose (Branta canadensis), common grackle (Quiscalus quiscula), field sparrow (Spizella pusilla), indigo bunting (Passerina cyanea), mourning dove (Zenaida macroura), Northern cardinal (Cardinalis cardinalis), redwinged blackbird (Agelaius phoeniceus), red-bellied woodpecker (Melanerpes carolinus), song sparrow (Melospiza melodia) and yellow warbler (Setophaga petechia) (Table 3). Bobolinks continue to be observed at Lawton Farm in substantial numbers in Field 1 where they nest and use the area for foraging and cover. Unlike the previous surveys, this year bobolink were also observed at Site 2, but later in the season and in smaller numbers than at Site 1 which boasts a large amount of suitable grassland habitat for bobolink. Over the five consecutive years that this series of surveys has been carried out, a total of 61 unique species have been recorded at Lawton Farm. The total species richness recorded this year (38) was the highest recorded to date, surpassing that of the previous 4 years: 2015 (32), 2014 (35), 2013 (25), and 2012 (28). Site 1 had 6 species recorded that were not observed at other sites (common grackle; yellow warbler; black-throated blue warbler (Setophaga caerulescens), European starling (Sturnus vulgaris), red-winged blackbird, tree swallow). Site 2 had 6 species not recorded at the other sites (common yellowthroat, prairie warbler, rose-breasted grosbeak (Pheucticus ludovicianus), indigo bunting; ovenbird (Seiurus aurocapilla), black-throated green warbler (Setophaga virens)). Site 3 had 7 species not observed at other sites (Eastern phoebe (Sayornis phoebe), Eastern wood-pewee (Contopus virens), field sparrow; house wren, brown headed cowbird (Molothrus ater), chipping sparrow (Spizella passerina), rubythroated hummingbird (Archilochus colubris)). Only 4 species were recorded at all sites (Northern cardinal, red-eyed vireo, eastern towhee, blue jay), although many were represented at two out of the three sites (Table 3). The greatest number of species recorded during a count was on 6/27/16 at Site 3 (16 species). Three species were observed on the property during the 5/23/16 sample event, but seen outside of the sample site locations: great blue heron (Ardea herodias), Northern flicker (Colaptes auratus), and wood thrush (Hylocichla mustelina). An American kestrel (Falco sparverius) was observed outside the count sites on 6/10/16. Additionally, there were several species counted during the earliest count date (5/23/16) that were assumed to be migrants and therefore not included in the larger breeding bird survey data. These species were warbling vireo (Vireo gilvus; Site 1), blackpoll warbler (Dendroica striata; Site 2), and Northern parula (Parula americana; Site 2). Total abundance across all sites in 2016 was 207 individuals, much larger than both the 132 individuals observed in 2015, and 133 observed in 2014 (Table 3). In 2016, the greatest number of individuals recorded in a count within 100 m of the site occurred on 6/27/16 at Site 1 (33 individuals). Within that count, bobolink (Dolichonyx oryzivorus) was the highest (14 individuals recorded), followed by red-winged blackbirds (Agelaius phoeniceus) (5 individuals recorded)).

9 Table 2: Number of individual birds counted and the number of species counted at all 3 Lawton Farm point count sites by date Date Number of Individuals Number of Species 5/23/ /10/ /27/ The number of species and individuals seen during the point counts increased as the season progressed (Table 2). Only one species, the rose-breasted grosbeak (Pheucticus ludovicianus) was seen on 5/23/16 that was not seen during the other counts. Four species (black-throated blue warbler (Setophaga caerulescens), European starling (Sturnus vulgaris), tree swallow (Tachycineta bicolor), and house wren (Troglodytes aedon) were seen on 6/10/16 that were not seen during the other counts. Eight species (American goldfinch, blackcapped chickadee (Poecile atricapillus), gray catbird (Dumetella carolinensis), ovenbird (Seiurus aurocapilla), black-throated green warbler (Setophaga virens), brown headed cowbird, chipping sparrow, and ruby-throated hummingbird) were seen on 6/27/16 and not observed during the other count dates. Twelve of the species seen during the 2016 counts were shrubland birds, but the bobolink was the only grassland species (Table 3). Indigo bunting (Passerina cyanea), a species dependent on shrubland habitat. Table 3. Abundance of bird species observed within 100 m of the point count center during 10 minute counts at three sites within Lawton Farm Recreation Area, Scituate, Rhode Island, in 2012, 2013, 2014, 2015, and Observations were based on singing, calls, visual observation, and fly overs. Those species marked with an asterisk are designated as core shrubland species in New England (Schlossberg and King 2007). Those marked with a double asterisk are designated as grassland species (Natural Resource Conservation Service 1999).

10 Common Name Scientific Name Shrubland Site 1 Site 2 Site 3 Site 1 Site 2 Site 3 Site 1 Site 2 Site 3 Site 1 Site 2 Site 3 Lawton 1 Lawton 2 Lawton 3 American crow Corvus brachyrhynchos American goldfinch* Carduelis tristis Yes American robin Turdus migratorius Baltimore oriole Icterus galbula Barn swallow Hirundo rustica Black-capped chickadee Poecile atricapilla Black-throated blue warbler Dendroica caerulescens Black-throated green warbler Setophaga virens Blue Jay Cyanocitta cristata Blue-winged warbler* Vermivora pinus Yes Bobolink** Dilichonyx oryzivorus Brown headed cowbird Molothrus ater Brown thrasher* Toxostoma rufum Canada goose Branta canadensis Carolina wren* Thryothorus ludovicianus Cedar waxwing* Bombycilla cedorum Chestnut-sided warbler* Dendroica pensylvanica Chipping sparrow Spizella passerine Common grackle Quiscalus quiscula Common yellowthroat* Geothlypis trichas Yes Downy woodpecker Picoides pubescens Eastern kingbird Tyrannus tyrannus Eastern phoebe Sayornis phoebe Eastern towhee* Pipilo erythrophthalmus Yes Eastern wood-pewee Contopus virens European starling Sturnus vulgaris Field sparrow* Spizella pusilla Yes Gray catbird* Dumetella carolinensis Yes Great crested flycatcher Myiarchus crinitus Hairy woodpecker Picoides villosus House finch Carpodacus mexicanus House sparrow Passer domesticus House wren* Troglodytes aedon Yes Indigo bunting* Passerina cyanea Yes Magnolia warbler* Dendroica magnolia Mallard Anas platyrhynchos Mourning dove Zenaida macroura Northern cardinal* Cardinalis cardinalis Yes Northern flicker Colaptes auratus Northern mockingbird* Mimus polyglottos Ovenbird Seiurus aurocapillus Palm warbler* Dendroica palmarum Prairie warbler* Dendroica discolor Yes Red-bellied woodpecker Melanerpes carolinus Red-eyed vireo Vireo olivaceus Red-winged blackbird Agelaius phoeniceus Ring-necked pheasant** Phasianus colchicus Rose-breasted grosbeak Pheucticus ludovicianus Ruby-throated hummingbird Archilochus colubris Scarlet tanager Piranga olivacea Song sparrow* Melospiza melodia Yes Tree swallow Tachycineta bicolor Tufted titmouse Baeolophus bicolor Veery Catharus fuscescens White-breasted nuthatch Sitta carolinensis Wild turkey Meleagris gallopavo Willow flycatcher* Empidonax traillii Wood thrush Hylocichla musteling Yellow warbler* Dendroica petechia Yes Yellow-billed cuckoo* Coccyzus americanus Total Abundance

11 5. Discussion The number of species recorded was the highest observed to date and confirms that the Lawton Farm Recreation Area, with its grassland, shrubland, and forest habitats, is consistently supporting a diverse group of bird species. Lawton is a unique property in the region because its three important bird habitat types are located in relatively close proximity to each other, which results in a rich assortment of bird species. This enhances the value of this land for bird conservation. Bird abundance and species richness has trended towards increasing over the 5 years of surveys that have been conducted. This is a good indication that management practices are continuing to provide important habitat, and it is encouraging that there have been no declines of any particular group of species. We did observe several species in 2016 that had not been observed previously, but there were also species that had been observed in the past that were not observed this year. This is normal in any given area, as local populations of some species relocate and other species move in. The large number of migrant (non-breeding) birds observed in 2016 may have resulted from a combination of a somewhat late spring migration with the timing of our first survey, which was a little earlier than in the past. The presence of migrant species, stopping over on their way to their breeding grounds in the northern US and Canada, also testifies to the importance of Lawton s habitats to overall bird conservation. Field 1 at Lawton supports a large population of breeding bobolinks, a RI state listed Species of Greatest Conservation Need. This is a significant contribution to the regional conservation of grassland birds, particularly in light of recent losses in grassland bird habitat in the northeast US largely due to the decline of the agricultural industry (U.S. Department of Agriculture 2010). The current management of Field 1 is clearly helping to promote bobolink habitat and should continue. Until this year bobolink have not been observed elsewhere in the property during official point count surveys, although some individuals were observed outside of the survey period in Field 2 in 2014 and 2015, which suggests that management practices designed to enhance grassland bird nesting habitat (i.e., removal of the hedgerow of mature trees in 2012 in order to connect Fields 1 and 2) may be having a positive impact. Bobolink observed in Field 3 this year may have been fledglings that were searching for territories, or mature adults that were following and feeding fledglings. In either case this is a positive sign that the bobolink population at Lawton is doing well. Lawton also continues to support a significant number of shrubland bird species, several of which are also RI state listed Species of Greatest Conservation Need. This is also an important contribution to regional bird conservation, particularly in light of the fact that shrubland habitats in the northeast US are at or near historic lows (King and Schlossberg 2012). Our observations verify that Lawton Farm is well suited for shrubland species. We suggest that management practices that control the successional growth of woody vegetation be continued in areas that are currently shrubland. Lawton Farm continues to provide a number of unique habitats to a variety of bird species. From a conservation point of view this is extremely valuable as Lawton Farm is helping to maintain and enhance local and regional biodiversity. The property is particularly important to shrubland species and a single grassland species, with both categories of birds suffering declines due to habitat loss and forest succession in recent years. Based on the habitat loss these species are experiencing, it is important to maintain grassland and shrubland habitat at the site. We recommend several management strategies, some of which are already being employed, that can maximize the conservation value of Lawton Farm to grassland and shrubland species:

12 1.) Mowing Fields 1 & 2 everyone one to three years after mid-august to ensure that birds have completed their nesting cycle. 2.) Removal of edge habitat; both shrubland and grassland species avoid edges and Lawton Farm s fields are fragmented by thin forest stands. 3.) Control the successional growth of woody vegetation; this may be a difficult balance to strike since grassland species decline in areas after woody shrubs have taken hold and shrubland species preferences are wider ranging. 4.) Ensure that people and pets who recreate at Lawton Farm stay on the trails during the spring and summer to avoid disturbing nesting birds. Since most shrubland and grassland birds nest on the ground they are particularly vulnerable to disturbance. Creating signs that clearly state when pets are allowed and not allowed on the property, and the rules regulating pets could help to curtail the negative effects dogs and other pets have on nesting birds. Overall the surveys conducted this year indicate that the diversity and abundance of birds nesting and foraging at Lawton Farm have been maintained at or above levels recording over the previous 4 years of surveys. This is very encouraging and highlights the positive contribution Lawton is providing for regional bird conservation. Management actions should continue to help maintain the important bird habitats found at Lawton, and we also recommend that future annual bird surveys be continue to be able to identify any changes in bird use of the area. Literature Cited King, D.I., Schlossberg S.R Conservation practices benefit shrubland birds in New England. Conservation Effects Assessment Project, Natural Resources Conservation Service. United States Department of Agriculture, Natural Resource Conservation Service Management considerations for grassland birds in northeastern haylands and pasturelands. Wildlife Insight. Washington, DC.