Point-count bird censusing: long-term monitoring of bird abundance and diversity in central Arizona-Phoenix, ongoing since 2000

Project overview : Over the past half-century, the greater Phoenix
metropolitan area (GPMA) has been one of the fastest growing regions in the US, experiencing
rapid urban expansion in addition to urban intensification. This backdrop provides an ideal
setting to monitor biodiversity changes in response to urbanization, and the CAP LTER has
been using a standardized point-count protocol to monitor the bird community in the GPMA and
surrounding Sonoran desert region since 2000. The bird survey locations in this CAP LTER core monitoring program include four general site groupings : 1. ESCA. Forty bird survey locations were selected from a subset of the CAP LTER's
Ecological Survey of Central Arizona (ESCA; formerly named Survey200) long-term monitoring
sites. ESCA sites were located using a tessellation-stratified dual-density sampling design,
and, as such, span a diversity of habitats including urban, suburban, rural, commercial
areas, parks, agricultural fields, and native Sonoran desert. Earlier versions of this data
package included data from the ESCA project that was intended to compliment the bird data.
However, while positioned in close proximity, the bird survey locations do not necessarily
overlap with the 30m X 30m plot that constitutes an ESCA sampling location, and leveraging
data from these two monitoring programs should be addressed carefully. ESCA data have
corresponding survey location names, and those data are available through the CAP LTER and
LTER network data portals. 2. North Desert Village (NDV). Additional bird survey locations were positioned in
treatment areas of the North Desert Village (NDV). This was a site of intense study on the
Arizona State University Polytechnic Campus in which the CAP LTER converted the landscaping
of small neighborhoods to reflect the dominant landscaping preferences employed throughout
the GPMA. NDV landscape types include: oasis (NDV-O), xeric (NDV-X), mesic (NDV-M), control
(NDV-C), and native (NDV-N). 3. Riparian. While the forty bird survey locations that were selected to coincide with
ESCA sampling locations span a wide diversity of habitats throughout the GPMA, because of
the generally random nature of selecting those sites, they did not reflect riparian
habitats. Riparian areas are important bird habitat but constitute a very small area of the
GPMA. To address this deficiency, bird survey locations were established specifically in
twelve riparian habitats. Riparian habitat sub-types include: (1) ephemeral-engineered (EE,
n=4), (2) ephemeral-natural (EN, n=2), (3) perennial-engineered (PE, n=3), and (4)
perennial-natural (PN, n=3). 4. Salt River. Study sites along the Salt River as it runs through the GPMA that were
selected as part of a related study (Salt River Biodiversity Project (SRBP)) were ultimately
included in the CAP LTER's core bird monitoring programs. These sites reflect additional
riparian habitat. Method overview : In a given season, each bird survey location is
visited independently by three birders who count all birds seen or heard within a 15-minute
window. The frequency of surveys has varied through the life of the project. The first year
of the project (2000) was generally a pilot year in which each site was visited
approximately twice by a varying number of birders. The monitoring became more formalized
beginning in 2001, and each site was visited in each of four seasons by three birders. The
frequency of visits was reduced to three seasons in 2005, and to two season (spring, winter)
beginning in 2006.