### 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 six 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 complement 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. At the
conclusion of the 2016 spring survey, fifteen of the ESCA-correlated
sites were discontinued as the core monitoring program refocused its
efforts on desert parks and PASS neighborhoods. Among the deleted
locations were all agricultural and commercial sites, as well as
sites where access had become restrictive.
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). Monitoring at NDV was discontinued
after the spring 2016 season as research efforts at this site came
to an end.
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). This research was
successfully concluded and these sites were discontinued after the
spring 2016 season.
4. Salt River. Seven 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
continued monitoring of riparian habitat.
5. Desert Fertilization. Beginning with the 2016-2017 winter survey,
six sites at desert parks were added to core monitoring to coincide
with the CAP LTER Desert Fertilization (DesFert) experiment sites.
6. PASS. Beginning with the 2016-2017 winter survey, what used to be a
separate bird-monitoring effort (monitoring in Phoenix Area Social
Survey (PASS) neighborhoods) was incorporated into this core
bird-monitoring program. Eight points were carried over from prior
PASS monitoring, and 28 new points established, resulting in three
bird monitoring locations in each of the twelve PASS neighborhoods.
Visiting these locations each year, versus only in years surrounding
the PASS survey as done previously, provides more data on bird
populations found in the neighborhoods of the CAP LTER study area.
### 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.
