Greater Phoenix Area Waterbird Survey

Annual event typically held on the third Saturday of January

Photo/Barb Winterfield

It has long been noted that wintering waterbirds concentrate in exceptional numbers in several highly urban water sources in the Phoenix metropolitan area. The greater Phoenix area is one of the fastest growing regions of the United States and additional lakes and ponds continue to be constructed in new residential neighborhoods and golf courses throughout the area attracting even more wintering aquatic birds. To clarify, waterbirds are noted as wild geese, ducks, cormorants, grebes, coots, rails, egrets, herons, bitterns, shorebirds and several fish-eating birds such as Bald Eagles, Ospreys, and Belted Kingfishers.

It became apparent in recent years that only a small sampling of these numerous, urban water bodies are regularly visited by birders and fewer still are included in local Christmas Bird Count circles (Figure 1) to document annual numbers. As part of the implementation of the Arizona Coordinated Bird Monitoring Program sponsored by the Arizona Bird Conservation Initiative, a preliminary survey of some key urban areas was conducted by seven surveyors on 21 January 2006. Even with this limited efforts, it was determined that this extensive urban area likely held a significant density of wintering aquatic birds that previously had not been realized.

Figure1. Greater Phoenix area city and Christmas Bird Count boundaries with water body locations depicted.

There are many factors that likely contribute to the tremendous density and diversity of wintering aquatic birds to the highly urbanized greater Phoenix area. These include the abundant supply of unfrozen water bodies in this otherwise dry, southwest desert location and a safe haven from hunting pressure. Many lakes and ponds are located within manicured parks and golf coursed readily providing fresh green grass (winter rye) throughout the winter for abundant grazing species such as American Coots and American Wigeons. Many additional waterbirds are attracted to the locally high concentration of fish, mollusks, and crustaceans. Adjacent agricultural lands also provide foraging areas for flocks of geese and Cattle Egrets which roost and loaf at urban lakes and ponds.

Since the 2006 preliminary survey, this single-day census is now conducted annually on the third Saturday of January by over 65 volunteers. This census has documented 40,000-65,000 wild waterbirds of 50-60 species wintering in this otherwise desert urban area. The survey area encompasses 26 cities within the metro area and over 50 square miles. In comparable size, there is no other location in Arizona with this high of diversity and density of wintering waterbirds. Individual surveyors or teams are assigned a specific city area which can be successfully surveyed that day (Figure 2).  Within assigned area, surveyors visit all water bodies with safe and reasonable viewing access. Surveyors must annually obtain official permission before entering any signed restricted or closed areas, such as gated communities, resorts and golf courses. Most water bodies are highlighted in blue on maps provided.

Figure 2. Greater Phoenix Area Waterbird Census survey areas and water bodies.

Survey results not only assist in monitoring annual winter populations, but also identify high concentration areas and/or species richness locations. High concentration of certain species may locally lead to potential urban management conflict areas. These include concentrations of cormorants at urban fishing sites stocked with fish and turf damaged and soiling caused by grazing species such as American Coots and American Wigeon on golf courses and in parks. Potential future urban wildlife viewing areas are also being highlighted through these surveys.