The osprey (Pandion haliaetus) is a large bird of prey that is found on every continent except Antarctica. Ospreys are known for their ability to hunt live fish by diving into water feet first. They have several adaptations that help them catch fish, including reversible outer toes, closable nostrils to keep out water, and backwards facing scales on their talons to help grip slippery fish.
Ospreys build large nests high up on platforms near water, where they raise their young. Though ospreys are found in many habitats globally, they thrive around clean rivers, lakes, and coastal areas that provide ample fish. Their wide distribution is due to their ability to migrate long distances between breeding and wintering grounds.
Phoenix, located in the Sonoran Desert of central Arizona, may seem an unlikely place to find ospreys given its hot, dry climate and distance from significant bodies of water. However, ospreys have been documented around some desert oasis habitats with fish-stocked lakes. This article explores the evidence for ospreys in Phoenix and discusses the habitats where they might occur.
Do Ospreys Live in Phoenix?
While not common, there are some documented occurrences of ospreys around the greater Phoenix metropolitan area. According to citizen science observations, ospreys have been spotted at desert lakes including Lake Pleasant, Saguaro Lake, Canyon Lake, Apache Lake, and Theodore Roosevelt Lake.
Most sightings occur during spring and fall migration, when ospreys move through Arizona on their way between summer breeding grounds farther north and wintering grounds in Central and South America. Some individual ospreys likely stop to rest and feed for short periods along these migration routes.
A few ospreys have also been observed during summer months, indicating they may occasionally nest in the area. In 2006, a pair of ospreys was documented nesting at Lake Pleasant and successfully raising two chicks. This was the first confirmed osprey nest in Maricopa County. Since then, summer residents have also been observed at Saguaro Lake.
So while not a permanent resident, evidence shows ospreys do occasionally inhabit the Phoenix area, especially larger desert lakes. Their presence is enabled by fish stocking programs that provide a food source.
Osprey Habitats in Phoenix
If ospreys are found around Phoenix, what specific habitats do they use? Here are details on the main lakes and rivers where ospreys have been observed in and near the city:
Lake Pleasant
Lake Pleasant is a 10,000 acre reservoir on the Agua Fria River in Maricopa County, about 30 miles northwest of downtown Phoenix. It was created by the construction of New Waddell Dam in 1927. As Arizona’s largest reservoir, Lake Pleasant provides flood control, water storage, and recreational opportunities.
The lake is stocked with desirable fish for ospreys including rainbow trout, largemouth bass, sunfish, and carp. The stocking program provides a food source that makes the area habitable for ospreys. There is also ample shoreline and trees suitable for building nests. Several nest platforms have been installed to provide additional nesting sites.
With fish present, Lake Pleasant likely represents the best osprey habitat in the Phoenix region. The area’s first confirmed osprey nesting occurred here in 2006, and migrants regularly stop over on journeys between more northerly breeding grounds.
Saguaro Lake
Saguaro Lake is an 1,800 acre reservoir on the Salt River northeast of Phoenix, created by the Stewart Mountain Dam. Located within the Tonto National Forest, it offers recreational fishing as well as desert scenery. Largemouth bass, sunfish, catfish, and carp have been stocked in the lake.
The presence of fish makes Saguaro Lake a regularly used stopover point for migrating ospreys in spring and fall. A few summer residents and nest attempts have also been recorded, including confirmed nestings in 2011 and 2013. There are ideal nesting sites on the rugged cliffs surrounding the lake.
Canyon Lake
Canyon Lake is an 825 acre reservoir on the Salt River about 50 miles northeast of Phoenix. It was formed by Mormon Flat Dam, completed in 1925. Canyon Lake is a popular recreation destination within Tonto National Forest. It is stocked with rainbow trout, bass, sunfish, and catfish.
There are few documented osprey sightings at Canyon Lake, but its proximity to Saguaro Lake and available fish suggest ospreys likely stop there on occasion, especially during migrations. The steep terrain offers potential nesting sites if any ospreys took up residence.
Roosevelt Lake
Theodore Roosevelt Lake is a large reservoir on the Salt River formed by Theodore Roosevelt Dam. It has a surface area of 15,000 acres but fluctuates based on water levels. Located 75 miles northeast of Phoenix, it provides hydroelectric power in addition to water storage and recreation.
Roosevelt Lake has a healthy fishery including largemouth bass, sunfish, channel catfish, flathead catfish, and rainbow trout. There are documented observations of ospreys stopping over at the lake during migrations. Nesting potential appears limited due to scarce trees and cliffs, but the abundant fish make it a reliable food source on migration routes.
Apache and Canyon Lakes
Other smaller lakes northeast of Phoenix where transient ospreys have been documented include Apache Lake and Horse Mesa Lake. Their distance from Phoenix makes them unlikely habitats for nesters, but migrants probably stop opportunistically at these lakes during journeys between more established osprey breeding and wintering grounds.
Verde and Salt Rivers
There are a few records of ospreys along the Verde and Salt Rivers, which provide natural flows into reservoirs like Roosevelt and Canyon Lakes. However, wild sections of these rivers lack significant standing water suitable for fishing. Most osprey activity occurs at river sections impounded into reservoirs with abundant stocked fish.
Osprey Nesting and Conservation
While migrating ospreys occasionally pass through the Phoenix region, evidence suggests nesting attempts are rare and likely unsuccessful most years. There are considerable challenges for ospreys establishing permanent breeding territories in the area.
Nesting Habitat Limitations
The desert lakes near Phoenix have adequate fish populations, but lack extensive shoreline trees suitable for nesting. Ospreys build bulky nests up to six feet wide, typically in a tree fork 20-150 feet above ground. Many desert lakes are surrounded by sparser desert scrub vegetation not ideal for nest support.
Artificial nesting platforms have enhanced habitat at some lakes like Lake Pleasant, but most of the area lacks sufficient natural nesting substrates. Lake drawdowns during drought may also impact nest sites.
Heat Stress
Phoenix’s hot summer temperatures pose challenges for osprey chick survival. Average highs from May to September range from 95-106°F in Phoenix, sometimes spiking above 110°F. Studies show temperatures over 100°F can cause heat stress for osprey chicks. Such overheating may be a factor limiting reproductive success and permanent residency in the Phoenix climate.
Limited Breeding Sites
Given the scarcity of ideal nesting habitat and potentially high heat stress, it appears relatively few sites in the Phoenix area are suitable for osprey breeding. Lake Pleasant likely offers the best conditions with cooler temperatures, nest platforms, and protected status. But most desert lakes have limitations preventing large stable nesting populations. More research is needed on the requirements for maintaining osprey breeding territories in desert environments.
Conservation Efforts
While not a conservation priority species in Arizona, efforts to support ospreys around Phoenix lakes could allow small numbers to persist. These include:
– Installing artificial nest platforms where needed
– Protecting known nest trees and maintaining lake levels during nesting season
– Stocking fish to provide adequate food
– Limiting human disturbance around nest sites during breeding season
– Managing recreation to minimize impact on shoreline habitat
With human help addressing habitat needs, ospreys may continue to occupy a small desert niche in the region. But the naturally limited habitat means large permanent populations are unlikely. Phoenix will probably remain just one stop on the migratory journeys of this widespread raptor.
Conclusion
In conclusion, ospreys do inhabit the Phoenix metropolitan area, especially around several desert reservoirs. However, their presence is mainly transitory during spring and fall migrations, with just occasional summer nesting. Suitable nesting habitat is scarce, limiting the potential for permanent breeding territories. But fish stocking creates reliable stopover points with ample food. Conservation efforts focused on adding nest platforms may allow small numbers of ospreys to persist, but the desert ecosystem likely cannot support large resident populations. With supplemental habitat management, Phoenix reservoirs will continue to provide outposts for this versatile raptor at the southern fringe of its North American range.