In collaboration with the U.S. Geological Survey Colorado Plateau Field Station, the Ecological Monitoring & Assessment (EMA) Program completed an avian survey of the upper reaches of Fossil Creek in early 2005. Released in October 2005, the final report was prepared by Chris Calvo, Matthew Johnson, and Jennifer Holmes and entitled “Common Black-Hawk and Yellow-billed Cuckoo distribution and abundance in the upper reach of Fossil Creek, AZ, 2005.” The Yellow-billed Cuckoo and the Common Black Hawk were selected as part of the Fossil Creek Faunal Monitoring Program associated with the decommissioning of the Childs and Irving Power Plants downstream of the Fossil Springs Diversion Dam.

Common Black Hawk
The Common Black Hawk is an obligate riparian nester that favors remote, mature gallery forest corridors along perennial streams. The Common Black Hawk’s breeding habitat ranges from northern South America to southwestern Utah; it is a migratory species in the United States and generally resides elsewhere. While the Common Black Hawk is not a federally listed endangered species, it is recognized as threatened in Texas, endangered in New Mexico and of concern (a “candidate species”) in Arizona. It is considered to be a Management Indicator Species in the Tonto and Coconino National Forest Plans and is on the Regional Forester’s Sensitive Species List. The population status of the Common Black Hawk is currently unknown; further research is needed throughout its range.

Researchers conducted the surveys between March 1st and June 13th, 2005 along the riparian corridor 0.5 miles upstream of the Fossil Springs Diversion Dam and 0.5 miles downstream of the Childs and Irving Power Plants. The five formal surveys and three informal surveys (incidental surveys conducted during the cuckoo surveys) resulted in 32 Common Black Hawk detections and four active nests. The researchers confirmed that one of the nests produced a nestling and one nest produced a fledgling; the outcomes of the other two nests were not determined.

The Common Black Hawk is currently being threatened by increased recreational usage of Fossil Creek and other riparian habitats and the invasion of the Salt Cedar, a nonnative exotic able to out-compete native nesting trees.

Yellow-Billed Cuckoo
The Yellow-Billed Cuckoo is a neotropical migrant that breeds throughout northern Mexico, the United States, and southern Canada. The Yellow-Billed Cuckoo was considered a common riparian species until the middle of the twentieth century, but its population has suffered catastrophic range reductions and habitat degradation in the time since. Consequentially, the bird was listed as a Candidate Species under the Endangered Species Act on July 25, 2001. It is considered as a species of Special Concern in Arizona and is on the Regional Forester’s Sensitive Species List.

Three of the four proposed Yellow-Billed Cuckoo surveys were completed during the 2005 breeding season, between June 25th and July 28th, 2005 (one survey was canceled due to fire closures). The surveys resulted in no detections of the species along the upper reaches of Fossil Creek. Because the riparian habitat along Fossil Creek appears to be suitable for the Yellow-billed Cuckoo, the reasons for its lack of presence in the area are unclear. However, habitat destruction in other areas has decreased the population of the bird, causing appropriate habitat to remain vacant.

Outcomes
The surveys increased the knowledge of the birds’ current populations and habitat requirements. This valuable data will help to implement more informed management decisions to aid in the species’ conservation. Through the Fossil Creek Watershed Monitoring Program, the Common Black Hawk and Yellow-billed Cuckoos were monitored again in 2006. This valuable data has provided information need to clarify Black Hawk population numbers, determine whether cuckoos breed in the area, and further define habitat use, potential threats, and management plans for each species.

For further information, see:
Johnson, M. J., J. Holmes and C. Calvo. 2005.  Common Black-Hawk and Yellow-billed Cuckoo distribution and abundance in the Upper Reaches of Fossil Creek, AZ, 2005. 22 pp.