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Federal Register / Vol. 86, No. 8 / Wednesday, January 13, 2021 / Rules and Regulations habitats have been incorporated into USACE river management programs as standard operating procedures SOPs or BMPs, including construction timing and work zone buffers to avoid disturbance of nesting colonies, dike modifications to protect and maintain habitat values, and dredge material disposal methods beneficial to maintaining nesting sand bars and islands e.g., USACE 2013, pp. 6972;
USACE 2016, p. 21. Other SOPs and BMPs incorporated into USACE
programs promote ecosystem productivity important to tern foraging, including articulated concrete mat design, use of hardpoints in lieu of revetment, and strategic placement of woody debris within channels e.g., USACE 2013, p. 71. These existing management strategies and programs USACE 2013, entire; 2016, entire;
2017a, entire are protective of waters and habitats managed by USACE that support about 80 percent of the Interior least terns range and have been a major factor in the recovery of the species. All USACE programs currently provide for adaptive management into the future, independent of the Federal listing status of the Interior least tern USACE 2013, p. 71; 2016, pp. 2, 24; 2018, pp. 413
417.
New information developed over the past three decades relative to the ecology of Interior least tern and its habitats indicate that recovery tasks to protect essential habitats across the species range through acquisition or easements are neither cost-effective nor necessary. Riverine habitat for Interior least terns is not static, and clearly experiences dramatic local or regional annual at times, daily variation in location, quantity, and quality.
Describing and quantifying habitat quality is difficult, given the wide variety of conditions the bird is known to exploit e.g., rivers, reservoirs, rooftops.
The Interior least tern adjusts to habitat variation and change over its range through metapopulation dynamics Hanski and Gilpin 1991, entire; Lott et al. 2013, p. 3620; Lott and Sheppard 2017, entire. A metapopulation consists of a network of populations with similar dynamics that are buffered against extinction by abandoning areas as habitats degrade, and dispersing and exploiting suitable habitats as they become available. Therefore, the importance of specific habitat segments to the species is likely to change with time. Within large metapopulations of mobile species, small subpopulations or colonies within subpopulations may occur in habitats where recruitment is inconsistent or may not exceed
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mortality i.e., population sinks, but which are maintained by immigration from colonies where recruitment exceeds mortality i.e., population sources. While exploitation of anthropogenic habitats by Interior least terns may indicate a lack of suitable habitat in an area, it may also indicate an overall population or subpopulation expansion. Sink colonies also play important roles in large metapopulations by providing opportunities for range expansion, and/
or redundancy from episodic stochastic impacts to preferred natural habitats.
While some colony sites may be periodic or consistent population sinks, there is no evidence that they are detracting from the Interior least terns rangewide survival e.g., Lott and Sheppard 2017a, p. 51, particularly in consideration of the substantial increase in the known number and size of tern colonies over the past two decades, and the expansion of the species distribution outside of its historical range i.e., Illinois, New Mexico, central Texas, Colorado; see Service 2013, pp.
3133.
Based upon this understanding of Interior least tern population dynamics and habitat use, the recovery task of protecting all areas identified in 1990 as essential across the species range through acquisition or easements is not necessary for the conservation of the species. This conclusion is supported by the increase in the species range and abundance over the past 30 years without protections achieved through such acquisition or easements. Although some Interior least tern nesting colonies occur on protected public lands such as National Wildlife Refuges, they represent only a small portion less than 2 percent of the rangewide population.
Additionally, as noted above, existing management agreements, strategies, and programs within jurisdictional waters are protective of the habitats that support about 80 percent of the Interior least tern population USACE 2013, entire; 2016, entire; 2017, entire.
While the majority 80 percent of Interior least tern nesting colonies are known from jurisdictional waters with a strong Federal connection with navigation systems or reservoirs, the remaining nesting colonies occur along rivers with a more limited Federal nexus, or on mining and industrial sites adjacent to or near rivers and reservoirs.
On about 10 percent of these, Federal, State, and/or private conservation partnerships have developed and implemented conservation agreements and management programs beneficial to Interior least tern as well as other at-risk or endangered species. These programs
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generally post or restrict access, control predators, and conduct monitoring during nesting season, as well as conduct vegetation control and public education as opportunities present.
In the Platte River drainage, the Tern and Plover Conservation Partnership was initiated in 1999, at the University of Nebraska, School of Natural Resources. This partnership consists of a group of State, industrial, Federal, and other cooperators having an interest in tern and plover conservation and management on and along the Platte, Loup, and Elkhorn Rivers, with emphasis on nesting areas associated with sand and gravel mines, lake shore housing developments, and dredging operations University of NebraskaLincoln 2019, entire. Long-term management of Interior least tern habitats in the Platte River drainage is also assured by an adaptive management plan developed and implemented by a partnership of State and industrial water users in Nebraska, Colorado, and Wyoming under the Platte River Recovery Implementation Program Platte River Recovery Implementation Program 2019, entire.
This program, initiated in 1997, also targets management needs of the endangered pallid sturgeon Scaphirhynchus albus and whooping crane Grus americana, and the threatened piping plover Charadrius melodus. Since both programs target other listed species with similar habitat requirements, and the Interior least tern is State-listed as endangered, these conservation programs and efforts are expected to continue regardless of a change in the Federal status of this species.
Interior least tern management in the Wabash River drainage began with the 1986 discovery of a single nesting pair on Gibson Generating Station property, Gibson County, Indiana Hayes and Pike 2011, entire; Mills 2018, pp. 25. This colonization led to site monitoring, predator control, and other protective measures, including vegetation control, water management, and habitat management and creation, resulting in increasing numbers of terns and expansion of nesting colonies to multiple sites on public and private properties in the vicinity Hayes and Pike 2011, entire. In 1999, management was formalized by development of a habitat conservation plan, which was renewed and revised in 2004, 2011, and 2018, by Duke Energy Corporation Hayes and Pike 2011, entire. The Indiana Nongame and Endangered Wildlife Program continues to coordinate conservation and monitoring efforts on industrial and river sites along
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