The Endangered Species Act of 1973 (ESA; 16 U.S.C. § 1531 et seq.) is one of the few dozens of US environmental laws passed in the 1970s, and serves as the enacting legislation to carry out the provisions outlined in The Convention on International Trade in Endangered Species of Wild Fauna and Flora ( CITES ).  Designed to protect critically imperiled species from extinction as a "consequence of economic growth and development untempered by adequate concern and conservation", the ESA was signed into law by President Richard Nixon on December 28, 1973. The U.S. Supreme Court found that "the plain intent of Congress in enacting" the ESA "was to halt and reverse the trend toward species extinction, whatever the cost."  The Act is administered by two federal agencies, the United States Fish and Wildlife Service (FWS) and the National Oceanic and Atmospheric Administration (NOAA).
- E = endangered (Sec.3.6, Sec.4.a  ) – any species which is in danger of extinction throughout all or a significant portion of its range other than a species of the Class Insecta determined by the Secretary to constitute a pest.
- T = threatened (Sec.3.20, Sec.4.a  ) – any species which is likely to become an endangered species within the foreseeable future throughout all or a significant portion of its range
- Other categories:
- C = candidate (Sec.4.b.3  ) – a species under consideration for official listing
- E(S/A), T(S/A) = endangered or threatened due to similarity of appearance (Sec.4.e  ) – a species not endangered or threatened, but so closely resembles in appearance a species which has been listed as endangered or threatened, that enforcement personnel would have substantial difficulty in attempting to differentiate between the listed and unlisted species.
- XE, XN = experimental essential or non-essential population (Sec.10.j  ) – any population (including eggs, propagules, or individuals) of an endangered species or a threatened species released outside the current range under authorization of the Secretary. Experimental, nonessential populations of endangered species are treated as threatened species on public land, for consultation purposes, and as species proposed for listing on private land.
The near-extinction of the bison and the disappearance of the passenger pigeon helped drive the call for wildlife conservation starting in the 1900s. Ornithologist George Bird Grinnell wrote articles on the subject in the magazine Forest and Stream , while Joel Asaph Allen , founder of the American Ornithologists' Union , hammered away in the popular press. The public was introduced to a new concept: extinction .
Market hunting for the millinery trade and for the table was one aspect of the problem. The early naturalists also killed birds and other wildlife for study, personal curio collections and museum pieces. While habitat losses continued as communities and farmland grew, the widespread use of pesticides and the introduction of non-native species also affected wildlife.
One species in particular received widespread attention—the whooping crane . The species' historical range extended from central Canada south to Mexico, and from Utah to the Atlantic coast . Unregulated hunting and habitat loss contributed to a steady decline in the whooping crane population until, by 1890, it had disappeared from its primary breeding range in the north central United States. It would be another eight years before the first national law regulating wildlife commerce was signed, and another two years before the first version of the endangered species act was passed. The whooping crane population by 1941 was estimated at about only 16 birds still in the wild. 
The Lacey Act of 1900 was the first federal law that regulated commercial animal markets. It prohibited interstate commerce of animals killed in violation of state game laws, and covered all fish and wildlife and their parts or products, as well as plants. Other legislation followed, including the Migratory Bird Conservation Act of 1929 , a 1937 treaty prohibiting the hunting of right and gray whales, and the Bald Eagle Protection Act of 1940. These later laws had a low cost to society–the species were relatively rare–and little opposition was raised.
Whereas the Lacey Act dealt with game animal management and market commerce species, a major shift in focus occurred by 1963 to habitat preservation instead of take regulations. A provision was added by Congress in the Land and Water Conservation Fund Act of 1965 that provided money for the "acquisition of land, waters...for the preservation of species of fish and wildlife that are threatened with extinction."
Act of 1966
The predecessor of the ESA was the Endangered Species Preservation Act of 1966 (P.L. 89-669 ). Passed by Congress, this act permitted the listing of native U.S. animal species as endangered and for limited protections upon those animals.
It authorized the Secretary of the Interior to list endangered domestic fish and wildlife and allowed the United States Fish and Wildlife Service to spend up to $15 million per year to buy habitats for listed species. It also directed federal land agencies to preserve habitat on their lands. The Act also consolidated and even expanded authority for the Secretary of the Interior to manage and administer the National Wildlife Refuge System . Other public agencies were encouraged, but not required, to protect species.  The act did not address the commerce in endangered species and parts. 
In March, 1967 the first list of endangered species was issued under the act. It included 14 mammals, 36 birds, 6 reptiles and amphibians and 22 fish. 
This first list is referred to as the "Class of '67" in The Endangered Species Act at Thirty , Volume 1, which concludes that habitat destruction, the biggest threat to those 78 species, is still the same threat to the currently listed species.  It included only vertebrates because the Department of Interior's definition of "fish and wildlife" was limited to vertebrates.  However, with time, researchers noticed that the animals on the endangered species list still were not getting enough protection, thus further threatening their extinction. The endangered species program was expanded by the Endangered Species Act of 1969.
Amendment of 1969
The Endangered Species Conservation Act (P. L. 91–135), passed in December, 1969, amended the original law to provide additional protection to species in danger of "worldwide extinction" by prohibiting their importation and subsequent sale in the United States. It expanded the Lacey Act's ban on interstate commerce to include mammals , reptiles , amphibians , mollusks and crustaceans . Reptiles were added mainly to reduce the rampant poaching of alligators and crocodiles .  This law was the first time that invertebrates were included for protection.
The amendment called for an international meeting to adopt a convention or treaty to conserve endangered species. That meeting was held in Washington, D.C., in February, 1973 and produced the comprehensive multilateral treaty known as CITES or Convention on International Trade of Endangered Species of Wild Fauna and Flora.
Endangered Species Act
President Richard Nixon declared current species conservation efforts to be inadequate and called on the 93rd United States Congress to pass comprehensive endangered species legislation.  Congress responded with a completely rewritten law, the Endangered Species Act of 1973, which was signed by Nixon on December 28, 1973 (). It was written by a team of lawyers and scientists, including Dr. Russell E. Train , the first appointed head of the Council on Environmental Quality (CEQ), an outgrowth of the National Environmental Policy Act (NEPA) of 1969.  Dr. Train was assisted by a core group of staffers, including Dr. Earl Baysinger at EPA, Dick Gutting, and Dr. Gerard A. "Jerry" Bertrand, a marine biologist by training, who had transferred from his post as the Scientific Adviser to the U.S Army Corps of Engineers, office of the Commandant of the Corps, to join the newly formed White House office.  The staff, under Dr. Train's leadership, incorporated dozens of new principles and ideas into the landmark legislation, crafting a document that completely changed the direction of environmental conservation in the United States. Dr. Bertrand is credited with writing the most challenged section of the Act, the "takings" clause – Section 2.
The stated purpose of the Endangered Species Act is to protect species and also "the ecosystems upon which they depend." California historian Kevin Starr was more emphatic when he said: "The Endangered Species Act of 1982 is the Magna Carta of the environmental movement." 
The ESA is administered by two federal agencies, the United States Fish and Wildlife Service (FWS) and the National Oceanic and Atmospheric Administration (NOAA) (which includes the National Marine Fisheries Service , or NMFS). NOAA handles marine species, and the FWS has responsibility over freshwater fish and all other species. Species that occur in both habitats (e.g. sea turtles and Atlantic sturgeon ) are jointly managed.
In March 2008, The Washington Post reported that documents showed that the Bush Administration , beginning in 2001, had erected "pervasive bureaucratic obstacles" that limited the number of species protected under the act:
- From 2000 to 2003, until a U.S. District Court overturned the decision, Fish and Wildlife Service officials said that if that agency identified a species as a candidate for the list, citizens could not file petitions for that species.
- Interior Department personnel were told they could use "info from files that refutes petitions but not anything that supports" petitions filed to protect species.
- Senior department officials revised a longstanding policy that rated the threat to various species based primarily on their populations within U.S. borders, giving more weight to populations in Canada and Mexico, countries with less extensive regulations than the U.S.
- Officials changed the way species were evaluated under the act by considering where the species currently lived, rather than where they used to exist.
- Senior officials repeatedly dismissed the views of scientific advisers who said that species should be protected.
In 2014, the House of Representatives passed the 21st Century Endangered Species Transparency Act, which would require the government to disclose the data it uses to determine species classification, but the President threatened a veto and the bill is unlikely to pass the Senate. 
The ESA's primary goal is to prevent the extinction of imperiled plant and animal life, and secondly, to recover and maintain those populations by removing or lessening threats to their survival.
Petition and listing
To be considered for listing, the species must meet one of five criteria (section 4(a)(1)):
1. There is the present or threatened destruction, modification, or curtailment of its habitat or range.
2. An over utilization for commercial, recreational, scientific, or educational purposes.
3. The species is declining due to disease or predation .
4. There is an inadequacy of existing regulatory mechanisms.
5. There are other natural or manmade factors affecting its continued existence.
Potential candidate species are then prioritized, with "emergency listing" given the highest priority. Species that face a "significant risk to their well being" are in this category. 
A species can be listed in two ways. The United States Fish and Wildlife Service (FWS) or NOAA Fisheries (also called the National Marine Fisheries Service ) can directly list a species through its candidate assessment program, or an individual or organizational petition may request that the FWS or NMFS list a species. A "species" under the act can be a true taxonomic species , a subspecies , or in the case of vertebrates, a " distinct population segment ." The procedures are the same for both types except with the person/organization petition, there is a 90-day screening period.
During the listing process, economic factors cannot be considered, but must be " based solely on the best scientific and commercial data available."  The 1982 amendment to the ESA added the word "solely" to prevent any consideration other than the biological status of the species. Congress rejected President Ronald Reagan 's Executive Order 12291 which required economic analysis of all government agency actions. The House committee's statement was "that economic considerations have no relevance to determinations regarding the status of species." 
The very opposite result happened with the 1978 amendment where Congress added the words "...taking into consideration the economic impact..." in the provision on critical habitat designation. The 1978 amendment linked the listing procedure with critical habitat designation and economic considerations, which almost completely halted new listings, with almost 2,000 species being withdrawn from consideration. 
After receiving a petition to list a species, the two federal agencies take the following steps, or rulemaking procedures, with each step being published in the Federal Register , the US government's official journal of proposed or adopted rules and regulations:
1. If a petition presents information that the species may be imperiled, a screening period of 90 days begins (interested persons and/or organization petitions only). If the petition does not present substantial information to support listing, it is denied.
2. If the information is substantial, a status review is started, which is a comprehensive assessment of a species' biological status and threats, with a result of : "warranted", "not warranted," or "warranted but precluded."
- A finding of not warranted, the listing process ends.
- Warranted finding means the agencies publish a 12-month finding (a proposed rule) within one year of the date of the petition, proposing to list the species as threatened or endangered. Comments are solicited from the public, and one or more public hearings may be held. Three expert opinions from appropriate and independent specialists may be included, but this is voluntary.
- A "warranted but precluded" finding is automatically recycled back through the 12-month process indefinitely until a result of either "not warranted" or "warranted" is determined. The agencies monitor the status of any "warranted but precluded" species. 
Essentially the "warranted but precluded" finding is a deferral added by the 1982 amendment to the ESA. It means other, higher-priority actions will take precedence.  For example, an emergency listing of a rare plant growing in a wetland that is scheduled to be filled in for housing construction would be a "higher-priority".
3. Within another year, a final determination (a final rule) must be made on whether to list the species. The final rule time limit may be extended for 6 months and listings may be grouped together according to similar geography, threats, habitat or taxonomy.
The annual rate of listing (i.e., classifying species as "threatened" or "endangered") increased steadily from the Ford administration (47 listings, 15 per year) through Carter (126 listings, 32 per year), Reagan (255 listings, 32 per year), George H. W. Bush (231 listings, 58 per year), and Clinton (521 listings, 65 per year) before decline to its lowest rate under George W. Bush (60 listings, 8 per year as of 5/24/08).
The rate of listing is strongly correlated with citizen involvement and mandatory timelines: as agency discretion decreases and citizen involvement increases (i.e. filing of petitions and lawsuits) the rate of listing increases. Citizen involvement has been shown to identify species not moving through the process efficiently,  and identify more imperiled species.  The longer species are listed, the more likely they are to be classified as recovering by the FWS. 
Public notice, comments and judicial review
Public notice is given through legal notices in newspapers, and communicated to state and county agencies within the species' area. Foreign nations may also receive notice of a listing. A public hearing is mandatory if any person has requested one within 45 days of the published notice. "The purpose of the notice and comment requirement is to provide for meaningful public participation in the rulemaking process." summarized the Ninth Circuit court in the case of Idaho Farm Bureau Federation v. Babbitt .
Species survival and recovery
The provision of the law in Section 4 that establishes critical habitat is a regulatory link between habitat protection and recovery goals, requiring the identification and protection of all lands, water and air necessary to recover endangered species. To determine what exactly is critical habitat, the needs of open space for individual and population growth, food, water, light or other nutritional requirements, breeding sites, seed germination and dispersal needs, and lack of disturbances are considered.
As habitat loss is the primary threat to most imperiled species, the Endangered Species Act of 1973 allowed the Fish and Wildlife Service (FWS) and National Marine Fisheries Service (NMFS) to designate specific areas as protected "critical habitat" zones. In 1978, Congress amended the law to make critical habitat designation a mandatory requirement for all threatened and endangered species.
The amendment also added economics into the process of determining habitat: "...shall designate critical habitat... on the basis of the best scientific data available and after taking into consideration the economic impact, and any other impact, of specifying... area as critical habitat." The congressional report on the 1978 amendment described the conflict between the new Section 4 additions and the rest of the law:
"... the critical habitat provision is a startling section which is wholly inconsistent with the rest of the legislation. It constitutes a loophole which could readily be abused by any Secretary ... who is vulnerable to political pressure or who is not sympathetic to the basic purposes of the Endangered Species Act."-- House of Representatives Report 95-1625, at 69 (1978)
The amendment of 1978 added economic considerations and the 1982 amendment prevented economic considerations.
Several studies on the effect of critical habitat designation on species' recovery rates have been done between 1997 and 2003. Although it has been criticized,  the Taylor study in 2003 found that, "species with critical habitat were... twice as likely to be improving...."
Critical habitats are required to contain "all areas essential to the conservation" of the imperiled species, and may be on private or public lands. The Fish and Wildlife Service has a policy limiting designation to lands and waters within the U.S. and both federal agencies may exclude essential areas if they determine that economic or other costs exceed the benefit. The ESA is mute about how such costs and benefits are to be determined.
All federal agencies are prohibited from authorizing, funding or carrying out actions that "destroy or adversely modify" critical habitats (Section 7(a) (2)). While the regulatory aspect of critical habitat does not apply directly to private and other non-federal landowners, large-scale development, logging and mining projects on private and state land typically require a federal permit and thus become subject to critical habitat regulations. Outside or in parallel with regulatory processes, critical habitats also focus and encourage voluntary actions such as land purchases, grant making, restoration, and establishment of reserves .
The ESA requires that critical habitat be designated at the time of or within one year of a species being placed on the endangered list. In practice, most designations occur several years after listing. Between 1978 and 1986 the FWS regularly designated critical habitat. In 1986 the Reagan Administration issued a regulation limiting the protective status of critical habitat. As a result, few critical habitats were designated between 1986 and the late 1990s. In the late 1990s and early 2000s, a series of court orders invalidated the Reagan regulations and forced the FWS and NMFS to designate several hundred critical habitats, especially in Hawaii, California and other western states. Midwest and Eastern states received less critical habitat, primarily on rivers and coastlines. As of December, 2006, the Reagan regulation has not yet been replaced though its use has been suspended. Nonetheless, the agencies have generally changed course and since about 2005 have tried to designate critical habitat at or near the time of listing.
Most provisions of the ESA revolve around preventing extinction. Critical habitat is one of the few that focus on recovery. Species with critical habitat are twice as likely to be recovering as species without critical habitat. 
Plans, permits, and agreements
The combined result of the amendments to the Endangered Species Act have created a law vastly different from the ESA of 1973. It is now a flexible, permitting statute. For example, the law now permits "incidental takes" (accidental killing or harming a listed species). Congress added the requirements for "incidental take statement", and authorized a "incidental take permit" in conjunction with "habitat conservation plans".
More changes were made in the 1990s in an attempt by Secretary of the Interior Bruce Babbitt to shield the ESA from a Congress hostile to the law. He instituted incentive-based strategies such as candidate conservation agreements and "safe harbor" agreements that would balance the goals of economic development and conservation.
Fish and Wildlife Service (FWS) and National Marine Fisheries Service (NMFS) are required to create an Endangered Species Recovery Plan outlining the goals, tasks required, likely costs, and estimated timeline to recover endangered species (i.e., increase their numbers and improve their management to the point where they can be removed from the endangered list). The ESA does not specify when a recovery plan must be completed. The FWS has a policy specifying completion within three years of the species being listed, but the average time to completion is approximately six years. The annual rate of recovery plan completion increased steadily from the Ford administration (4) through Carter (9), Reagan (30), Bush I (44), and Clinton (72), but declined under Bush II (16 per year as of 9/1/06).
The goal of the law is to make itself unnecessary, and recovery plans are a means toward that goal. Recovery plans became more specific after 1988 when Congress added provisions to Section 4(f) of the law that spelled out the minimum contents of a recovery plan. Three types of information must be included:
- A description of "site-specific" management actions to make the plan as explicit as possible.
- The "objective, measurable criteria" to serve as a baseline for judging when and how well a species is recovering.
- An estimate of money and resources needed to achieve the goal of recovery and delisting.
The amendment also added public participation to the process. There is a ranking order, similar to the listing procedures, for recovery plans, with the highest priority being for species most likely to benefit from recovery plans, especially when the threat is from construction, or other developmental or economic activity. Recovery plans cover domestic and migratory species.
Exemptions can and do occur. The ESA requires federal agencies to consult with the US Fish and Wildlife Service (FWS) or the National Marine Fisheries Service (NMFS) if any project occurs in the habitat of a listed species. An example of such a project might be a timber harvest proposed by the US Forest Service . If the timber harvest could impact a listed species, a biological assessment is prepared by the Forest Service and reviewed by the FWS or NMFS or both.
The question to be answered is whether a listed species will be harmed by the action and, if so, how the harm can be minimized. If harm cannot be avoided, the project agency can seek an exemption from the Endangered Species Committee, an ad hoc panel composed of members from the executive branch and at least one appointee from the state where the project is to occur. Five of the seven committee members must vote for the exemption to allow taking (to harass, harm, pursue, hunt, shoot, wound, kill, trap, capture, or collect, or significant habitat modification,  or to attempt to engage in any such conduct) of listed species.
Long before the exemption is considered by the Endangered Species Committee, the Forest Service, and either the FWS or the NMFS will have consulted on the biological implications of the timber harvest. The consultation can be informal, to determine if harm may occur; and then formal if the harm is believed to be likely. The questions to be answered in these consultations are whether the species will be harmed, whether the habitat will be harmed and if the action will aid or hinder the recovery of the listed species.
If harm is likely to occur, the consultation evaluates whether "reasonable and prudent alternatives" exist to minimize harm. If an alternative does not exist, the FWS or NMFS will issue an opinion that the action constitutes "jeopardy" to the listed species either directly or indirectly. The project cannot then occur unless exempted by the Endangered Species Committee.
The Committee must make a decision on the exemption within 30 days, when its findings are published in the Federal Register . The findings can be challenged in federal court. In 1992, one such challenge was the case of Portland Audubon Society v. Endangered Species Committee heard in the Ninth Circuit Court of Appeals. 
The court found that three members had been in illegal ex parte contact with the then-President George H.W. Bush, a violation of the Administrative Procedures Act . The committee's exemption was for the Bureau of Land Management 's timber sale and "incidental takes" of the endangered northern spotted owl in Oregon. 
There have been six instances as of 2009 in which the exemption process was initiated. Of these six, one was granted, one was partially granted, one was denied and three were withdrawn.  Donald Baur, in The Endangered Species Act: law, policy, and perspectives , concluded," ... the exemption provision is basically a nonfactor in the administration of the ESA. A major reason, of course, is that so few consultations result in jeopardy opinions, and those that do almost always result in the identification of reasonable and prudent alternatives to avoid jeopardy."
Habitat Conservation Plans
More than half of habitat for listed species is on non-federal property, owned by citizens, states, local governments, tribal governments and private organizations. Before the law was amended in 1982, a listed species could be taken only for scientific or research purposes. The amendment created a permit process to circumvent the take prohibition called a Habitat Conservation Plan or HCP to give incentives to non-federal land managers and private landowners to help protect listed and unlisted species, while allowing economic development that may harm ("take") the species.
The US Fish and Wildlife Service defines the process as: "The purpose of the habitat conservation planning process associated with the permit is to ensure there is adequate minimizing and mitigating of the effects of the authorized incidental take. The purpose of the incidental take permit is to authorize the incidental take of a listed species, not to authorize the activities that result in take." 
The person or organization submits a HCP and if approved by the agency (FWS or NMFS), will be issued an Incidental Take Permit (ITP) which allows a certain number of "takes" of the listed species. The permit may be revoked at any time and can allow incidental takes for varying amounts of time. For instance, the San Bruno Habitat Conservation Plan/ Incidental Take Permit is good for 30 years and the Wal-Mart store (in Florida) permit expires after one year. Because the permit is issued by a federal agency to a private party, it is a federal action-which means other federal laws can apply, such as the National Environmental Policy Act or NEPA. A notice of the permit application action is published in the Federal Register and a public comment period of 30 to 90 days begins.
The US Congress was urged to create the exemption by proponents of a conservation plan on San Bruno Mountain , California that was drafted in the early 1980s and is the first HCP in the nation. In the conference report on the 1982 amendments, Congress specified that it intended the San Bruno plan to act "as a model" for future conservation plans developed under the incidental take exemption provision and that "the adequacy of similar conservation plans should be measured against the San Bruno plan". Congress further noted that the San Bruno plan was based on "an independent exhaustive biological study" and protected at least 87% of the habitat of the listed butterflies that led to the development of the HCP. 
Growing scientific recognition of the role of private lands for endangered species recovery and the landmark 1981 court decision in Palila v. Hawaii Department of Land and Natural Resources both contributed to making Habitat Conservation Plans/ Incidental Take Permits "a major force for wildlife conservation and a major headache to the development community", wrote Robert D.Thornton in the 1991 Environmental Law article, Searching for Consensus and Predictability: Habitat Conservation Planning under the Endangered Species Act of 1973 . 
"No Surprises" rule
The "No Surprises" rule is meant to protect the landowner if "unforeseen circumstances" occur which make the landowner's efforts to prevent or mitigate harm to the species fall short. The "No Surprises" policy may be the most controversial of the recent reforms of the law, because once an Incidental Take Permit is granted, the Fish and Wildlife Service (FWS) loses much ability to further protect a species if the mitigation measures by the landowner prove insufficient. The landowner or permittee would not be required to set aside additional land or pay more in conservation money. The federal government would have to pay for additional protection measures.
"Safe Harbor" agreements
The "Safe Harbor" agreement is a voluntary agreement between the private landowner and FWS. The landowner agrees to alter the property to benefit or even attract a listed or proposed species in exchange for assurances that the FWS will permit future "takes" above a pre-determined level. The policy relies on the "enhancement of survival" provision of Section §1539(a)(1)(A). A landowner can have either a "Safe Harbor" agreement or an Incidental Take Permit, or both. The policy was developed by the Clinton Administration in 1999.
Candidate Conservation Agreements
The Candidate Conservation Agreement is closely related to the "Safe Harbor" agreement, the main difference is that the Candidate Conservation Agreements With Assurances(CCA) are meant to protect unlisted species by providing incentives to private landowners and land managing agencies to restore, enhance or maintain habitat of unlisted species which are declining and have the potential to become threatened or endangered if critical habitat is not protected. The FWS will then assure that if, in the future the unlisted species becomes listed, the landowner will not be required to do more than already agreed upon in the CCA.
The Experimental Population Provision encourages introductions of species into formerly occupied or new habitat without the full range of legal restrictions for endangered species. The provision was added to the act in 1982 to encourage landowner support for species survival and recovery. Experimental populations could be used for the assisted migration of endangered species. 
To delist species, several factors are considered: the threats are eliminated or controlled, population size and growth, and the stability of habitat quality and quantity. Also, over a dozen species have been delisted due to inaccurate data putting them on the list in the first place.
There is also "downlisting" of a species where some of the threats have been controlled and the population has met recovery objectives, then the species can be reclassified to "threatened" from "endangered" 
Two examples of animal species recently delisted are: the Virginia northern flying squirrel (subspecies) on August, 2008, which had been listed since 1985, and the gray wolf (Northern Rocky Mountain DPS). On April 15, 2011, President Obama signed the Department of Defense and Full-Year Appropriations Act of 2011.  A section of that Appropriations Act directed the Secretary of the Interior to reissue within 60 days of enactment the final rule published on April 2, 2009, that identified the Northern Rocky Mountain population of gray wolf ( Canis lupus ) as a distinct population segment (DPS) and to revise the List of Endangered and Threatened Wildlife by removing most of the gray wolves in the DPS.
The US Fish and Wildlife Service's delisting report lists four plants that have recovered: 
- Eggert's sunflower ( Helianthus eggertii )
- Robbins' cinquefoil ( Potentilla robbinsiana ), an alpine wildflower found only in the White Mountains of New Hampshire
- Maguire daisy ( Erigeron maguirei )
- Tennessee purple coneflower ( Echinacea tennesseensis )
As of September 2012, fifty-six species have been delisted; twenty-eight due to recovery, ten due to extinction (seven of which are believed to have been extinct prior to being listed), ten due to changes in taxonomic classification practices, six due to discovery of new populations, one due to an error in the listing rule, and one due to an amendment to the Endangered Species Act specifically requiring the species delisting.  Twenty-five others have been down listed from "endangered" to "threatened" status.
Some have argued that the recovery of DDT-threatened species such as the bald eagle , brown pelican and peregrine falcon should be attributed to the 1972 ban on DDT by the EPA . rather than the Endangered Species Act, however, the listing of these species as endangered was a substantial cause of Congress instituting the ban and many non-DDT oriented actions were taken on their behalf under the Endangered Species Act (i.e. captive breeding, habitat protection, and protection from disturbance).
As of October 28, 2012, there are 2,052 total (foreign and domestic)  species on the threatened and endangered lists. However, many species have become extinct while on the candidate list or otherwise under consideration for listing.
Species which increased in population size since being placed on the endangered list include:
- Bald eagle (increased from 417 to 11,040 pairs between 1963 and 2007); removed from list 2007
- Whooping crane (increased from 54 to 436 birds between 1967 and 2003)
- Kirtland's warbler (increased from 210 to 1,415 pairs between 1971 and 2005)
- Peregrine falcon (increased from 324 to 1,700 pairs between 1975 and 2000); removed from list 1999
- Gray wolf (populations increased dramatically in the Northern Rockies and Western Great Lakes States)
- Mexican wolf (increased to minimum population of 109 wolves in 2014 in southwest New Mexico and southeast Arizona)
- Red wolf (increased from 17 in 1980 to 257 in 2003)
- Gray whale (increased from 13,095 to 26,635 whales between 1968 and 1998); removed from list (Debated because whaling was banned before the ESA was set in place and that the ESA had nothing to do with the natural population increase since the cease of massive whaling [excluding Native American tribal whaling])
- Grizzly bear (increased from about 271 to over 580 bears in the Yellowstone area between 1975 and 2005); removed from list March 22, 2007
- California’s southern sea otter (increased from 1,789 in 1976 to 2,735 in 2005)
- San Clemente Indian paintbrush (increased from 500 plants in 1979 to more than 3,500 in 1997)
- Florida's Key deer (increased from 200 in 1971 to 750 in 2001)
- Big Bend gambusia (increased from a couple dozen to a population of over 50,000)
- Hawaiian goose (increased from 400 birds in 1980 to 1,275 in 2003)
- Virginia big-eared bat (increased from 3,500 in 1979 to 18,442 in 2004)
- Black-footed ferret (increased from 18 in 1986 to 600 in 2006)
Opponents of the Endangered Species Act argue that with over 2,000 endangered species listed,   and only 28 delisted due to recovery, the success rate of 1% over nearly three decades proves that there needs to be serious reform in their methods to actually help the endangered animals and plants. Others argue that the ESA may encourage preemptive habitat destruction by landowners who fear losing the use of their land because of the presence of an endangered species; known colloquially as " Shoot, Shovel and Shut-Up ." One example of such perverse incentives is the case of a forest owner who, in response to ESA listing of the red-cockaded woodpecker , increased harvesting and shortened the age at which he harvests his trees to ensure that they do not become old enough to become suitable habitat.  While no studies have shown that the Act's negative effects, in total, exceed the positive effects, many economists believe that finding a way to reduce such perverse incentives would lead to more effective protection of endangered species. 
According to research published in 1999 by Alan Green and the Center for Public Integrity (CPI), loopholes in the ESA are commonly exploited in the exotic pet trade . Although the legislation prohibits interstate and foreign transactions for list species, no provisions are made for in-state commerce, allowing these animals to be sold to roadside zoos and private collectors. Additionally, the ESA allows listed species to be shipped across state lines as long as they are not sold. According to Green and the CPI, this allows dealers to "donate" listed species through supposed "breeding loans" to anyone, and in return they can legally receive a reciprocal monetary "donation" from the receiving party. Furthermore, an interview with an endangered species specialist at the US Fish and Wildlife Service revealed that the agency does not have sufficient staff to perform undercover investigations, which would catch these false "donations" and other mislabeled transactions.
Green and the CPI further noted another exploit of the ESA in their discussion of the critically endangered cotton-top tamarin ( Saguinus oedipus ). Not only had they found documentation that 151 of these primates had inadvertently made their way from the Harvard -affiliated New England Regional Primate Research Center into the exotic pet trade through the aforementioned loophole, but in October 1976, over 800 cotton-top tamarins were imported into the United States in order to beat the official listing of the species under the ESA.
State endangered species lists
Section 6 of the Endangered Species Act  provided funding for development of programs for management of threatened and endangered species by state wildlife agencies.  Subsequently, lists of endangered and threatened species within their boundaries have been prepared by each state. These state lists often include species which are considered endangered or threatened within a specific state but not within all states, and which therefore are not included on the national list of endangered and threatened species. Examples include Florida,  Minnesota,  Maine, 
There are different degrees of violation with the law. The most punishable offenses are trafficking, and any act of knowingly "taking" (which includes harming, wounding, or killing) an endangered species.
The penalties for these violations can be a maximum fine of up to $50,000 or imprisonment for one year, or both, and civil penalties of up to $25,000 per violation may be assessed. Lists of violations and exact fines are available through the National Oceanic and Atmospheric Administration web-site. 
One provision of this law is that no penalty may be imposed if, by a preponderance of the evidence that the act was in self-defense. The law also eliminates criminal penalties for accidentally killing listed species during farming and ranching activities. 
In addition to fines or imprisonment, a license, permit, or other agreement issued by a federal agency that authorized an individual to import or export fish, wildlife, or plants may be revoked, suspended or modified. Any federal hunting or fishing permits that were issued to a person who violates the ESA can be canceled or suspended for up to a year.
Use of money received through violations of the ESA
A reward will be paid to any person who furnishes information which leads to an arrest, conviction, or revocation of a license, so long as they are not a local, state, or federal employee in the performance of official duties. The Secretary may also provide reasonable and necessary costs incurred for the care of fish, wildlife, and forest service or plant pending the violation caused by the criminal. If the balance ever exceeds $500,000 the Secretary of the Treasury is required to deposit an amount equal to the excess into the cooperative endangered species conservation fund.