1. Genus and species names can be found in appendix 3.
2. Frohoff 1996.
3. Kathleen Dudzinski, personal data and observations, 1997–2007.
4. See Perrin et al. 2002 for more details.
5. Baleen is unique to mysticetes. It is composed of keratin (the same substance that makes hair, nails, and horns in many other animals), but in these whales, it occurs in plates of bristles in the mouth where teeth might be found otherwise. These bristles form a filter through which food (such as krill or small fish) can be retained in the mouth while water is expelled through the baleen.
6. Reynolds and Rommel 1999; Perrin, Würsig, and Thewissen 2002.
7. Reynolds, Wells, and Eide 2000.
8. Reiss and Marino 2001; Herman, Morrel-Samuels, and Pack 1990; Herman et al. 1999; Herman et al. 2001.
9. Reiss and Marino 2001.
10. Rendell and Whitehead 2001:309.
11. Pryor 1973.
12. Untapped ecological niche: Barnes 1984.
13. Berta and Sumich 2004.
14. Thewissen and Williams 2002; Thewissen et al. 2006.
15. Thewissen et al. 2006.
16. Berta and Sumich 2004.
17. Thewissen et al. 2006.
18. Nikaido, Rooney, and Okada 1999.
19. Barklow 1997, 2004.
20. Barklow 1994, 1995, 2004.
21. Barklow 2004.
22. Barklow 1997, 2004.
23. Hof et al. 2000.
24. Langbauer et al. 1989.
25. Marino 2004.
26. Marino 2004; Hof, Chanis, and Marino 2005.
27. Marino 2002, 2004.
28. Social ecology: Connor et al. 1998; communication: Jerison 1973.
29. Mirror self-recognition: Reiss and Marino 2001; Marten and Psarakos 1995; abstract concepts: Herman, Richards, and Wolz 1984; Herman et al. 2001; learning: Janik and Slater 2000; culture: Rendell and Whitehead 2001.
30. Watkins and Wartzok 1985.
31. Mass and Ya 1995; van der Pol, Worst, and Andel 1995; Mass and Supin 2002.
32. Tarpley and Ridgway 1994.
33. Herman et al. 1975; Norris et al. 1994.
34. Herman et al. 1975.
35. Mass and Supin 2002.
36. Watkins and Wartzok 1985.
37. Van der Pol, Worst, and Andel 1995.
38. Pryor 1990a; Herzing 1990.
39. Würsig, Kieckhefer, and Jefferson 1990.
40. Perrin 1970; Herzing 1991a.
41. Leatherwood and Reeves 1983.
42. Würsig and Würsig 1980.
43. Norris et al. 1994.
44. Geraci 1986.
45. Pryor 1990a.
46. Worthy and Edwards 1990.
47. Perrin, Würsig, and Thewissen 2002.
48. Ridgway, Scronce, and Kanwisher 1969.
49. Polasek and Davis 2001.
50. Williams et al. 1992.
51. Reynolds and Rommel 1999; Thewissen, Williams, and Hussain 2000.
52. Caldwell and Caldwell 1977.
53. Clark and Mangel 1986.
54. Gubbins 2002.
55. Sargeant et al. 2005.
56. Personal communication between Alejandro Acevedo and Kathleen Dudzinski in mid-1990s and in 2006 to invigorate Kathleen’s aging memory.
57. Dudzinski 1998; Dudzinski et al. (submitted).
58. Ballance 1990.
59. Bottlenose dolphin groups: Leatherwood and Reeves 1983; companions change: Wells 1991.
60. Wells, Scott, and Irvine 1987; Connor 1990a, 1990b.
61. Ford et al. 1999.
62. Shane 1990.
63. Aggressive behavior: Norris 1969; Pryor and Shallenberger 1991 with sexual behavior: Taylor and Saayman 1972; Pryor and Shallenberger 1991; Saayman and Taylor 1979.
64. Östman 1994.
65. Simard and Gowans 2004.
66. Bel’kovich 1991.
67. Bel’kovich 1991.
68. Dudzinski, unpublished data 1997–2006; Paulos, Dudzinski, and Kuczaj 2008.
69. Bel’kovich 1991.
70. Fagan 1981; Bekoff 1984.
71. Play variable: Bekoff 1972; environmental contexts: Bekoff 1995.
72. McBride and Hebb 1948; Morgan 1968; Taylor and Saayman 1972; Norris and Dohl 1980; Bel’kovich 1991; Hankins 1993.
73. Bel’kovich 1991.
74. Dudzinski, Douaze, and Thomas 2002.
75. Wells, Irvine, and Scott 1980; Johnson and Norris 1986.
76. Bottlenose dolphins: Shane 1977; Würsig and Würsig 1979; Wells, Scott, and Irvine 1987; Connor 1990a, 1990b; harbor porpoise: Gaskin 1982; short-finned pilot whales: Heimlich-Boran 1988.
77. Atlantic spotted dolphins: Herzing 1993; Dudzinski 1996; Hawaiian spinner dolphins: Norris et al. 1994; Östman 1994; dusky dolphins: Würsig and Würsig 1980; Cipriano 1992; humpback dolphins: Saayman and Taylor 1979; Karczmarski, Thornton, and Cockcroft 1997; killer whales: e.g., Ford et al. 1999.
78. Evans 1987; Grier and Burk 1992; Frohoff 2007.
1. This action is what animal behaviorists might consider an example of “displacement behavior.”
2. For in-depth information about communication and its evolution, see Hauser 1996 and Bradbury and Vehrencamp 1998.
3. Consortship pops: Connor and Smolker 1996; maternal thunks: McCowan and Reiss 1995a.
4. Von Frisch 1967.
5. Poole 1996:143.
6. Dudzinski 1998; Herzing 1991b.
7. Dudzinski 1998.
8. Herman and Tavolga 1980; Caldwell, Caldwell, and Tyack 1990.
9. Unique to dolphins: Podos, Da Silva, and Rossi-Santos 2002; across species: Steiner 1981; Wang, Würsig, and Evans 1995a; Rendell et al. 1999; across geographic locations: BazúaDurán and Au 2004; across social groups: Janik 2000; across populations: Azevedo and Van Sluys 2005; Wang, Würsig, and Evans 1995b; Morisaka et al. 2005; different gender and age: Sayigh et al. 1995.
10. Caldwell and Caldwell 1977; Herman and Tavolga 1980.
11. Au 1993.
12. Reidenberg and Laitman 1988.
13. Cranford, Amundin, and Norris 1992.
14. Dawson 1991.
15. Ketten 1992; Cranford, Amundin, and Norris 1992.
16. Hemila and Nummelaa 1999.
17. Hemila and Nummelaa 1999; Vater and Kössl 2004.
18. Hemila and Nummelaa 1999.
19. Thewissen 2002.
20. Au 1993.
21. Spinka, Newberry, and Bekoff 2001.
22. Group hunting: Würsig and Würsig 1980; crater feeding: Rossbach and Herzing 1997; mud banks: Petricig 1993; Gubbins 2002; beaches: Sargeant et al. 2005; stun fish: Wells, Scott, and Irvine 1987; Connor et al. 2000; corral fish: Fertl and Würsig 1995.
23. Guinet and Bouvier 1995; Baird and Whitehead 2000.
24. Petricig 1993, 1995; Gubbins 2002, see review by Silber and Fertl 1995.
25. Sargeant et al. 2005.
26. Fedorowicz, Beard, and Connor 2003.
27. Gazda et al. 2005.
28. Packer 1994.
29. Moehlman 1989.
30. For example, Connor and Smolker 1985; Wells, Scott, and Irvine 1987; Wells 1991; Fertl 1994; Rossbach and Herzing 1997.
31. Mann and Smuts 1999.
32. Hendry 2003.
33. Kuczaj and Highfill 2005; Kuczaj and Yeater 2006.
34. Mann et al. 2000.
35. Yurk et al. 2002.
36. Ford 1989, 1991.
37. Ford 1989, 1991.
38. Poole 1996.
39. Nousek et al. 2006.
40. Norway: Similiä 1997.
41. Bain 1986; Baird 2000.
42. Moss 1982.
43. Poole 1996.
44. Caldwell, Caldwell, and Tyack 1990; Lammers and Au 2003.
45. Caldwell and Caldwell 1965.
46. Caldwell and Caldwell 1968.
47. Dreher 1961; Dreher and Evans 1964.
48. Caldwell, Caldwell, and Tyack 1990.
49. McCowan and Reiss 1995b, 1995c.
50. Smolker, Mann, and Smuts 1993.
51. Sayigh et al. 1990.
52. Janik and Slater 1998.
53. Trivers 1971; Connor and Norris 1982.
54. Tyack and Sayigh 1997.
55. Janik and Slater 1998; Tyack and Sayigh 1997.
56. Trainer’s whistle: Kathleen Dudzinski and trainers at Roatan Institute for Marine Sciences, Anthony’s Key Resort, Roatan, Honduras, personal communication, 2003; truck noises: Poole 1996.
57. Moss 1982.
58. Wells, Scott, and Irvine 1987; Connor, Heithaus, and Barre 1999.
59. Seyfarth and Cheney 1999; Janik and Slater 1998.
60. Azevedo and van Sluys 2005.
1. Goodall 1986.
2. Payne 1998.
3. Reynolds and Rommel 1999.
4. Kathleen Dudzinski’s observations of spotted dolphins in The Bahamas, 1992–2002.
5. Moss 1982.
6. Dudzinski 1996.
7. Frohoff 1993, 1996.
8. Würsig and Würsig 1980.
9. Norris et al. 1994.
10. Frohoff 2004.
11. S-shaped posture: Norris et al. 1994.
12. Würsig and Würsig 1980; Fertl and Würsig 1995; Dudzinski 1996.
13. Connor and Smolker 1996.
14. Caldwell, Caldwell, and Tyack 1990; McCowan and Reiss 1995.
15. Norris and Dohl 1980.
16. Griffin 1986.
17. Dudzinski 1996; Herzing 2000.
18. Xitco and Roitblat 1996.
19. Gregg, Dudzinski, and Smith 2007.
20. Dawson 1991.
21. Norris et al. 1994.
22. Frohoff, Packard, and Benson 1996.
23. Dudzinski, Clark, and Würsig 1995.
24. Dudzinski and Newborough 1997.
25. Schotten et al. 2005.
26. Morton 1977.
27. Dudzinski 1998.
28. Waples and Gales 2002.
29. Dudzinski 1996, 1998.
30. Walther 1984.
31. Krebs and Dawkins 1984.
32. Walther 1984; Krebs and Dawkins 1984; W. J. Smith 1991.
33. Fagan 1981.
34. Norris et al. 1994; Goodall 1971; Patterson 1978; Fossey 1983.
35. Herzing 1991a.
36. Bernd Würsig, personal communication, 1998. Rochelle Constantine, personal communication, 1999.
37. Atlantic spotted dolphins: Herzing 1991b; Dudzinski 1996; bottlenose dolphins: e.g., Dudzinski, Frohoff, and Crane 1995; beluga whales: Frohoff, Vail, and Bossley 2005, 2006; captive dolphins: Defran and Pryor 1980; Herman 1980; Stan Kuczaj, personal communication, 2002.
38. Walther 1984; Krebs and Dawkins 1984; Pryor 1986; W. J. Smith 1991.
39. Pryor 1986:256.
40. Communication through play: Fagan 1981; play in development of communication: Bekoff 1972; Spinka, Newberry, and Bekoff 2001.
41. Beach 1945; Fagan 1981.
42. Norris and Dohl 1980; Herzing 1993; Frohoff 1996.
43. Sweeney 1990.
1. Biologist Raymond Coppinger in Dogs That Changed the World, “Part 1: The Rise of the Dog,” first broadcast January 13, 2008, on PBS; directed and produced by Corinna Faith.
2. Skinner 1938.
3. Darwin 1965.
4. Lusseau and Newman 2004.
5. Herman 2006.
6. Connor and Mann 2006.
7. Fraser et al. 2006.
8. Marino 2002.
9. Marino, McShea, and Uhen 2004.
10. Manger 2006.
11. Marino 2004.
12. Marino 2004.
13. Ridgway 2000.
14. Marino et al. 2000.
15. Marino 2004.
16. Marino 2004.
17. Space needed for processing auditory information: Simmonds 2006; rejection of this idea: Pabst, Rommel, and McLellan 1999.
18. Manger 2006.
19. Lilly 1961, 1978.
20. Lilly 1967.
21. Lilly 1973.
22. Norris 1969; Pryor and Norris 1991.
23. Miller 2003.
24. Schusterman and Gisiner 1988.
25. Pinker 1995.
26. Lilly 1961.
27. Batteau and Markey 1966.
28. Gardner and Gardner 1969; Premack 1971.
29. Bonobos: Savage-Rumbaugh et al. 1985; gorillas: Patterson 1978; parrots: Pepperberg and Brezinsky 1991.
30. Herman, Richards, and Wolz 1984.
31. Herman 2006.
32. Herman, Richards, and Wolz 1984.
33. Controversy: Schusterman and Gisiner 1988.
34. Herman 2006.
35. Visual and echolocation systems: Harley, Roitblat, and Nachtigall 1996; episodic memory: Dere et al. 2006; event memory: Mercado et al. 1999; perceive and classify objects: Mercado et al. 1999.
36. Herman, Morrel-Samuels, and Pack 1990.
37. Pryor 1973, 1986; Herman 2006.
38. Connor, Smolker, and Bejder 2006.
39. Herman 2006.
40. Fellner, Bauer, and Harley 2006.
41. Herman et al. 1999.
42. Tschudin et al. 2001.
43. Chimpanzees: Leavens 2004; dogs: Miklósi et al. 1998.
44. Xitco, Gory, and Kuczaj 2001.
45. Xitco, Gory, and Kuczaj 2004.
46. Dudzinski et al. 2003.
47. Pack and Herman 2007.
48. Xitco and Roitblat 1996.
49. Pack and Herman 2006.
50. Consciousness explained: Dennett 1991; present only in humans: Wynne 2004; found in nonhuman animals: Allen 1998.
51. Herman et al. 2001.
52. Xitco 1988.
53. Kuczaj and Yeater 2006.
54. Reiss and Marino 2001.
55. Gallup 1970.
56. Elephants: Plotnik, de Waal, and Reiss 2006; great apes: Povinelli et al. 1997.
57. Dolphins distinguish: Marten and Psarakos 1995; self-aware: Hart and Whitlow 1995.
58. Povinelli and Giambrone 2001.
59. One trial: Tschudin 2001; wrong box: Tschudin 2006.
60. Rendell and Whitehead 2001.
61. Roper 1986.
62. Killer whales: Baird 2000; bottlenose dolphins: Connor, Heithaus, and Barre 2001.
63. Ford 1989.
64. Ford 1991.
65. Deecke, Ford, and Spong 2000.
66. Christal, Whitehead, and Lettevall 1998.
67. Weilgart and Whitehead 1993.
68. Rendell and Whitehead 2003.
69. Ford 1991.
70. Bain 1986.
71. Bowles, Young, and Asper 1988.
72. Guinet 1992.
73. Guinet and Bouvier 1995.
74. Caro and Hauser 1992.
75. Rendell and Whitehead 2001.
76. Shark Bay dolphins: Connor and Mann 2006; observed since 1984: Connor, Smolker, and Richards 1992.
77. Connor and Mann 2006.
78. Connor, Smolker, and Richards 1992.
79. Harcourt and de Waal 1992.
80. Kudo and Dunbar 2001.
81. Connor and Krützen 2003.
82. Connor and Mann 2006.
83. Herman 1980.
84. Alexander 1979.
85. Connor and Mann 2006.
86. Smolker et al. 1997.
87. Biro et al. 2003; Ottoni and Mannu 2003; Weir and Kacelnik 2006.
88. Krützen et al. 2005.
89. Smolker et al. 1997.
90. Pryor et al. 1990.
91. Rendell and Whitehead 2001.
92. Marino 2002.
93. Darwin 1936[1871]:38.
94. Marten et al. 1996; McCowan et al. 2000.
95. Kuczaj and Highfill 2005.
96. Hurley and Nudds 2006.
97. Bekoff 2000a, 2000b.
98. Lautin 2001.
99. MacLeon 1970.
100. Aggleton 1992.
101. Marino 2004.
102. Allen and Bekoff 1997.
103. Bekoff 1995.
104. Bekoff 2000a.
105. Bekoff 2000a.
106. Douglas-Hamilton et al. 2006.
107. Post-traumatic stress disorder: Bradshaw et al. 2005; traumatic situations: Bradshaw and Schore 2007.
108. Williams and Lusseau 2006.
109. Bekoff 2000b.
1. Twiss and Reeves 1999; Frohoff 2007.
2. For example, Lilly 1975.
3. With the editorial assistance of his sons, Philip Hansen Bailey and Charles Lilly, in Frohoff and Peterson 2003:84.
4. Nollman 1987; Doak 1981, 1988; Wilke, Bossley, and Doak 2005.
5. Beamish 1995.
6. Lilly 1975; Nollman 1987.
7. Frohoff 1993.
8. Frohoff and Packard 1995; Frohoff 1996.
9. Boat activity: Au and Perryman 1982; Acevedo 1991; Kruse 1991; tuna-fishing operations: Norris, Stuntz, and Rogers 1978; Pryor and Shallenberger 1991.
10. Acevedo 1991; Richardson et al. 1991.
11. Purton 1978; Martin and Bateson 1986.
12. For example, Constantine 2001; Bejder and Samuels 2003; Lusseau 2003.
13. Many levels: Krebs and Dawkins 1984; Walther 1984; W. J. Smith 1991; change in behavior: Philips and Austad 1990; W. J. Smith 1990.
14. Krebs and Dawkins 1984; Walther 1984; W. J. Smith 1991.
15. Success of communication: W. J. Smith 1990; signals easily read: Walther 1984.
16. Krebs and Dawkins 1984.
17. Kiszka 2007:101.
18. Walther 1984:367.
19. Hediger 1964:163.
20. Pryor 1973; Pryor 1990b.
21. Dudzinski 2003.
22. Krebs and Dawkins 1984.
23. Dudzinski, Clark, and Würsig 1995.
24. For example, Xitco 1988; Herzing 1993; Kuczaj and Yeater 2006.
25. Frohoff, Vail, and Bossley 2005, 2006.
26. For example, Defran and Pryor 1980; Herman 1980; Herzing 1993; Dudzinski, Frohoff, and Crane 1995.
27. Frohoff 1998.
28. Fagan 1981.
29. Bekoff 1972.
30. Frohoff 1996.
31. Dudzinski 1996; Frohoff, personal observation, 1985, 1992.
32. Beach 1945.
33. We note that in some countries, including the United States, it is illegal to intentionally swim with wild dolphins (see chapter 6 for more information).
34. Norris and Dohl 1980.
35. Hankins 1993.
36. Donaldson 1982; Bel’kovich 1991; Herzing 1993.
37. Provisioned with food: National Marine Fisheries Service 1990; contact with swimmers: Lockyer 1990.
38. Samuels and Spradlin 1995.
39. Pryor 1986.
40. Pryor 1986; Frohoff 1993.
41. Frohoff 2000a, 2000b.
42. Pryor 1986.
43. Philips and Austad 1990; W. J. Smith 1991.
44. Pryor 1986.
45. Defran and Pryor 1980.
46. Frohoff 1993.
47. Frohoff 2007.
48. Differences: Taylor and Saayman 1972; similarities: Smuts 1988.
49. Taylor and Saayman 1972.
50. Smuts 1988.
51. Teleki 1972; Norris and Dohl 1980; Norris and Schilt 1988.
52. Herman 1980, 1986.
53. Worsham and D’Amato 1973.
54. Pack 1994.
55. Dolphins: Caldwell and Caldwell 1977; Nachtigal 1986; Kuznetsov 1990; Pryor 1990a; Würsig, Kieckhefer, and Jefferson 1990; primates: Goodall 1986.
56. For example, Box 1984; Würsig, Kieckhefer, and Jefferson 1990.
57. Taylor and Saayman 1972; Peters 1980; Connor 1990a, 1990b; Pryor 1990a.
58. Bel’kovich 1991.
59. Play with inanimate objects: McBride and Hebb 1948; as mechanism for sexual learning: Morgan 1968; directed toward other species: Bel’kovich 1991.
60. Frohoff and Peterson 2003; Gales, Hindell, and Kirkwood 2003.
61. Gales, Hindell, and Kirkwood 2003.
62. Gales, Hindell, and Kirkwood 2003.
63. Domning 1991; Pryor et al. 1990.
64. Lilly and Montagu 1963.
65. Frohoff, Vail, and Bossley 2006; Lockyer 1990; Wilke, Bossley, and Doak 2005.
66. Dudzinski, Frohoff, and Crane 1995; Frohoff 1996; Frohoff, Packard, and Benson 1996.
67. Hoyt 2002.
68. Samuels, Bejder, and Heinrich 2000; Gales, Hindell, and Kirkwood 2003; Samuels et al. 2003; Frohoff 2007, in press.
69. Frohoff 1996.
70. Marino and Lilienfeld 1998, 2007.
71. Humphries 2003.
72. Brensing, Linke, and Todt 2003:100.
73. B. Smith 2003; Frohoff 2003:63.
74. Marino and Lilienfeld 2007.
75. Buck and Schroeder 1990; National Marine Fisheries Service 1990; Mazet, Hunt, and Ziccardi 2004.
76. Mazet, Hunt, and Ziccardi 2004.
77. Mazet, Hunt, and Ziccardi 2004.
78. For example, “Dolphins Said to Have Rescued Fishermen,” Reuters, October 25, 1993.
79. For example, “Dolphins to the Rescue: Fellow Mammals Repel Shark, Save Surfer,” Surfer Magazine, 1993; “Dolphins Save Man in Shark Attack,” Washington Times, July 26, 1996; “Columbia Stowaways Say Dolphins Saved Their Lives,” Reuters, February 18, 1999.
80. For example, Miami Herald, January 23, 2000, April 22, 2001.
81. New Zealand Herald, November 24, 2004.
82. Frohoff 2000a; Gales, Hindell, and Kirkwood 2003.
83. Patterson et al. 1998.
84. Shane, Wells, and Würsig 1986; Wells, Scott, and Irvine 1987.
85. Hediger 1955.
86. Sweeney 1990.
87. Hediger 1964; Pryor 1973.
88. Pryor 1973.
89. Santos 1997.
90. Rose, Farinato, and Sherwin 2006.
91. Mazet, Hunt, and Ziccardi 2004.
1. Bauer and Herman 1986.
2. Defran and Pryor 1980; Pryor and Kang 1980; Au and Perryman 1982; Constantine 1995; Samuels and Spradlin 1995.
3. Norris, Stuntz, and Rogers 1978; Pryor and Kang 1980; Au and Perryman 1982; Finley et al. 1990; Acevedo 1991; Kruse 1991; Constantine 1995.
4. Constantine 1995.
5. Marine Mammal Commission 2007.
6. Richardson et al. 1998.
7. Soto et al. 2006.
8. Tyack 2003; Southall 2005.
9. Nowacek et al. 2007.
10. Marine Mammal Commission 2007.
11. Hoyt 2005; Erich Hoyt to Toni Frohoff, personal communication, July 24, 2007.
12. Erich Hoyt to Toni Frohoff, personal communication, July 24, 2007.
13. Deecke 2006.
14. Deecke 2006.
15. Morton and Symonds 2002.
16. Bob Weber, “Suffering Narwhal Opens Hidden Debate on Arctic Research Ethics,” CP Wire, June 2, 2007.
17. For example, Connor and Smolker 1985.
18. Frohoff and Peterson 2003; Gales, Hindell, and Kirkwood 2003.
19. Constantine 1995.
20. For example, Herzing 1993; Dudzinski 1996.
21. Frohoff 2000b; Gales, Hindell, and Kirkwood 2003.
22. Bejder and Samuels 2003.
23. Lusseau 2003.
24. Richter, Dawson, and Slooten 2006.
25. Forest 2001; Courbis 2004.
26. Lisa Huynh, “Dolphins Enduring More Harassment: Officials Want Tougher Viewing Rules,” West Hawaii Today; available at http://wilddolphin.org/westoahu.htm; Tori Cullins to Toni Frohoff, personal communication, 2007.
27. Frohoff 2000b; Bejder and Samuels 2003.
28. Duffus and Dearden 1992.
29. Bejder and Samuels 2003; Frohoff 2004.
30. For example, Frohoff 2000b; Constantine 2001; Williams, Trites, and Bain 2002; Bejder and Samuels 2003; Lusseau 2003.
31. Frohoff 2000b.
32. Samuels, Bejder, and Heinrich 2000; Samuels et al. 2003.
33. Frohoff 2000b.
34. Wilke, Bossley, and Doak 2005.
35. Frohoff 1993; Frohoff and Packard 1995.
36. Samuels and Spradlin 1995.
37. Kyngdon, Minot, and Stafford 2003.
38. Trone, Kuczaj, and Solangi 2005.
39. Frohoff and Peterson 2003.
40. Frohoff and Peterson 2003; Couquiaud 2005.
41. Lori Marino to Toni Frohoff, personal communication, July 16, 2007.
42. For example, Kellert 1996, 1999; Frohoff 2007.
43. Twiss and Reeves 1999.
44. For example, Couquiaud 2005; Rose, Farinato, and Sherwin 2006.
45. Dawkins 1990.
46. Hughes and Duncan 1988.
47. Dawkins 1980; Morton and Griffiths 1985.
48. Senate Select Committee on Animal Welfare 1985; Sweeney 1990.
49. Sweeney 1990.
50. Dawkins 1980.
51. Warburton 1991.
52. Meyer-Holzapfel 1968; Dawkins 1980.
53. Meyer-Holzapfel 1968; Dawkins 1980; Grier and Burk 1992.
54. Norris and Prescott 1961; Greenwood 1977; Defran and Pryor 1980; Carter 1982; Sweeney 1990.
55. Frohoff and Packard 1995; Carlson and Frohoff in preparation.
56. Kellert 1999:16.
57. Hoyt 2002.
58. Dudzinski 2003:295.
59. Dudzinski 2003:295.