20:
44:
60:
154:
casques, the growth process may take as long as six years. In general, if male and female casques of a species are similarly sized, then they tend to be differently colored, and if they are similarly colored, they tend to be differently sized. Hornbill species that live in dry, open areas tend to have smaller casques than those that live in forested areas.
299:, on the other hand, males have much larger parietal crests than females. However, the underlying bones are thin and elongated. Their enlarged crests are used in display; large crests can make the animal appear bigger. Females preferentially choose larger males, and larger males are more successful in aggressive encounters with other males.
194:
have been advanced in the past for cassowary casques – that they provide a "helmet" to protect the birds' heads as they move through the forest, that they serve as a "shovel" during foraging, or that they are used during fights with conspecifics – have now been largely discounted due to a lack of field observations confirming those uses.
193:
Heat exchange is a primary function of cassowary casques. Studies have shown that the casques efficiently shed heat at high temperatures and help to restrict heat loss at lower temperatures. Cassowaries have been seen dunking their casques into water when temperatures were high. Some theories that
162:
Casques may serve different functions in different species, and may serve multiple functions in a single species. In the hornbills, the casques of males and females of each species differ in size, shape, structure, and color, and the casques of young birds are different than those of adults. These
253:
species have casques, which in these reptiles are bony protrusions on the top of the head. In species which have casques, males tend to have significantly larger casques than females. Studies have shown that casques are used for communication, including the indication of fighting ability. In some
153:
tissue at the front of the skull. In most species, the casque is primarily hollow, with a network of bony filaments at the posterior end. The structure starts small in youngsters and develops over time, and at maturity is typically larger in males than in females. For larger species with larger
234:. Helmeted hornbills are particularly sought, as their casques are densely solid. Although they are protected by law throughout their range, they are killed at unsustainable rates; between 2011 and 2014, for example, more than 1100 skulls were seized from poachers in
254:
species, the size of the casque accurately predicts the bite strength of the individual. The casques form an attachment point for musculature; bigger casques have a larger area for muscle attachment, which can result in a stronger bite. The
79:
or the skull, either on the front of the face, or the top of the head, or both. The casque has been hypothesized to serve as a visual cue to a bird's sex, state of maturity, or social status; as reinforcement to the
289:, these modifications are present in both sexes; the thickened bones allow for greater bite strength as there is more area for muscle attachment. This may allow these species to utilize larger prey with more
190:
casque-butt both in aerial battles, and in clashes between perched and flying birds. While most instances involve two males, clashes can also occur between members of a mated pair.
84:'s structure; or as a resonance chamber, enhancing calls. In addition, they may be used in combat with other members of the same species, in the gathering of food, or in
1121:
654:
Alexander, G. D.; Houston, D. C. & Campbell, M. (May 1994). "A possible acoustic function for the casque structure in hornbills (Aves: Bucerotidae)".
1171:
Taylor, Gregory W.; Santos, Juan C.; Perrault, Benjamin J.; Morando, Mariana; Vásquez Almazán, Carlos
Roberto & Sites Jr., Jack W. (November 2017).
875:
Gamble, Kathryn C. (March 2007). "Internal anatomy of the hornbill casque described by radiography, contrast radiography, and computed tomography".
19:
982:
778:
684:
75:
is an anatomical feature found in some species of birds, reptiles, and amphibians. In birds, it is an enlargement of the bones of the
757:
67:
provides an expanded area for the attachment of jaw musculature – and may also help the animal to collect moisture or store fat.
696:"Little if any role of male gonadal androgens in ontogeny of sexual dimorphism in body size and cranial casque in chameleons"
1239:
973:
Kemp, A. C. (2001). "Family
Bucerotidae (Hornbills)". In del Hoyo, Josep; Elliott, Andrew & Sargatal, Jordi (eds.).
862:
1042:
266:
has a particularly large casque, which scientists have theorised may be used to collect moisture or store fat.
186:
also bash their casques together, sometimes in aerial combat, sometimes while one of the two birds is perched.
1091:
Naish, Darren (2015). "Book review – The ecology and conservation of Asian hornbills: farmers of the forest".
888:
808:
Eastick, Danielle L.; Tattershall, Glenn J.; Watson, Simon J.; Lesku, John A. & Robert, Kylie A. (2019).
207:
169:
131:
76:
33:
1173:"Sexual dimorphism, phenotypic integration, and the evolution of head structure in casque-headed lizards"
1234:
1060:"Morphology, ornaments and performance in two chameleon ecomorphs: is the casque bigger than the bite?"
175:, may help to strengthen a long, curved beak, which can allow a stronger bite force at the bill's tip.
1184:
821:
707:
202:
Casques are regularly subject to injury and disease. Injury can be either self-induced, or caused by
187:
43:
295:
215:
182:, for example, clash their casques together in mid-air combats that can last up to two hours. Male
118:
1108:
1046:
961:
908:
892:
163:
various differences may aid in the recognition of potential mates or competitors. Casques on the
52:
1212:
1079:
978:
900:
849:
774:
733:
680:
219:
179:
1202:
1192:
1157:
1100:
1071:
1038:
1009:
953:
884:
839:
829:
746:
723:
715:
663:
333:
313:
255:
85:
64:
1022:
328:
992:
Kinnaird, Margaret F.; Hadiprakarsa, Yok Yok & Thiensongrusamee, Preeda (July 2003).
178:
Some species use their casques for fighting with other members of the same species. Male
1188:
825:
711:
1207:
1172:
1145:
844:
809:
767:
728:
695:
667:
318:
308:
270:
223:
211:
183:
28:
222:
have long been hunted for their casques, which are used for carvings. Items made from
1228:
1013:
993:
870:. Amsterdam, the Netherlands: National Foundation for Research in Zoological Gardens.
274:
1112:
1050:
912:
965:
279:
259:
48:
1104:
203:
114:
1075:
834:
789:
719:
957:
323:
285:
238:
59:
132:
34:
250:
235:
142:
106:
1216:
1162:
1083:
921:
904:
853:
737:
356:
354:
149:
sits between the bone and the skin. Hornbill casques grow from an area of
977:. Vol. 6. Mousebirds to Hornbills. Barcelona, Spain: Lynx Edicions.
150:
146:
122:
102:
24:
896:
373:
371:
369:
167:, particularly those that run the length, or nearly the length, of the
1197:
1058:
Measey, G. John; Hopkins, Kevin & Tolley, Krystal A. (May 2009).
290:
227:
170:
552:
1059:
937:
747:
Pneumatisation and internal architecture of the southern cassowary
263:
231:
145:
layer of skin. However, in cassowaries, a foamy, elastic layer of
138:
110:
58:
42:
18:
936:
Kasambe, Raju; Charde, Pravin & Yosef, Reuven (April 2011).
164:
126:
81:
694:
Bauerová, Anna; KratochvĂl, Lukáš & KubiÄŤka, Lukáš (2020).
793:
938:"Aerial jousting and bill grappling in Indian grey hornbill (
360:
420:
418:
1043:
10.1642/0004-8038(2003)120[1062:LVBCCS]2.0.CO;2
861:
Galama, Wieke; King, Catherine & Brouwer, Koen (2002).
636:
1146:"The integumentary morphology of modern birds—an overview"
377:
101:
Casques are found in a number of species, including most
889:
10.1647/1082-6742(2007)21[38:IAOTHC]2.0.CO;2
516:
448:
745:
Brassey, Charlotte A. & O'Mahoney, Thomas (2018).
488:
486:
405:
403:
401:
388:
386:
461:
459:
457:
765:
Campbell, Bruce & Lack, Elizabeth, eds. (1985).
540:
624:
766:
576:
553:Kinnaird, Hadiprakarsa & Thiensongrusamee 2003
864:EAZA Hornbill Management and Husbandry Guidelines
504:
1122:"Aerial casque-butting in the great hornbill
1023:"Low frequency vocalizations by cassowaries (
1021:Mack, Andrew L.; Jones, Josh (October 2003).
564:
8:
125:. In most of these species, the casque is a
998:: observations from Indonesia and Thailand"
931:. Vol. 17, no. 2. pp. 96–97.
424:
810:"Cassowary casques act as thermal windows"
790:"The bird that's more valuable than ivory"
1206:
1196:
1161:
843:
833:
727:
588:
994:"Aerial jousting by helmeted hornbills
612:
378:Bauerová, KratochvĂl & KubiÄŤka 2020
350:
210:is a common issue, particularly in the
517:Alexander, Houston & Campbell 1994
449:Alexander, Houston & Campbell 1994
409:
392:
293:exoskeletons. In species of the genus
1144:Stettenheim, Peter J. (August 2000).
877:Journal of Avian Medicine and Surgery
477:
7:
600:
528:
492:
465:
436:
269:Casqueheaded lizards in the family
206:or environmental factors. Invasive
55:helps the bird to shed excess heat.
975:Handbook of the Birds of the World
679:. Saint Paul, MN: Voyageur Press.
668:10.1111/j.1469-7998.1994.tb05262.x
258:of the arid stretches of southern
226:date back more than 2000 years in
14:
788:Colwell, Mary (12 October 2015).
773:. Carlton, UK: T and A D Poyser.
625:Measey, Hopkins & Tolley 2009
1014:10.1046/j.1474-919X.2003.00188.x
577:Kasambe, Charde & Yosef 2011
31:has a distinctive casque on its
920:Kane, Robert E. (Summer 1981).
505:Galama, King & Brouwer 2002
1:
1120:Shankar Raman, T. R. (1998).
758:British Ornithologists' Union
1105:10.1080/08912963.2014.919757
541:Brassey & O'Mahoney 2018
230:and more than 1000 years in
16:Anatomical feature in birds
1256:
1076:10.1016/j.zool.2008.09.005
835:10.1038/s41598-019-38780-8
720:10.1038/s41598-020-59501-6
958:10.1007/s10211-010-0085-2
675:Badger, David P. (2006).
751:casque: a microCT study
208:squamous cell carcinoma
141:that is covered with a
121:and several species of
63:The high casque of the
68:
56:
40:
1177:Ecology and Evolution
769:A Dictionary of Birds
589:Mack & Jones 2003
188:Indian grey hornbills
62:
46:
22:
1240:Parts of a bird beak
1163:10.1093/icb/40.4.461
591:, p. 1066–1067.
216:Rhinoceros hornbills
198:Problems and threats
1189:2017EcoEv...7.8989T
826:2019NatSR...9.1966E
749:Casuarius casuarius
712:2020NatSR..10.2673B
361:Eastick et al. 2019
119:helmeted guineafowl
1150:American Zoologist
1093:Historical Biology
940:Ocyceros birostris
814:Scientific Reports
700:Scientific Reports
656:Journal of Zoology
637:Taylor et al. 2017
565:Shankar Raman 1998
220:helmeted hornbills
180:helmeted hornbills
69:
57:
53:southern cassowary
41:
1198:10.1002/ece3.3356
1183:(21): 8989–8998.
984:978-84-87334-30-6
780:978-0-85661-039-4
686:978-0-7603-2579-7
129:extension of the
1247:
1220:
1210:
1200:
1167:
1165:
1140:
1130:
1124:Buceros bicornis
1116:
1087:
1054:
1037:(4): 1062–1068.
1017:
988:
969:
932:
929:Gem and Gemology
926:
922:"Hornbill Ivory"
916:
871:
869:
857:
847:
837:
804:
802:
800:
784:
772:
761:
755:
741:
731:
690:
671:
640:
634:
628:
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610:
604:
598:
592:
586:
580:
574:
568:
562:
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550:
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532:
526:
520:
514:
508:
502:
496:
490:
481:
475:
469:
463:
452:
446:
440:
434:
428:
425:Stettenheim 2000
422:
413:
407:
396:
390:
381:
375:
364:
358:
334:Wattle (anatomy)
314:Crest (feathers)
277:. In the genera
256:veiled chameleon
172:
134:
86:thermoregulation
65:veiled chameleon
36:
1255:
1254:
1250:
1249:
1248:
1246:
1245:
1244:
1225:
1224:
1223:
1170:
1143:
1128:
1119:
1090:
1057:
1020:
996:Rhinoplax vigil
991:
985:
972:
946:Acta Ethologica
935:
924:
919:
874:
867:
860:
807:
798:
796:
787:
781:
764:
753:
744:
693:
687:
674:
653:
649:
644:
643:
639:, p. 8996.
635:
631:
623:
619:
611:
607:
599:
595:
587:
583:
575:
571:
563:
559:
551:
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435:
431:
423:
416:
408:
399:
391:
384:
376:
367:
359:
352:
347:
342:
329:Snood (anatomy)
305:
247:
200:
184:great hornbills
174:
160:
136:
99:
94:
38:
17:
12:
11:
5:
1253:
1251:
1243:
1242:
1237:
1227:
1226:
1222:
1221:
1168:
1156:(4): 461–477.
1141:
1117:
1099:(7): 954–956.
1088:
1070:(3): 217–226.
1055:
1018:
1008:(3): 506–508.
989:
983:
970:
933:
917:
872:
858:
805:
785:
779:
762:
742:
706:(2673): 2673.
691:
685:
672:
650:
648:
645:
642:
641:
629:
627:, p. 217.
617:
605:
593:
581:
569:
567:, p. 123.
557:
555:, p. 506.
545:
533:
531:, p. 451.
521:
509:
497:
495:, p. 450.
482:
480:, p. 954.
470:
468:, p. 449.
453:
441:
439:, p. 436.
429:
427:, p. 465.
414:
397:
382:
365:
349:
348:
346:
343:
341:
338:
337:
336:
331:
326:
321:
319:Frontal shield
316:
311:
309:Comb (anatomy)
304:
301:
275:parietal bones
273:have expanded
271:Corytophanidae
246:
243:
241:region alone.
224:hornbill ivory
212:great hornbill
199:
196:
168:
159:
156:
133:upper mandible
130:
98:
95:
93:
90:
77:upper mandible
51:casque of the
35:upper mandible
32:
29:great hornbill
15:
13:
10:
9:
6:
4:
3:
2:
1252:
1241:
1238:
1236:
1233:
1232:
1230:
1218:
1214:
1209:
1204:
1199:
1194:
1190:
1186:
1182:
1178:
1174:
1169:
1164:
1159:
1155:
1151:
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1138:
1134:
1127:
1125:
1118:
1114:
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1098:
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1089:
1085:
1081:
1077:
1073:
1069:
1065:
1061:
1056:
1052:
1048:
1044:
1040:
1036:
1032:
1028:
1026:
1019:
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1007:
1003:
999:
997:
990:
986:
980:
976:
971:
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963:
959:
955:
951:
947:
943:
941:
934:
930:
923:
918:
914:
910:
906:
902:
898:
894:
890:
886:
882:
878:
873:
866:
865:
859:
855:
851:
846:
841:
836:
831:
827:
823:
819:
815:
811:
806:
795:
791:
786:
782:
776:
771:
770:
763:
759:
752:
750:
743:
739:
735:
730:
725:
721:
717:
713:
709:
705:
701:
697:
692:
688:
682:
678:
673:
669:
665:
661:
657:
652:
651:
646:
638:
633:
630:
626:
621:
618:
614:
609:
606:
603:, p. 96.
602:
597:
594:
590:
585:
582:
579:, p. 14.
578:
573:
570:
566:
561:
558:
554:
549:
546:
542:
537:
534:
530:
525:
522:
519:, p. 57.
518:
513:
510:
507:, p. 10.
506:
501:
498:
494:
489:
487:
483:
479:
474:
471:
467:
462:
460:
458:
454:
451:, p. 59.
450:
445:
442:
438:
433:
430:
426:
421:
419:
415:
412:, p. 38.
411:
406:
404:
402:
398:
395:, p. 19.
394:
389:
387:
383:
379:
374:
372:
370:
366:
362:
357:
355:
351:
344:
339:
335:
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327:
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312:
310:
307:
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261:
257:
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233:
229:
225:
221:
217:
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209:
205:
197:
195:
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185:
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176:
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155:
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148:
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128:
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116:
112:
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96:
91:
89:
87:
83:
78:
74:
66:
61:
54:
50:
45:
37:
30:
26:
21:
1235:Bird anatomy
1180:
1176:
1153:
1149:
1136:
1132:
1123:
1096:
1092:
1067:
1063:
1034:
1030:
1024:
1005:
1001:
995:
974:
952:(1): 13–15.
949:
945:
939:
928:
883:(1): 38–49.
880:
876:
863:
817:
813:
797:. Retrieved
768:
748:
703:
699:
676:
662:(1): 57–67.
659:
655:
632:
620:
613:Colwell 2015
608:
596:
584:
572:
560:
548:
543:, p. 1.
536:
524:
512:
500:
473:
444:
432:
294:
284:
280:Corytophanes
278:
268:
260:Saudi Arabia
249:A number of
248:
204:conspecifics
201:
192:
177:
161:
151:vascularized
100:
72:
70:
49:vascularized
27:, this male
820:(1): 1966.
410:Gamble 2007
393:Badger 2006
236:Indonesia's
115:horned guan
107:cassowaries
1229:Categories
1139:: 123–124.
756:(Report).
478:Naish 2015
340:References
324:Neck frill
296:Basiliscus
286:Laemanctus
239:Kalimantan
47:The bony,
23:Like most
1025:Casuarius
601:Kane 1981
529:Kemp 2001
493:Kemp 2001
466:Kemp 2001
437:Kemp 2001
345:Citations
291:chitinous
251:chameleon
158:Functions
143:cornified
103:hornbills
97:Structure
25:hornbills
1217:29177036
1133:Forktail
1113:84065368
1084:19230632
1051:86025843
913:19495666
905:18069170
897:27823461
854:30760849
799:27 April
738:32060387
303:See also
245:Reptiles
147:collagen
123:curassow
1208:5689487
1185:Bibcode
1064:Zoology
1031:The Auk
966:1691573
845:6374359
822:Bibcode
729:7021717
708:Bibcode
677:Lizards
647:Sources
1215:
1205:
1111:
1082:
1049:
1027:spp.)"
981:
964:
911:
903:
895:
852:
842:
777:
736:
726:
683:
228:Borneo
171:culmen
117:, the
113:, the
109:, the
105:, all
73:casque
1129:(PDF)
1109:S2CID
1047:S2CID
962:S2CID
925:(PDF)
909:S2CID
893:JSTOR
868:(PDF)
754:(PDF)
264:Yemen
232:China
139:skull
111:maleo
92:Birds
1213:PMID
1080:PMID
1002:Ibis
979:ISBN
901:PMID
850:PMID
801:2021
775:ISBN
734:PMID
681:ISBN
283:and
262:and
218:and
165:bill
127:bony
82:beak
1203:PMC
1193:doi
1158:doi
1101:doi
1072:doi
1068:112
1039:doi
1035:120
1010:doi
1006:145
954:doi
885:doi
840:PMC
830:doi
794:BBC
724:PMC
716:doi
664:doi
660:233
137:or
1231::
1211:.
1201:.
1191:.
1179:.
1175:.
1154:40
1152:.
1148:.
1137:13
1135:.
1131:.
1107:.
1097:27
1095:.
1078:.
1066:.
1062:.
1045:.
1033:.
1029:.
1004:.
1000:.
960:.
950:14
948:.
944:.
942:)"
927:.
907:.
899:.
891:.
881:21
879:.
848:.
838:.
828:.
816:.
812:.
792:.
732:.
722:.
714:.
704:10
702:.
698:.
658:.
485:^
456:^
417:^
400:^
385:^
368:^
353:^
214:.
88:.
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