A Practical Challenge for Atlasers: Identifying Juvenile Birds

Transcription

1 A Practical Challenge for Atlasers: Identifying Juvenile Birds

2 Ageing sequence for birds: After hatching, a young bird s first plumage is called natal down. Prejuvenal (or postnatal) molt Juvenile (or juvenal) plumage typically acquired while in the nest (except precocial spp). This plumage includes body, wings and tail feathers. Held for a short period of time on natal/breeding grounds. Prebasic I molt Basic I (winter) plumage typically held during first fall and winter. Body feathers only wing and tail feathers are retained (for about a year). Prealternate I molt First Alternate (breeding) plumage (typically held until mid/late summer). Complete molt Basic II or Definitive Basic (winter) plumage

3 American Robin plumages (examples not true colors)

4 Immature plumages Term is very broad/inclusive Basically can include every plumage from fledgling up until they become full adult In some cases the term immature might just apply for the first year (or months): In other birds like gulls or eagles the immature term might apply for several years:

5 First plumage - natal down Indigo Bunting new nestlings

6 Eastern Phoebe nestlings

7 nestling (either in downy or juvenile plumage)

8 Juvenile plumage

9 fledgling (typically juvenile plumage)

10

11 Eastern Phoebe nestlings

12

13 Eastern Phoebe juvenile

14

15 Eastern Phoebe juvenile

16 Eastern Phoebe first basic (fall/winter)

17 Chipping Sparrow

18 Chipping Sparrow juvenile

19 Chipping Sparrow first basic (fall/winter) plumage

20 Song Sparrow juvenile and adult

21

22 Song Sparrow juvenile

23 Swamp Sparrow

24 Swamp Sparrow juvenile

25 Grasshopper Sparrow juvenile

26 Henslow s Sparrow juvenile

27 Henslow s Sparrow juvenile

28 Nick Anich Jenny Wenzel Vesper Sparrow juvenile

29 Yellow-rumped Warbler - juvenile

30 Yellow-rumped Warbler - juvenile

31 Yellow-rumped Warbler - juvenile

32 Yellow-rumped Warbler - first basic (fall/winter)

33 Common Yellowthroat juvenile

34 Common Yellowthroat juvenile

35 Common Yellowthroat molting from juvenile to first basic

36

37 Common Yellowthroat molting juvenile to first basic (fall/winter)

38 American Redstart juvenile David Franzen

39

40 American Redstart juvenile

41 American Redstart first basic (fall/winter)

42 Ovenbird - juvenile

43 Ovenbird - juvenile

44 Ovenbird juvenile

45 Ovenbird juvenile

46 Only one warbler with white tail spots across center of tail Magnolia

47 Magnolia Warbler first basic (fall/winter)

48 Canada Warbler juvenile

49

50 Palm Warbler juvenile

51 Palm Warbler first basic (fall/winter)

52 Only one warbler has extensive yellow tail spots Yellow Warbler

53 Yellow Warbler juvenile

54 Yellow Warbler juvenile

55 Yellow Warbler first basic (fall/winter)

56

57 Rose-breasted Grosbeak juvenile

58 Rose-breasted Grosbeak first basic (fall/winter)

59 Rose-breasted Grosbeak immature male (left) & female (right)

60 Ryan Brady Pine Siskin juvenile

61 Barn Swallow juvenile

62 Horned Lark juvenile

63 Some juveniles are fairly straightforward color patterns are very much like adults

64 House Wren juvenile

65 House Wren juvenile

66 Black-capped Chickadee juvenile

67 Gray Catbird juvenile

68 Cedar Waxwing juvenile

69 Cedar Waxwing juvenile

70 Eastern Kingbird juvenile

71 Brown Thrasher juvenile

72

73 Eastern Bluebird juvenile Jeff Galligan

74 Wood Thrush juvenile

75 Blue Jay juvenile

76

77 American Crow juvenile Ryan Brady

78 Red-winged Blackbird juvenile

79 Northern Cardinal juvenile

80

81 Great Crested Flycatcher juvenile

82 Baltimore Oriole juvenile

83

84 Downy Woodpecker juvenile male

85 Downy Woodpecker juvenile female

86 Mourning Dove juvenile

87 Great Horned Owl juvenile

88 Precocial birds attain downy plumage while in egg Killdeer hatchling downy young, attains juvenile plumage by about 17 days

89 Wild Turkey hatchlings

90 Wild Turkey fledgling (young roost in trees by 2 weeks)

91 Wood Duck brood with female

92 Sandhill Crane baby with parents

93 Chipping Sparrow juvenile

94

95 Dark-eyed Junco

96 Ryan Brady Nashville Warbler

97 Ryan Brady American Redstart

98 Brown-headed Cowbird juvenile

99 Brown-headed Cowbird with foster parent Yellow Warbler

100 Brown-headed Cowbird with foster parent Chipping Sparrow

101 David Franzen

102 Black-billed Cuckoo juvenile with adult David Franzen

103 Black-billed Cuckoo juvenile

104 Black-billed Cuckoo immature

105 Yellow-billed Cuckoo - juvenile

106 Yellow-billed Cuckoo immature

107

108 So, the bottom line is if you see a juvenile bird that you don t recognize, be very patient and wait and watch it for a while. One of its parents will likely come to feed it before long!

109 Applicable codes from the WBBA II handbook: Obviously, the use of these codes is a judgment call. Look for clues of immaturity such as: Tufts of down anywhere on the body. Short tail feathers not yet fully grown. Not yet capable of strong flight. Appearance of loose or fluffy plumage. Streaks on underparts that may not be present later = juvenile.

110 Questions or comments?