Vol. 5, No. 2; Spring 1983 - North American Bluebird Society

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Table 1. Arthropod Occu pants o f Nest s of Eastern Bluebirds. For ag i ng habl t s Family (co mmon name ) Number ! Prop or t ion of occupied nests occupied n e s ~ p a r a s~ [ ~c on ve r[ebra ce s De rtaa ny s s i. da e 1. 00 5381, . 0 pa r a s i ~i c on ve r t e br a ce s Calliphoridae (bl ov f l i es ) 0 . 31 1,.8 pa r a s ~ tic on bl owfl i es l c hneumonidae (ichn eumon ~a s p s) 0. 31 11 . 8 p a r a s ~ ( ic on ichneumon was ps par as i[e par asite Per l ampidae (c halci d ~a s p s ) ~ e no p o n i d ae (bird lice ) Philop t e r idae (bi rd lice ) 0. 51, 5 .9 0 . ~ 6 10 . 0 0 . 23 4 . 3 de t r i t i 'lore Pyroglyphidae 1. 00 1762 . 8 de r.r i ci VQ re Ps yl l ipsocidae (book lice ) 0 . 46 ~ . O de t r i t ivor e Cecidomyi i dae (gall mi dges ) 0.5 4 7. 9 de t r i t ivo re Bi bionidae (march Elies ) 0 . 31 8 . 5 de t ri t ivo re Xyce l opb i l i da e (fungus gnacs ) 0 . 31 12 .2 de r r i r i vo re Syl vani da e ( f l a t ba r k bee tles ) 0.5 !. 7.6 pre da to r Sa lci cidae (j ump ing spi ders ) 0. 54 7. 1 preda cor Forini ci dae (an t s) 0 . 77 13 . 9 Ic h n e u m o n wasps (Ic hneumonidae, Table 1) parasitize bl owflies and chalcld wasps (Perlarnpidae, Table 1) parasitize Ichneumon was ps. None o f the four nests containing adu lt ichneumon wasps co nt ained blo wflies . Although bird lice (Menoponidae and Philopteridae, Table 1) may sca venge more than pa rasitize, they are obligate residents on the bird 's bod y. Thei r infrequent occ urrence and small nu mbers represent indi viduals that fell from an adul t or nest li ng. Detritivores The family Pyroglyphidae was represented in all nests (Table 1) by a single spe cies, Dermatophagofde s evansi (Fig. 3), th at remains in the nest wh ere it feeds on fecal material from th e nestlings, flakes of feat her sheaths that fall int o the nest , and other organic deb ris (Krantz 1978). Such foods are referred to as detritu s and detrit ivores are anim als t hat consu me detritus Popu lat ions of D. evan- 54 Sf, like th ose of D. hirundinus , the blood -suc king mite, were strongly and posttlve ly correlat ed with brood size (Fig. 2). Book li ce (Psyillipsoc.dae, Table 1), als o scavenge detritus (Borror et al. 1976), however their numbe rs were only weakly correlated with brood size (r = 0.422). The remain ing fami lies of detrilivo res repr esent insects that feed on dead or decayin g vegetation. All were presumably attracted to t he nest materials whi ch pro vid e an abundant supply of fo od. Neither the occ urrence nor the number of these det rit lvor es was co rrelated w ith brood size or volume of the nest material. Predators Jumping spiders (Sa lt ic id ae . Table 1) are sol itary predators of smal l arthropods. Thos e fou nd were probabl y reside nt in the nests occ upied. Ant s (Formicidae, Tabl e 1), on the other hand , are colonial predators. Si nce only wo rkers were found, they were probab ly not resid ents of the nest. They Sialla, Spring 1983
Figure 1. A dorsal view of Dermanyssus ntrunotnus, the blood-sucking mite, shows its eight legs, four on each side of the body, and the much smaller palps with which it pierces the nestlings ' skin to obtain its blood meal. The body is covered with numerous, small sensory hairs. Despite its adaptations for climb ing and feeding on nestlings , D. hir undinus is unable lo cling to humans or pierce our much thicker skin. MOUTHPARTS LE GS may have been carried in on nest materia l or ent ere d while foraging from a nearby col ony. The latt er seems unli kely, howe ver, as all nests were mounted on greased, metal poles. Neith er predat or showed any correlat ion with brood size, nest volume, or total number of arthropods inhabiting the nest. DISCUSSION Previous authors have reported an incidence of blowfly larvae between 82% (Pinkowski 1977) and 94% (Mason 1944), with individual nests frequently containing 150-200 larvae. The low incidence of blowfly larvae in the present Volume5, Number2 st udy (Table 1) may be due to light, dry , well-ventilated nestboxes. Alternatively, Tree Swallows (Iridoprocne bicolor) wh ose nest s were abundant along the bluebird trail may have effect ively preyed upon the ponderous bl owfly adults, significantly reducing t he cal liphorid population. The lack of correlation among most arthropods and their food source, whether nestlings, other arthropods, or vegetation in the nest, suggests that for most occupants of the nest ecosystem dispersal is the limiting factor. Both species of mite can remain on the bird's body (Krantz 1978), and may initially enter the nest fr om an adult bi rd. Mites also overwinter in the nest 55
Page 1 and 2: 8ia ia Volume 5, Number 2 Spring 19
Page 3 and 4: 8 ialia The Quarterly J o u rnal Ab
Page 5 and 6: History of Bluebird Conservation Fo
Page 7 and 8: ing box es and th us protects the n
Page 9 and 10: an exc ellent review of th e origin
Page 11 and 12: Ill in oi s' Calh oun County was ma
Page 13 and 14: Co mpany have established trail s o
Page 15: Invertebrate Fauna of Eastern Blueb
Page 19 and 20: Figure 3. A dorsal view of Dermatop
Page 21 and 22: song to attempt to attract a mate.
Page 23 and 24: Cultu re-Does well on most soils ex
Page 25 and 26: 0 Ta bl e 1. 1982 Blue bi rd N eslb
Page 27 and 28: Grant's Folly Jon E. Boone ~ '..~ :
Page 29 and 30: the growt h of the young. In any ev
Page 31 and 32: Blueb ird Trail Directory Bluebi rd
Page 33 and 34: SASKATCHEWAN Saskatoon , Saskatchew
Page 35 and 36: A Californ ia Bluebird Story We mov
Page 37 and 38: Dealing with the Effects of Cold We
Page 39 and 40: th e ca bbage worms off my cabbaget
Page 41 and 42: 12 of the 3·inch ro und patches w
Page 44: Founded in 1978, THE NORTH AMERICAN

Vol. 5, No. 2; Spring 1983 - North American Bluebird Society

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