Behavioral Interactions between Fire Ants and Vertebrate Nest Predators at Two Black-Capped Vireo Nests

2004·2.7 MB·English

by  Jennifer E Smith

Wilson Bulletin, 116(2), 2004, pp. 163-166
BEHAVIORAL INTERACTIONS BETWEEN EIRE ANTS AND
VERTEBRATE NEST PREDATORS AT TWO BLACK-CAPPED
VIREO NESTS
JENNIFER E. SMITH, STEVEN J. TAYLOR,''^ CHRISTOPHER J. WHELAN,'
MICHAEL L. DENIGHT,^ AND MIKE M. STAKE’"
—
ABSTRACT. We report on behavioral interactions between fire ants (Solenopsis invicta) and vertebrate
predators at two Black-capped Vireo (Vireo atricapilla) nests at Fort Hood, Texas. In the presence offire ants,
an eastern woodrat {Neotomajioridcina) failed to depredate a clutch ofvireo eggs at one nest, while a rat snake
(Elciphe obsoleta lindheimeh) depredated nestlings at another nest, despite fire ants swarming the nest. Neither
nest was successful. Direct and indirect effects of interactions among nest predators on avian nesting success
need further assessment. Received 21 November2003, accepted 7June 2004.
The red imported fire ant {Solenopsis invic- ators for vertebrate prey, however, has not
ta) is an invasive species that occurs through- been documented except in the recent case
out much ofthe southern United States (Porter where fire ants consumed shrike-cached food
et al. 1991, Callcott and Collins 1996, (Allen et al. 2001). Here, we document the
O’Keefe et al. 2000), where it poses a serious behavioral interactions between fire ants and
threat to terrestrial communities (Wojcik et al. two vertebrate nest predators, an eastern
2001, Hoiway et al. 2002). It preys upon birds woodrat {Neotomafloridana) and a Texas rat
(Sikes and Arnold 1986, Allen et al. 1995, snake {Elaphe obsoleta lindheinieri), at two
Kopachena et al. 2000), small mammals (Kil- nests of the Black-capped Vireo {Vireo atri-
lion et al. 1995, Ferris et al. 1998), and rep- capilla).
tilian eggs and hatchlings (Mount et al. 1981,
Buhlmann and Coffman 2001, Parris et al. METHODS
2002). Fire ants may reduce population den-
Predator activity was recorded as part of
sities of small mammals (Killion et al. 1995, ongoing monitoring and management of
Fmearrmimsaelt aflo.ra1g9i9n8g) paantdtercnasus(eHoshlitfctsamipn estmaalll. hBalacmkil-ictaaprpyedinVsitraleloastiaotnFoirntBHeolold,anadn 8C8o,r5ye0l0l-
1997). Tuberville et al. (2000) suggest that fire counties, Texas (30° 10' N, 97° 45' W).
ants also may influence snake populations, but
Twelve infrared video systems (Fuhrman Di-
there is no evidence that they depredate adult versified, Inc., .Seabrook, Texas) were de-
snakes. Fire ants appear to out-compete native
ployed to monitor 142 nests for 1,589 expo-
ants and arthropods for invertebrate prey (Ap-
sure days (773 in the incubation stage and 816
per.son and Powell 1984, Morri.son 2002).
Competition between fire ants and other pred- i1n99t8he-2n0e0s1t.linAg dsettaagiel)edfrdoemscr1iApptriioln otof3t1he.Ivnildy-.
eo-monitoring protocol is given in .Stake and
' Center for Biodiversity, Illinois Natural History Cimprieh (2003). We quantified predation
.Survey, 607 F. Peabody Dr., Champaign, IF 61820, events and predator interactions when fire ants
USA.
were at vireo nests. Vireo behavior was eate-
CUFS:“ARH.Ln,gi2n9e0e2r NReeswemaarrckh Ia7rn.,d CD'heavmeplaoipgmn,entII, C6'1en8t2e2r,, gsoerriv/eeddinasthaeerviaildedoefmeonnsietowrhaetnlebaisrtdsonwceerewoitbh--
^The Nature C’onservancy ofTexas, P.O. Box .SI00, in a 20-sec interval and perchctl on the focal
Fort Hood, TX 76344, USA. nest for no longer than 2 sec. During aerial
‘Current address: Dept, ol /oology, 303 Natural defense, vireos actively pecked at and re-
.Science Bldg., Michigan .State Univ., Fast Lansing, Ml moved lire ants swarming the nest.
48824, USA.
'Current address: Hawks Aloft, Inc., P.O. Box Ants from \ireo nests were identified in the
10028, Albutiuerque, NM 87184, USA. field as fire ants (by MM.S) during daily main-
'’Corresponding author: e-mail: tenanee of video cameras. In a separate study,
.sjtaylor inhs.uiuc.edu .S.rr (unpubl. data) eolleeted ant samples
163
164 THE WILSON BULLETIN • Vol. 116, No. 2, June 2004
across Fort Hood at 135 points on a 2,000-in tigated the exposed clutch of eggs 0.83 min
grid, and also conducted bi-monthly ant sam- after the female abandoned the nest. While fire
pling for one year at 150 bait trap stations in ants were present on the nest and eggs, the
vireo nesting habitat. This vouchered material woodrat made physical contact with the eggs
was identified in the laboratory, and the only but did not depredate any ofthem. The wood-
Solenopsis species in these samples was S. in- rat remained at the nest for 0.37 min before
victa. On rare occasions the native fire ant, S. leaving. Ants continued to swarm the nest
geminata, has been collected at bait stations both during and after the time that the woodrat
in other studies at Fort Hood (C. E. Pekins was at the nest.
pers. comm.), leaving open the remote possi- Shortly after sunrise (05:30:02) the next
bility that the ants observed in our study could day, an adult male vireo arrived at the nest
have been native fire ants. while fire ants continued to swarm the clutch.
He immediately engaged in aerial defense of
RESULTS
the nest. He continued this behavior for 24.97
Of 134 vireo nests, 48 (35.8%) failed due min before attempting to incubate the clutch.
to direct predation, where predators removed The male switched between incubating and
or damaged some or all of the nest contents rapid pecking behaviors for another 24.03 min
(Stake and Cimprich 2003). Eire ants were before abandoning the nest. At the time of
among these predators and they directly dep- abandonment, fire ants remained at and con-
redated 15 nests (31.3%). Abandonment by tinued to swarm the nest. Despite the failed
vireos in response to fire ants was the source predation attempt by the woodrat and nest de-
of failure at six additional nests. Thus, fire fense by the adult vireos, the ants remained at
ants caused failure at 21 nests (29.6%) when the nest for a total of 29.55 hr. The clutch
direct predation and abandonment were com- failed to hatch. Careful examination of the
bined. eggs later revealed that one egg had a small
All depredated nests, except three, were at- hole in it. The egg was presumably nicked by
tacked by a single predator. In the first nest, a the woodrat as fire ants are apparently unable
Brown-headed Cowbird {Molothriis ater) re- to puncture intact egg shells, though they do
moved one nestling, and 2 days later a snake forage on pipped or cracked eggs (Ridlehuber
consumed the remaining nestlings. At the sec- 1982, Buhlmann and Coffman 2001; this
ond nest, an eastern woodrat failed to depre- study).
date a clutch of vireo eggs in the presence of At another vireo nest containing three, 8-
swarming fire ants. At the third nest, a rat day-old nestlings, an adult female vireo was
snake depredated vireo nestlings in the pres- last seen at 19:36:59 on 16 June 2000. This
ence of fire ants. Interactions of predators at nest was located 0.74 m high in a Texas oak
the second and third nest are discussed below. {Q. biickleyii). Fire ants swarmed the nest at
Based on careful examination of the video 01:03:38 on 17 June, while all three nestlings
tapes, we estimate that hundreds of fire ants were apparently sleeping and no adult birds
swarmed each of these nests. were present. Beginning 16.70 min after the
On 15 June 1999, fire ants were observed ants were first observed at the nest, the nest-
in a vireo nest at 1 1:17:02 CST while the adult lings began to squirm and move frantically
female was apparently sleeping and incubat- from side to side and continued to do so for
ing her clutch offour eggs. The nest was 1.05 the next 3.55 hr. At 04:48:20, a rat snake ar-
m high in a shin oak {Querciis sinuatci var. rived at the nest, which was still swarming
breviloba). The female vireo started to peck with ants. The snake investigated the nest for
at the ants 5.22 min after they arrived at the 2.65 min before striking and consuming a vir-
nest. Beginning 15.27 min after the arrival of eo nestling at 04:50:59. The snake proceeded
the ants, the female perched on the rim of the to depredate the other two nestlings at 04:57:
nest and rapidly pecked to remove the ants. 57 and 05:03:00 (9.62 min and 14.67 min af-
She actively removed ants for 2.05 min, after ter arriving at the nest). The snake did not
which she abandoned the nest and was not appear to be affected by the ants. The snake
observed again. left the nest at 05:15:04, with ants continuing
An eastern woodrat approached and inves- to swarm the now empty nest.
Smith et al. • ANTS AND VERTEBRATE PREDATORS AT VIREO NESTS 165
At 05:18:05, an adult female vireo returned positive and negative indirect effects are also
to the empty nest, where ants were still likely. Study of the potential indirect effects
swarming. She engaged in aerial defense for of hre ant depredation of vireos and co-oc-
15.58 min until an adult male vireo arrived at curring bird species should be a component of
05:33:40. At this time, both adults continued future studies of bird/hre ant interactions.
to defend the nest, alternating in aerial defense
ACKNOWLEDGMENTS
of the nest. Fire ants were last observed at the
nest at 07:05:31 and both adults abandoned We are grateful to the Texas Nature Conservancy
the nest at 07:06:43. and Natural Resources Branch of Fort Hood for co-
operation and assistance, especially from J. D. Cor-
DISCUSSION
nelius, C. E. Pekins, P. M. Cavanagh, and S. Jester.
Fire ants caused nest failure during this Useful insights were provided by S. K. Robinson. D.
study by swarming vireo nests (resulting in O. Ribble and E. J. Heske identified the woodrat. E.
nest abandonment) and by direct predation of wL.orMk.osReerseaanrdchMw.asJ.fMunedyeedrtchornoturgihbuctoeodpetroatliavbeoraagtreoer-y
nestlings. Our two observations of behavioral ment DPW-ENV 97-A-OOl between the Departmentof
interactions between predators suggest that the Army and The Nature Conservancy; additional
fire ants may contribute both positively and funds were provided through Engineer Research and
negatively to the nesting success of vireos. In Development Center and the Department ofthe Army
two predation attempts, fire ants apparently under DACA88-99-D-0002-14. Information contained
deterred a mammalian predator, but not a in this paper does not necessarily reflect the position
or policy of The Nature Conservancy or the federal
snake, from depredating a vireo nest. government, and no official endorsement should be in-
Because hre ants also impact other species, ferred.
including those that may depredate vireo
nests, there are a number of possible indirect LITERATURE CITED
effects of hre ants on vireos. Fire ants may
Allen, C. R., R. S. Lutz, and S. Demarals. 1995. Red
indirectly reduce rodent populations through imported fire ant impacts on Northern Bobwhite
competition forcommon food sources (Killion populations. Ecological Applications 5:632-638.
et al. 1995, Ferris et al. 1998). Fire ants are Allen, C. R., R. S. Lutz, T. Lockley, S. A. Phillips,
known to prey upon small mammals (Killion Jr., and S. Demarals. 2001. The non-indigenous
et al. 1995, Ferris et al. 1998), and they may ant, Solenopsis invicta, reduces Loggerhead
alter small mammal habitat use (Pedersen et Shrike and native insect abundance. Journal of
Agriculture and Urban Entomology 18:249-259.
al. 2003) and foraging patterns (Holtcamp et Apper.son, C. S. and E. E. Powell. 1984. Foraging
al. 1997) in ways that deter rodents from dep- activity of ants (Hymenoptera: Formicidae) in a
redating vireo nests. Fire ants depredate pasture inhabited by the red imported fire ant.
pipped eggs and hatchlings of reptiles (Mount Florida Entomologist 67:383-393.
et al. 1981, Tuberville et al. 2()0(), Buhlmann Buhlmann, K. A. and G. Coffman. 2001. Eire ant
and Coffman 2001, Parris et al. 2002), which predation of turtle nests and implications for the
strategy ofdelayed emergence. Journal ofthe Eli-
could alter snake densities and, ultimately, sha Mitchell Scientific Society 1 17:94-100.
rates of vireo predation. Callcoit, a. a. and H. L. Collins. 1996. Invasion
' Other indirect effects may result from the and range expansion of imported fire ;ints (Hy-
interaction between fire ants and vireos them- menoptera: Formicidae) in North .America from
I selves. When fire ants swarm vireo nests, they 1918-1995. l-lorida Entomologist 79:240 251.
I induce alarm responses from adult and nest- Ferris. D. K., M. .1. Kii i ion. K. P. Firris. W. \i.
I Grani, and S. B. Vinson. 1998. Influence of rel-
ling vireos. Aerial defense by adults, and pan-
I ic response by nestlings, may attract other antoipvseisabinuvnidcalan)ceonofsmarleld mimapmomrateldcaliprteuraenst.s.iSSooultrh--
I
' predators, including snakes, to the nest. Al- western Naturalist 43:97 KM).
I though fire ants apparently are unable to Iloi i( AMP. W. N.. \\. F:. Grani. and S. B. \ inson.
' breech intact eggs (Ridichuber 1982. Buhl- 1907. Patch use under preilation hazard: effect of
mann and Coffman 2001, .Stake and C'imprich the rerl importeil fire ant on deer mouse foraging
beha\ior. Ideology 78:308 317.
' 2ne0s0t3l)i,ngtshe(yStaarkeeaabnled tCoimdpeprriecdhat2e00y3o)u.ng vireo 1loi wAN\AD.T.I).J.AC.a.siL...I.2\0(0H2...AT.hVe cSaius\eksi/a.nNd.coD.nseFisi|uiesnici.
Fire ants negatively affect nest success di- es of ant iinasions. .Annual Re\ie\s ol Fx'ologN
rectly via depredation and abaiulonmcnt: both and .Sysiematies VLI8I 233.
166 THE WILSON BULLETIN • Vol. 116, No. 2, June 2004
Killion, M. J„ W. E. Grant, and S. B. Vinson. 1995. Vinson, J. B. Martin, M. T. Longnecker, C. L.
ResponseofBaiomystayloritochanges indensity Barr, and B. M. Drees. 2003. Effect ofred im-
of imported fire ants. Journal of Mammalogy 76; ported fire antson habitatusebyhispidcottonrats
141-147. (Sigmodon hispidus) and northern pygmy mice
Kopachena, J. G., a. G. Buckley, and G. A. Potts. (Baiomys taylori). Southwestern Naturalist 48:
2000. Effects of the red imported fire ant {Sole- 419-426.
nopsis invicta) on reproductive success of Barn Porter, S. D., A. Bhatkar, R. Mulder, S. B. Vinson,
Swallows (Hirundo rustica) in northeast Texas. AND D. J. Clair. 1991. Distribution and density
Southwestern Naturalist 45:477-482. of polygyne fire ants (Hymenoptera: Formicidae)
Morrison, L. W. 2002. Long-term impacts of an ar- in Texas. Journal of Economic Entomology 84:
thropod-community invasion by the imported fire 866-874.
ant, Solenopsis invicta. Ecology 83:2337-2345. Ridlehuber, K. T. 1982. Fire ant predation on Wood
Mount, R. H., S. E. Trauth, andW. H. Mason. 1981. Duck ducklings and pipped eggs. Southwestern
Predation by the red imported fire ant, Solenopsis Naturalist 27:222.
ilnizvaircdtaC(hHeymmiednoopphtoerruas:sFeoxrlmiinceiadtaues)(,Soqnuaemgagtsa:ofTtehie- Sikesf,ireP.aJn.tan(SdolKe.nopAs.isArinnovlicdt.a)19p8r6e.datRieodn iomnpoCrltiefdf
idae). Journal of the Alabama Academy of Sci- Swallow (Hirundo pyrrhonota) nestlings in east-
central Texas. Southwestern Naturalist 31:105-
ence 52:66-70.
106.
O’Keefe, S. T, J. L. Cook, T. Dudek, D. F. Wunne- Stake, M. M. and D. A. Cimprich. 2003. Using video
BURGER, M. D. Guzman, R. N. Coulson, and S. to monitor predation at Black-capped Vireo nests.
B. Vinson. 2000. The distribution of Texas ants. Condor 105:348-357.
Southwestern Entomologist 22(Supplement):1-
Tuberville, T. D., j. R. Bodie, J. B. Jensen, L. La-
92. CLAIRE, AND G. J. WHITFIELD. 2000. Apparent de-
Parris, L. B., M. M. Lamont, and R. R. Carthy. cline ofthe southern hog-nosed snake, Heterodon
2002. Increased incidence ofred imported fire ant simus.JournaloftheElishaMitchell ScientificSo-
(Hymenoptera; Formicidae) presence in logger- ciety 116:19-40.
head seaturtle (Testudines: Cheloniidae)nestsand WojciK, D. P, C. R. Allen, R. J. Brenner, E. A. For-
observations of hatchling mortality. Florida En- YS, D. P. JouvENAZ, AND R. S. LuTZ. 2001. Im-
tomologist 85:514-517. ported fire ants: impact on biodiversity. American
Pedersen, E. K., T. L. Bedford, W. E. Grant, S. B. Entomologist 47:16-23.