The Wilson Journal of Ornithology 124(2):298-309. 2012 
PROVISIONING OF NESTLING DICKCISSELS IN NATIVE 
WARM-SEASON GRASS FIELD BUFFERS 
KRISTINA L. MITCHELL,' SAMUEL K. RIFFELL. 1 - 3 
L. WES BURGER JR., 1 AND FRANCISCO J. VILELLA’ 
ABSTRACT. —We used video cameras in 2008-2009 to record provisioning activities at Dickcissel (Spiza americam 
nests in and around Conservation Reserve Program field buffers in north-central Mississippi. USA. We simultaneously 
observed foraging flight distances of parents. Provisioning rate (P = 0.412). biomass (P = 0.161). and foraging distance 
(P = 0.159) did not increase with nestling age. Parents delivered larger items to meet demand associated with older 
nestlings (P = 0.010-0.001). This suggests energetic costs of changes in prey selection Were less than costs of increasing 
the number or distance of provisioning trips. Presence of male helpers increased provisioning rate t P < 0 . 001 ) but not 
biomass (P = 0.992) because males brought smaller prey items (P = 0.001-0.021). Presence of observers 30 m from the 
nest reduced provisioning rates (P = 0.005) and biomass delivered (P - 0.066). Lack of habitat effects for any aspect of 
provisioning suggests grass field butlers provided nestling food resources similar to surrounding habitats. Use of continuous 
video monitoring of nest activity allows well-concealed activities including provisioning and male helping to be directly 
observed and better quantified. Received 7 September 2011. Accepted 26 January 2012. 
Nestling provisioning by birds can affect 
reproductive success. Short periods of decreased 
provisioning (either in rate or biomass) may cause 
slower growth, reduced body condition, decreased 
survivorship, and reduced fledging success of 
nestlings (Bryant and Westerterp 1983, Martin 
1987, Saino et al. 1997). Decreased provisioning 
can compromise future dominance ranks and 
lower probabilities of acquiring breeding territo¬ 
ries (Metcalfe and Monaghan 2001). Provisioning 
rates may also index available food and. conse¬ 
quently. habitat quality (e.g.. Brickie et al. 2000). 
Adults of most passerines feed 60-100% 
arthropods to nestlings to provide the proicin-rich 
diet necessary for rapid development. Parents can 
optimize net energetic gain per nest visit (foraging 
trip) by altering provisioning rates, load size 
(biomass), foraging distances, and prey taxa and 
sizes (Orians and Pearson 1979. Wright et al. 
1998). Provisioning nestlings is energetically 
costly tor parents and impacts parent survival 
(e.g., Dijkstra et al. 1990), size of future clutches, 
and intervals between broods and. ultimately, 
future reproductive potential (e.g., Dijkstra et al. 
1990, Decrenberg and Overkamp 1999). Thus, 
parents should prefer larger prey (especially for 
large clutches or older nestlings with greater 
Department of Wildlile. Fisheries and Aquaculture, 
Mississippi Slate University. Mississippi State, MS 39762 
USA. 
U.S. Geological Survey, Cooperative Research Unit, 
epartment ot Wildlife, Fisheries and Aquaculture. Mis¬ 
sissippi State University. Mississippi State, MS 39762 
USA. 
’Corresponding author; e-mail; sriffell@cfr.msstate.edu 
demand anil wider gapes) that reduce searching 
time and provide more energy per provisioning 
trip (Wright et al. 1998, Britschgi et al. 20061, 
Parents should minimize search time by foraging 
close to the nest, and only forage at greater 
distances from the nest when food near the nest 
becomes difficult to find (Andersson 1981. 
Brickie et al. 2000, Britschgi et al. 2006) or when 
higher quality food sources are available at greater 
distances. 
Studying provisioning rates in grassland birds is 
important because they are experiencing large 
declines in the United States (1966-2009) com¬ 
pared to other bird guilds (Brennan and Kuvlesky 
2005. Sauer et al. 2011). Agricultural intensifica¬ 
tion. grassland habitat loss and fragmentation, and 
increased woody growth in remaining grasslands 
favoring forest-edge fauna have likely led to these 
declines of many grassland birds, especially in 
the Midwest and Great Plains (e.g., Samson and 
Knopf 1994. Brennan and Kuvlesky 2005). The 
U.S. Department of Agriculture's Conservation 
Reserve Program (CRP) since initiation in 198? 
has added millions of hectares of grassland habitat 
to agricultural landscapes in the United States u 
the form of whole field plantings and a variety ot 
buffer strip practices. Ostensibly, this program has 
benefited grassland bird populations (e.g., Ryan :l 
al. 1998. Herkeri 2009). However, little is known 
about provisioning rates, food availability (McIn¬ 
tyre and Thompson 2003), and habitat quality 
(reviewed by Haufler 2005) of CRP grasslands, 
especially in the southeastern USA (e.g.. Smi* 
et al. 2005) where grassland practices are lc s - 
common choices for CRP than in other regions. 
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