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THE WILSON JOURNAL OF ORNITHOLOGY • Vol. 124. No. 2. June 2012 
buffers. The only difference we observed was that 
birds nesting in buffer habitat brought slightly 
more Orthoptera (2008) than those nesting in non¬ 
buffer habitats. Foraging distances did not differ 
between buffer and non-buffer sites, suggesting 
birds had relatively equivalent foraging resources 
and opportunities around the nest. Thus, in terms 
of nestling provisioning, any difference in habitat 
quality was not large, and native grass conserva¬ 
tion buffers in the CRP may represent additional 
primary habitat. 
Observer Effects on Provisioning .—Dickcissels 
made — 10% fewer feeding visits, brought pro¬ 
portionately fewer orlhopterans (2008), and nest¬ 
lings received -14% less biomass when observ¬ 
ers were present. Our results are of concern 
because human presence was low (I observer) and 
was not near the nest (~30 m distant). Observers 
were careful to minimize disturbance (i.e., no loud 
noises or sudden behaviors), and human presence 
was not novel because technicians conducting 
nest searching and monitoring were present prior 
to filming. In contrast, using a ladder for 
observations may have potentially increased 
threats perceived by Dickcissels because it 
mimicked vertical perches used by visual preda¬ 
tors (Andersson et al. 2009). Our observer 
presence would be qualitatively similar to or less 
intrusive than many farming activities occurring 
in agricultural landscapes (e.g.. herbicide appli¬ 
cation. mowing, harvesting, checking fields) that 
would pul humans and/or machinery in or near 
bulfer habitats. Our levels of presence are 
qualitatively similar to many recreational activi¬ 
ties (e.g.. wildlife-watching, hiking, etc.) that 
occur in both crop and non-crop habitats (e.g., 
more natural areas) in agricultural landscapes. 
Human disturbance has become more frequent 
in recent years as the exurban footprint expands 
into agricultural landscapes and more natural 
areas such as parks and refuges allow access to 
increasing numbers of recreationists and ecotour- 
ists (Cordell et al. 2008). 
Birds modify choices in foraging behavior and 
limit activity around the nest if threatened by 
predators, and humans may be perceived as 
predators (Dunn el al. 2010). Birds may thus 
choose to forage in habitats that are suboptimal 
(e.g., Fernandez-.!uricic and Tcllcria 2000) or 
reduce provisioning rates. Reduced nestling 
growth rate can be a direct result of chronic 
predator presence (Clinchy et al. 2004, Dunn et al. 
2010 ), which indirectly may increase time to 
fledging and prolong nestling exposure to preda¬ 
tion (Bize et al. 2003). Birds may also have 
chronic stress (elevated glucocorticostcroid lev¬ 
els) when food availability and predation ask act 
together (Clinchy et al. 2004. Eggers et al. 200X, 
Dunn et al. 2010) which may impact reproductive 
capacities (Zanette et al. 2003). Stressed females 
may pass elevated hormone levels to eggs with 
subsequent effects on offspring phenotype (Saino 
et al. 2005). Nestlings with poor body condition 
and slow growth rate may have lower social 
rankings as adults and continue to experience 
reduced body size and lifespan (Metcalfe and 
Monaghan 2001). 
Human presence may reduce foraging rates of 
adults (e.g.. Fernandez-Juricic and Telleria 2000). 
influence seasonal timing of song (Gut/.willer et 
al. 1997), and decrease survival rates of nestlings 
and fledglings (e.g., Safina and Burger 1983), We 
know of no documentation of decreased provi¬ 
sioning as a direct result of human presence for 
grassland birds other than our study. Seemingly 
benign human activities may have more substan¬ 
tial effects on breeding success than currently 
assumed if reduced provisioning is a common 
response to low levels of human intrusion. 
Remote monitoring of birds with video technol¬ 
ogy also may decrease potential for research- 
related effects on nesting birds compared to direct 
observation. 
Male Helping .—Male helping increased provi¬ 
sioning rates but biomass delivered was not 
different because males brought fewer Orthoptera 
(2008) and smaller prey items (2009) than 
females. The major benefit of mule helping 
appears to be decreased effort by the female 
rather than increased provisioning of the young 
(and hence greater survivorship). 
Several hypotheses may explain male helping 
First, males may be more likely to help when food 
abundance is low (e.g., Wittenberger I9S2) 
Rainfall during the breeding season increased 
almost two-fold in 2009 versus 2008 (May-Aug 
2008 rainfall - 222 mm: May-Aug 2009 rain¬ 
fall = 420 mm: Mississippi State Department i'i 
GeoScicnces). Vegetation density and subsequent 
invertebrate abundance are typically greater in 
wetter years, but males helped in both years- 
Sccond, males may have more incentive to help 
al late-season nests (Igl and Best 2001) as predation 
risk increases (daily survival rate of nests decreased 
as the breeding season progressed in our study: 
Adams 2011). However, we observ ed male helping 
