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Do hair-crested drongos reduce prospective territory competition by dismantling their nest after breeding?

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Animals that breed seasonally often use the same territory where they successfully produced young previously. Intra-specific competition may be intense for these high-quality territories, and therefore, natural selection should favour behaviour of territory owners to reduce such competition. Hair-crested drongos, Dicrurus hottentottus, a territory-faithful migratory passerine, dismantle their nests after breeding. As undismantled nests usually remain intact until the next breeding season, we hypothesised that nest dismantling serves the purpose of reducing territory competition from conspecifics that may use the presence of a nest as a cue to select suitable territories in the next year. Here, we provide the first experimental test of this “territory competition hypothesis”. Our results show that successful pairs, who often reuse their territories in the next year, were more likely to dismantle their nests and tended to dismantle faster compared to failed breeding pairs who often moved to another territory in the next year. Strengthened natural nests that were experimentally placed in successful territories attracted prospectors. However, the usurpation rate of those territories in the following year was low and not higher than that of territories where nests were dismantled. Furthermore, returned strengthened-nest owners did not initiate breeding later or produce fewer fledglings suggesting that potential higher territory competition did not affect their reproduction. Altogether, our results only partially support the “territory competition hypothesis”. We suggest that nest dismantling may only be beneficial to drongos in years when territory competition is very intense. Significance statement Seasonal-breeding animals may face intra-specific competition for high-quality territories. Successful individuals often reuse their territory, but whether they can reduce prospective territory competition through hiding breeding locations (e.g. nests) has rarely been studied. We conducted an experiment to test whether a medium-sized passerine reduces the potential costs of territory competition by destroying their nest after breeding, concealing their selection of territory to other individuals. Territory owners invested more in nest dismantling if they were more likely to reuse the territory. However, they were still able to retain their previous territory and did not have a lower reproductive success if their nest was not dismantled. We suggest that individuals may only benefit from masking public information of breeding habitat selection from conspecifics by dismantling their nest when territory competition is very intense.
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ORIGINAL ARTICLE
Do hair-crested drongos reduce prospective territory competition
by dismantling their nest after breeding?
Lei Lv
1,2,3
&Jianqiang Li
4
&Sjouke A. Kingma
2
&Chang Gao
1
&Yong Wang
1,5
&Jan Komdeur
2
&Zhengwang Zhang
1
Received: 28 September 2017 / Revised: 3 December 2017 /Accepted: 8 December 2017
#Springer-Verlag GmbH Germany, part of Springer Nature 2017
Abstract
Animals that breed seasonally often use the same territory where they successfully produced young previously. Intra-specific compe-
tition may be intense for these high-quality territories, and therefore, natural selection should favour behaviour of territory owners to
reduce such competition. Hair-crested drongos, Dicrurus hottentottus, a territory-faithful migratory passerine, dismantle their nests after
breeding. As undismantled nests usually remain intact until the next breeding season, we hypothesised that nest dismantling serves the
purpose of reducing territory competition from conspecifics that may use the presence of a nest as a cue to select suitable territories in
the next year. Here, we provide the first experimental test of this Bterritory competition hypothesis^. Our results show that successful
pairs, who often reuse their territories in the next year, were more likely to dismantle their nests and tended to dismantle faster compared
to failed breeding pairs who often moved to another territory in the next year. Strengthened natural nests that were experimentally
placed in successful territories attracted prospectors. However, the usurpation rate of those territories in the following year was low and
not higher than that of territories where nests were dismantled. Furthermore, returned strengthened-nest owners did not initiate breeding
later or produce fewer fledglings suggesting that potential higher territory competition did not affect their reproduction. Altogether, our
results only partially support the Bterritory competition hypothesis^. We suggest that nest dismantling may only be beneficial to
drongos in years when territory competition is very intense.
Significance statement
Seasonal-breeding animals may face intra-specific competition for high-quality territories. Successful individuals often reuse their
territory, but whether they can reduce prospective territory competition through hiding breeding locations (e.g. nests) has rarely been
studied. We conducted an experiment to test whether a medium-sized passerine reduces the potential costs of territory competition by
destroying their nest after breeding, concealing their selection of territory to other individuals. Territory owners invested more in nest
dismantlingiftheyweremorelikelytoreusethe territory. However, they were still able toretaintheirpreviousterritoryanddidnot
have a lower reproductive success if their nest was not dismantled. We suggest that individuals may only benefit from masking public
information of breeding habitat selection from conspecifics by dismantling their nest when territory competition is very intense.
Keywords Nest dismantling .Hair-crested drongos Dicrurus hottentottus .Territory competition .Adaptive behaviour .
Prospector
Communicated by J. A. Graves
*Jan Komdeur
j.komdeur@rug.nl
*Zhengwang Zhang
zzw@bnu.edu.cn
1
Ministry of Education Key Laboratory for Biodiversity and
Ecological Engineering, College of Life Sciences, Beijing Normal
University, Beijing, PeoplesRepublicofChina
2
Behavioural and Physiological Ecology, Groningen Institute for
Evolutionary Life Sciences, University of Groningen,
Groningen, The Netherlands
3
School of Life Sciences, Sun Yat-sen University,
Guangzhou, PeoplesRepublicofChina
4
College of Nature Conservation, Beijing Forestry University,
Beijing, PeoplesRepublicofChina
5
Department of Biological and Environmental Sciences, College of
Agriculture, Life, and Natural Sciences, Alabama A&M University,
Normal, AL, USA
Behavioral Ecology and Sociobiology (2018) 72:12
https://doi.org/10.1007/s00265-017-2422-1
Introduction
In many animals, individuals occupy the same territory
over consecutive years (Greenwood 1980;Switzer1993;
Newton 2008;Piper2011). This kind of territory fidelity
can benefit individuals because of experience with local
conditions (Beletsky and Orians 1991;Pärt1995). Such
experience consists of prior knowledge of local food re-
sources, predator habits or predator refuges and support
from familiar neighbours, which often leads to higher for-
aging efficiency, better breeding performance and higher
survival rates (Hinde 1956;Stamps1995; Grabowska-
Zhang et al. 2012). Furthermore, territory fidelity usually
follows good breeding performance in a particular territo-
ry (Gavin and Bollinger 1988; Switzer 1997; Haas 1998;
Robert and Paiva 2014), because breeding performance
provides an indirect assessment of territory quality when
habitat, predation or food conditions are temporally and
spatially predictable (Boulinier and Danchin 1997;
Doligez et al. 2003). Thus, the optimal strategy for ani-
mals is to remain faithful to the territory where their past
reproductive success was high (Nowak and Sigmund
1993; Switzer 1993;Schmidt2001).
Individuals that prefer to reuse a successful territory
may face territory competition from conspecifics, espe-
cially when potential competitors use the past breeding
performance of other pairs as a cue to assess the quality
of the territory. There is substantial evidence that prospec-
tors, which are immature individuals, failed breeders or
non-breeders, gather information on local patch quality
at the end of a breeding season to select the optimal ter-
ritory for the next season (reviewed in Reed et al. 1999;
Ponchon et al. 2013). Territory competition may impact
the fitness of individuals not only because they may lose
their preferred territory but also because of time loss, en-
ergy expenditures and risks of injury incurred during
fights (Eason and Hannon 1994;Marleretal.1995;
Cleveland 1999). Therefore, behavioural tactics to reduce
prospective territory competition are predicted to be
favoured by natural selection. Indeed, in common loons,
Gavia immer, where prospecting individuals use the pres-
ence of fledglings as a cue to locate good territories and
usurp it in the subsequent year (Piper et al. 2000,2006),
territory owners show a tendency to conceal chicks from
prospecting individuals, perhaps to avoid future territory
takeovers (Piper et al. 2006). Apart from chicks, the pres-
ence of a nest may also indicate the suitability of the
territory for breeding to conspecifics. In the Eurasian
penduline tit, Remiz pendulinus, males use old nests as a
cue to select suitable territories (Gergely et al. 2009), and
many cavity nesters prefer nest boxes containing old nests
over nest boxes without nests (Thompson and Neill 1991;
Davis et al. 1994; Mazgajski 2003,2007). Therefore, it
can be expected that, in species with high territory fidel-
ity, nest owners who reproduced successfully aim to mask
cues that signal suitable territories, in order to reduce ter-
ritory competition in the next year.
The hair-crested drongo, Dicrurus hottentottus,ami-
gratory insectivorous passerine, exhibits a nest-
dismantling behaviour in that most parents dismantle their
nests within two weeks after breeding (Li et al. 2009).
Apart from this species, this behaviour has only been ob-
served in two Indian laughing thrushes (Nilgiri laughing
thrush, Garrulax cachinnans, and white-breasted laughing
thrush, Garrulax jerdoni;Islam1989) and greater racket-
tailed drongos (Dicrurus paradiseus, LL, personal obser-
vations). Why birds dismantle their nest after breeding has
never been tested. In hair-crested drongos, nests are sol-
idly built (consisting of mainly fine grass stems and root-
lets) and, in combination with opportunity-costs, nest dis-
mantling is likely to be energetically costly. A previous
study proposed that nest dismantling may reduce the pos-
sibility that conspecifics are triggered by the presence of a
nest to compete for the territory in the following breeding
season (Bterritory competition hypothesis^;Lietal.
2009). This is likely because adult drongos show high
fidelity to their territories (Lv et al. 2016). Secondly, the
conspicuous nest of drongos is easy to locate and there-
foremaybeusedasacuebyprospectingindividualsin
searching for future territories. Thirdly, some non-
breeding yearlings obtained a territory in the subsequent
year nearby the territory where they had been ringed (LL,
unpubl. data). It indicated that yearlings were prospecting
at that moment, and prospecting occurs in the local area
which covers several nearby territories. Thus, by disman-
tling the nest, drongos may conceal their high-quality ter-
ritories from other individuals and avoid or reduce the
potential costs of territory competition and losing their
territory in the following year.
Here, we consider a number of predictions and assump-
tions of the Bterritory competition hypothesis^. First, we ex-
pected that nests remain intact until the next breeding season if
they were not dismantled. Second, we predicted that, if failed
breeders were less likely to reuse the territory in the following
year, they were less motivated to dismantle their nest than
successful individuals. Third, we prospected that experimen-
tally strengthened nests, which remained intact until the next
breeding season, should attract conspecifics to the territory
and lead to a higher usurpation rate of territories in the follow-
ing year. Finally, we predicted that strengthened nests placed
in successful territories should lead to reduced breeding per-
formance of owners in the following year due to the cost of
competition for retaining or even losing the previous territory.
By using observational and experimental data, this study pro-
vides the first experimental test of the Bterritory competition
hypothesis^.
12 Page 2 of 9 Behav Ecol Sociobiol (2018) 72:12
Materials and methods
Study site and study population
We conducted this study in a 400 ha area in the Dongzhai
National Nature Reserve (31.95° N, 114.25° E, elevation
100840 m) in central China (for more information on the
study site, see Li et al. 2009). The hair-crested drongo is a
socially monogamous passerine that forms long-term pair
bonds. Most of the birds that breed in China, including
in our study site, winter in Indochina (Rocamora and
Yeatma n - B e r t helot 2009). At our study site, drongos ar-
rive in late April and leave before mid-October (Gao et al.
2006). The data used in this study were collected between
2010 and 2016 with on average 77 (2010, 47; from 2011
to 2016, range 7586) breeding pairs monitored each
year, and almost 80% of the adults were ringed with a
unique set of colour rings. We caught individuals by
mist-netting in close proximity to the nest trees during
incubation or the nestling-provisioning period. None of
the caught individuals abandoned their nest after release.
Since our study involved focal animals in the field, it was
not possible to record data blind with respect to the hy-
potheses we tested.
Drongos are territorial during the breeding period, and
most of their territories are clustered in our study area
with each territory abutting at least one other territory.
Birds defend their territory vigorously from conspecific
intruders and raptors. They nest in larger hardwood trees
or Chinese water firs, Metasequoia glyptostroboides,in
our study area (Cantrell et al. 2016). The cup-shaped nest
is built firmly in a tree crotch (Du and Zhang 1985;
Fig. 1), which is located near the end of a branch in the
middle canopy of the tall tree with an average ± SE nest
height of 8.28 ± 0.55 m (n= 50; Cantrell et al. 2016). Both
parents participate in nest building, incubation and off-
spring feeding. Modal clutch size is four eggs (75.64%,
range 35, n= 275) and hatching success is high (92.8%,
Lv et al. 2016). The main reason for unsuccessful breed-
ing is nest predation by predators such as Eurasian jays,
Garrulus glandarius, and besra sparrow hawks, Accipiter
virgatus (LL, personal observation). Drongos are general-
ly single-brooded with ca. two thirds of all nests produc-
ing at least one fledgling. Only 18.3% of the breeding
pairs (n= 120) lay replacement clutches after their first
clutch failed (Lv et al. 2016).
Data collection and field procedures
We searched for nests by checking trees that had been
used previously and potential nesting sites in the forest.
After a nest was located, we determined the identity of the
nest owners either through observations with a telescope
or binoculars, or through video recording, where video
cameras (Sony HDR-160E, Sony HDR-260E or
Samsung F40) were placed 1030 m from the nest. To
determine the breeding stage (nest building, egg laying,
incubation and nestling) and the fate (successful or fail-
ure) of each nest, we checked the nest every two or three
days by mirroring over nests or climbing trees. During the
nest-dismantling period (started from the first check of
nest failure or after the young fledged), we took pictures
of the nest every two or three days to record the propor-
tion of remaining nest material.
To test whether the nests of drongos can remain intact
until the next breeding season under natural conditions, we
performed a nest intactness experiment. In July 2010, we
collected ten nests by cutting the nest branch from the base
after fledging of the young. We then placed these nests
individually at a site in the study area that consists of low
shrubs. Drongos usually occur in the canopy of the forest
and were rarely observed at the site where the experimental
nests were situated. We placed all nests in their natural
position with the base of the nest branch tied to shrub
branches of similar thickness. Nests were located 1 m
above the ground with a distance of 0.5 to 4 m from each
other. We photographed each nest after it was fixed and
checked its condition again at the beginning of the next
breeding season (middle May 2011).
To investigate whether territory reuse was affected by pre-
vious breeding performance, we determined the rate of re-
usage of successful territories (at least one young fledged)
and failed territories for which both male and female breeders
were identified. We defined an individual as reusing the same
territory if it built a nest in the same tree as in the previous year
or in a tree within 62 m of the former nest tree (the average
radius that was calculated based on the area of intensive use at
60% isopleth of five home ranges in 2009 with fixed kernel
methods (Worton 1989;Börgeretal.2006)). Some individ-
uals moved to the nest tree where the adjacent pair had bred in
the previous year, which was also less than 62 m from their
original nest tree; we defined those as having Bchanged
territory^.
To examine whether drongos dismantled their nest
according to breeding performance, we monitored the
nest dismantling of successful nests and failed nests.
As some breeding pairs produced replacement clutches
after their first breeding attempt failed and they might
dismantle their first nest to use nest material for build-
ing a new nest (LL, unpubl. data), failed nests of breed-
ing pairs who subsequently produced a replacement
clutch were not included in the analyses. We used pho-
tographs of the nest that were taken during nest checks
to define the stage of the nest dismantling. Four stages
were used according to how much of the nest material
was left (stage 4, 75%; stage 3, 5075%; etc.; Fig. 1).
Behav Ecol Sociobiol (2018) 72:12 Page 3 of 9 12
All nests were assessed by the same observer (LL). We
defined the duration of nest dismantling as the average
duration (in days) when more than 50% of the nest and
more than 75% of the nest were dismantled (i.e. from
dismantling onset to the first recording date of stage 2
and stage 1), respectively. From 2011 to 2014, drongos
were present until 912 October. Therefore, we defined
nests that still had more than one fourth of nest material
left in mid-October as not dismantled.
To test whether the existence of a nest in a territory affected
territory competition in the following year, we carried out a
nest-hanging experiment by using successful nests for which
both male and female breeders were identified from 2011 to
2013. Eighty-five nests were randomly assigned to a control
or an experimental group after the young fledged. Nests in the
experimental group (n= 38) were collected by cutting the nest
branch from the base and strengthened using a grey Dyneema
PE fishing line (line number, 8.0; diameter, 0.50 mm) to make
the nests indestructible for drongos (Fig. 2). All nests were
stitched densely in the same manner by the same experimenter
(CG). Within two days after the nests were collected, we re-
attached strengthened nests to a similar position and orienta-
tion of its original location by fixing the base of the nest
branch to a similar-sized branch with steel wire.
To test whether drongos accept experimentally strength-
ened nests and treat them as natural nests, we compared the
nest visitation rates of nest owners and conspecifics (e.g. pros-
pectors) between strengthened nests and natural nests in the
nest-dismantling period, respectively. In 2011, nine strength-
ened nests in the experimental group were monitored by
motion-triggered infrared cameras (Scoutguard SG550), each
set about 0.4 m from the strengthened nest. We set cameras to
the video mode with 0 s interval after each trigger. Video
length was set to 60 s. Only the recordings for which nests
had been monitored for the entire day (5:30 to 19:30) in the
first month of monitoring were used in the analysis. On aver-
age, each nest was monitored 8.67 ± 1.00 days (mean ± SE,
n= 9). We also recorded the nest visits of ten natural nests that
succeeded in producing fledglings through filming in the nest-
dismantling period (from the dismantling onset until at least
one fourth of nest material was left). Each nest was monitored
on average ± SE: 48.90 ± 33.55 h (n= 10). All owners of nests
that were monitored by infrared cameras or video cameras
were individually ringed with a unique combination of colour
rings. Nest owners and conspecifics visited the strengthened
nests and natural nests, and there was no significant difference
in visitation rates between these two types of nests, despite an
apparent trend (nest visitation rates of parents: strengthened
nests = 0.07 ± 0.11 times/h (mean ± SE), natural nests = 0.16
± 0.19 times/h (mean ± SE), t=1.30,p=0.212;nestvisitation
rates of conspecifics: strengthened nests = 0.10 ± 0.12 times/h
(mean ± SE), natural nests = 0.18 ± 0.18 times/h (mean ± SE),
t= 1.22, p= 0.238; n
strengthened nests
=9, n
natural nests
=10).
Therefore, we assume that drongos treated strengthened nests
as natural nests.
In the nest-hanging experiment, all nests in the control
group, but none in the experimental group (all nests were
complete), were dismantled by drongos in 9.82 ± 1.69 days
(mean ± SE, n= 39). Thus, nests in the experimental group
did persist longer (about 3 months from early July till the
migration time in September and October) and consequently
attracted conspecifics for a much longer period than nests in
the control group. Therefore, it was legitimate to predict that
experimental territories experienced a higher territory compe-
tition in the following year than territories in the control group.
Fig. 2 A natural nest of hair-crested drongo strengthened with fishing line
Fig. 1 An overview of hair-crested drongo nest-dismantling stages: astage 4, full nest; bstage 2, between 25 and 50% of nest material left; cstage 1, less
than 25% of nest material left
12 Page 4 of 9 Behav Ecol Sociobiol (2018) 72:12
To test this prediction, we measured the territory competition
by checking the occurrence of territory usurpation in the ex-
perimental group and control group. We considered that the
territory was usurped if both territory owners in the next year
were new breeders and the former territory owner(s) survived
(whether the bird was resighted in our study area in any given
year during the next 3-year period). Given that the resighting
probability of birds breeding in our study area is very high
(0.941, n= 795; LL, unpubl. data), a missing bird can be reli-
ably considered as having died. No strengthened nests were
used by breeders, and they were removed at the end of the
breeding season (August) in the following year.
Statistical analyses
We tested whether the return rate and the territory reusing
rate of territory owners were influenced by their breeding
performance in the previous year. Furthermore, we also
explored whether the nests being dismantled (less than
25% of nest material left) or not (more than 25% of nest
material left) was related to reproductive success (yes or
no). For nests which were dismantled, we compared the
speed of dismantlement (in number of days) between suc-
cessful and failed nests. Additionally, we tested whether
prospecting events were influenced by the timing of
breeding and breeding performance by fitting a general
linear model (LM). The nest visitation rate of conspecifics
during the dismantling period (number of visits per hour)
was used as a response variable, and laying date and
number of fledglings (range from 1 to 4) were used as
predictors.
To investigate whether territories were more likely to
be usurped when nests were experimentally caused to
persist in the territory, we fitted Byear^,Btreatment^(ex-
perimental versus control) and Bnumber of fledglings pro-
duced in the previous year^as explanatory variables in a
generalised linear model (GLM) with binomial error and
logit link function. BUsurped or not^was set as binomial
response variables. By using the same model structure, we
also analysed the influence of the nest hanging experi-
ment on reproductive success of females and males, re-
spectively. Number of fledglings was used as an index for
reproductive success with low reproductive success de-
fined as producing none or one fledgling and high repro-
ductive success defined as producing two to five fledg-
lings (grouping into 0 and 15 gave the same result),
because the number of fledglings was distributed more
like in U shape (model clutch size is four, around one
third of all nests were predated and few nests were par-
tially predated). We used Akaikes information criterion
corrected for small sample size (AICc) to determine the
combination of variables that best explained the data with
minimal parameters (Burnham and Anderson 2002).
Model selection was performed by backward stepwise
elimination, and the fit of each new model was assessed
by comparison of AICc values. Model parameters were
dropped, except for Btreatment^or Bnumber of fledglings
produced in the previous year^, if doing so resulted in a
lower AICc score, which were obtained by using the
BAICcmodavg^package (Mazerolle 2011). Two two-way
interactions between Byear^and Btreatment^and between
Btreatment^and Bnumber of fledglings produced in the
previous year^were tested in all analyses, but were not
significant and therefore not reported.
The effect of the nest-hanging experiment on the timing of
breeding of females and males, respectively, was analysed by
fitting general linear models, using the laying date of the
breeding pair as the response variable. BTreatment^was used
as a predictor and laying date in the previous year was used as
acovariate.
The laying date of each nest was standardised by
subtracting the date of the first egg laid in any given year.
Only the laying date of the first breeding attempt in that season
was used. Standardised laying dates were log transformed to
meet the assumption of normality of the model residuals.
All analyses were conducted in either SPSS 19.0 (SPSS
Inc., Chicago, IL, USA) or R.3.1.1 (R Core Team 2012)pack-
age Blme4^(Bates et al. 2014). All tests were given two-tailed
and significance was assessed at p=0.05.
Data availability statement The datasets generated during
and/or analysed during the current study are available in the
figshare repository, https://figshare.com/articles/Nest-
dismantling/5611303.
Results
Nest intactness experiment
Nests that were removed and stored elsewhere were still intact
in eight of ten cases in the following breeding season. It indi-
cated that most nests survived until the next year if they were
not dismantled by drongos. For the two incomplete nests, the
nest material dropped from the branches and nothing was left.
Return rate, territory reusing rate and nest
dismantling
There was no difference in the probability that successful
males or failed males returned to the study area in the next
year (chi-square test, χ
2
=0.06, p= 0.812; Fig. 3), but fewer
females returned if they failed in the previous year (chi-square
test, χ
2
= 5.57, p= 0.018; Fig. 3). Both males and females
were less likely to reuse the territories if they failed in the
previous year (chi-square test, both p<0.007; Fig. 3). Nine
Behav Ecol Sociobiol (2018) 72:12 Page 5 of 9 12
of the 83 failed nests (10.8%) and five of the 187 successful
nests (2.7%) were not dismantled, indicating that failed nests
were significantly less likely to be dismantled than successful
nests (chi-square test, χ
2
=7.80,p= 0.005). Furthermore, nest
dismantling of failed nests took on average 2.97 days longer
than that of successful nests (failed nested = 12.61 ± 1.35 days
(mean ± SE, n= 67), successful nests = 9.64 ± 0.70 days
(mean ± SE, n=174), t=1.96,p=0.053).
Nest-hanging experiment
The nest visitation rate of conspecifics was not affected by the
laying date nor by the number of fledglings (LMs: laying date,
F
19
=0.47, p=0.501, ΔAICc = + 2.33; number of fledglings,
F
19
=0.68, p=0.582, ΔAICc = + 8.83; r
2
full model
=0.12).
Furthermore, the usurpation rate of territories was not affected
by whether the territory contained a strengthened nest or not
(GLM with binomial error: z
74
=0.40,p=0.686)orthenum-
ber of fledglings produced in the previous year (GLM with
binomial error: z
74
=0.75, p=0.453, r
2
final model
= 0.03).
Furthermore, laying date (LMs: females: t
38
=1.34, p=
0.189, r
2
final model
= 0.16; males: t
46
=0.65, p=0.522, r
2
final
model
= 0.11) and reproductive success of returned nest owners
(GLMs with binomial error: females: z
38
=0.54, p=0.590,
r
2
final model
= 0.09; males: z
47
=0.21, p=0.830,r
2
final model
=
0.35) were also not significantly influenced by the nest-
hanging treatment.
Discussion
Our results show that most drongo nests were still intact at the
beginning of the next breeding season if they had not been
dismantled. Therefore, they have the potential to serve as cues
of suitable territories to other individuals. Consistent with the
prediction of the Bterritory competition hypothesis^(Li et al.
2009), we found that successful breeders were more likely to
dismantle their nests and tended to dismantle faster than failed
breeders as the territory reusing rate was higher after success-
ful breeding attempts. Although nests that were experimental-
ly strengthened so they persisted until the next breeding sea-
son attracted prospectors, the usurpation rate of territories in
the following breeding season was not affected by this exper-
imental treatment. Furthermore, nest owners did not initiate
breeding later or produce fewer fledglings due to the poten-
tially higher territory competition after this treatment. Thus,
our results only partially support the prediction that nest dis-
mantling is an adaptive behaviour for drongos to reduce terri-
tory competition from conspecifics in the following breeding
season.
The effect of breeding dispersal on nest dismantling
Drongos that failed to produce fledglings in the previous year
were more likely to change their territory than individuals that
had succeeded (Fig. 3), a finding that echoes what others have
reported (Alcock 1993; Switzer 1993; Haas 1998; Apollonio
et al. 2003;Hoover2003). Therefore, if individuals benefit
from nest dismantling in terms of reduced territory competi-
tion in the following year, failed breeding pairs that were more
likely to disperse should be less motivated to dismantle their
nest. Furthermore, there is substantial evidence in other spe-
cies that individuals, who failed in their own breeding, pros-
pect the breeding performance of others to locate the high-
quality territories where they preferentially settle to breed in
the following year (Eadie and Gauthier 1985;Cadiouetal.
1994; Doligez et al. 2004; Ward 2005;Calabuigetal.2010;
Schuett et al. 2012). In drongos, nests were visited nearly
always by conspecifics during the dismantling period (rarely
in other periods; each year in total only one or two conspe-
cifics were observed during the period when the breeding pair
was actively attending the nest (either during nest building,
incubation or nestling-provisioning period; at least 40 nests in
each stage)), which suggests that prospecting occurred. Failed
Fig. 3 Return rate and territory
reusing rate of hair-crested dron-
go territories after a pair was a
successful (n=109) orbfailed to
produce fledglings (n= 27) in the
previous year. Individuals who
did not return most likely died
12 Page 6 of 9 Behav Ecol Sociobiol (2018) 72:12
drongos may gain an adaptive benefit by prospecting rather
than dismantling their nests. This may explain the lower oc-
currence and low speed of nest dismantling in failed breeders.
Nest dismantling and prospective territory
competition
In agreement with the Bterritory competition hypothesis^,our
experimental presentation of strengthened nests revealed that
these indeed attract prospectors. As the prospecting frequency
of conspecifics was not affected by the laying date nor by the
number of fledglings produced in the prospected territory,
territories with strengthened nests should experience a higher
territory competition in the following year than territories in
the control group due to the longer period of attracting con-
specifics in a similar prospecting frequency. However, the
experiment did not demonstrate a higher usurpation rate of
strengthened nest territories in the next year. When prospec-
tors competed for territories that were selected based on the
assessment of the previous year, prior residency of territory
owners often confers an advantage in maintaining the owner-
ship of a territory regardless of who occupies it first. If pros-
pectors compete with individuals who already retained their
previous territories, it has been reported that residents consis-
tently dominate opponents in aggressive interactions within
their familiar areas (the Bresident advantage^; reviewed by
Kokko et al. 2006). Besides, even if prospectors had occupied
the territory before the owners from the previous year arrived,
most of them were subsequently evicted when the owners
from the previous year returned (Nolan 1978; Jakobsson
1988; but see Arcese 1987). For instance, a study on the
northern wheatear, Oenanthe oenanthe, revealed that individ-
uals selected the territories that they had prospected in the
previous year, but the probability of successfully acquiring
these territories was strongly dependent on the survival of
the original owners (Pärt et al. 2011). In our study population,
we also observed that settled new breeding pairs were re-
placed by pairs consisting of at least one bird from the previ-
ous year during the nest-building period (LL, unpubl. data).
Therefore, the advantage of the original territory owners in
retaining territories may have led to the relatively low usurpa-
tion rates of territories in both of the experimental and control
groups, and the small difference between these two groups. As
a consequence, prospectors may not benefit from prospecting
in terms of getting access to high-quality territories. In fact,
only 7 out of 74 (9.5%) territories in the experimental and
control groups together were usurped by new birds in the next
year (4 of 7 using the same nest tree and the other 3 nested in
trees 11, 17 and 43 m away from the original nest tree, respec-
tively). Most of former owners, who moved, bred near their
old territories. This result suggests that territory competition
did exist in our study population during the study period, but
the intensity may be too weak to motivate drongos to reduce
the prospective cost of territory competition by dismantling
their nest.
If former territory owners do not return (most likely died),
strengthened nests may attract prospectors and lead to a higher
occupation rate of territories. However, although the sample
size was small due to limited mortality, territories with an
experimental nest were not occupied more often than terri-
tories without strengthened nests (33.3%, 1 of 3 versus
25.0%, 2 of 8 territories, respectively). To properly investigate
whether the presence of used nests attracts drongos, one
should position used nests in suitable areas without drongos
present and subsequently monitor whether this results in a
higher probability of drongos occupying these areas compared
to empty suitable areas without experimental nests. Our result
indicates that unoccupied high-quality territories existed in the
breeding area, and the low occupation rate (only 3 of 11 terri-
tories) may mean that territory competition is relatively low in
the population. Furthermore, both the timing of breeding and
reproductive success of territory owners were not influenced
by the strengthened nest placed in their territory in the previ-
ous year, which suggested that potential territory competition
induced by the presence of a (strengthened) nest did not lead
to reduced breeding performance in drongos. Therefore, we
suggest that there would be no or little conceivable costs for
drongos if they would not dismantle their nest under condi-
tions of weak territory competition.
Competition may be higher in high-quality territories. We
have indications that territory quality varies across the study
area: in 25 territories (31.2%, 25/80), breeding pairs consis-
tently succeeded in producing fledglings in at least 4 years
during our study period (more than half of our study period).
Although this success may be attributed to territory owners
being more experienced, it may also reflect differences in
territory quality. In contrast, territories that failed to produce
fledglings in one or two breeding seasons were usually not
occupied anymore afterwards (Fig. 3). We quantified the fre-
quency of prospecting visits for some 25 territories and found
that the prospecting visits were not more common in high-
quality territories (high-quality territories = 0.10 ± 0.09 times/
h(mean±SE,n= 5), low-quality territories = 0.21 ± 0.22
times/h (mean ± SE, n= 14), t=1.08, p= 0.296; LL,
unpubl. data). However, this analysis was based on limited
sample size, inhibiting to find a statistical difference; future
work on testing the effect of territory quality on territory com-
petition may provide valuable insights into whether nest dis-
mantling is shaped by territory competition.
Conclusion
Altogether, our results only partially support the Bterritory
competition hypothesis^that drongos dismantle their nests
to reduce territory competition in the following breeding
Behav Ecol Sociobiol (2018) 72:12 Page 7 of 9 12
season. Territory owners that succeeded in producing fledg-
lings were more likely to dismantle nests and tended to dis-
mantle them faster because they were more often reusing the
territories in the following year. Prospectors may use the in-
formation about nest locations in selecting preferred territories
for the following breeding season. However, due to the advan-
tage of original territory owners in retaining their territory, few
prospectors may be able to usurp territories. Furthermore,
owners did not seem to suffer from territory competition in
terms of breeding performance. One potential alternative ex-
planation is that nest dismantling may benefit drongos only
when territory competition is very intense in the population, a
hypothesis that remains to be tested. However, the exact func-
tion of nest dismantling needs further study.
Acknowledgements We are grateful to Luis Biancucci, Peng Zhang,
Zheng Chen, Matt Lerow, Matthew Slaymaker, Andrew Cantrell, Xu
Luo, Hang Zhang, Etienne Melese, Samuel S. Snow, Gabriele
Cavallini, Constance Fastré, Yifeng Zhong, Zhi Zheng, Sebastian Orue
and Elsa D. Lake who helped with the fieldwork and Dongzhai National
Reserve for the permission and assistance to the work. We thank three
anonymous reviewers for their comments on previous versions of this
manuscript.
Funding ZZ was supported by the National Key Programme of Research
and Development, Ministry of Science and Technology (2016YFC0503200),
and the B985 Project^of Beijing Normal University; JL by National Natural
Science Foundation of China (No. 31101644; 31472011); JK by the
Netherlands Organisation for Scientific Research (NWO: VICI grant
865.03.003, and ALW grant 823.01.014); and SAK by NWO (VENI grant
863.13.017).
Compliance with ethical standards
Conflict of interest The authors declare that they have no conflict of
interest.
Ethical statement This study abided by the Law of the Peoples
Republic of China on the Protection of Wildlife (27 August 2009) and
was approved by the Administration Bureau of Dongzhai National Nature
Reserve. The banding of birds was licensed by the National Bird Banding
Centre of China (No. 20090003). During the study period, we did not
observe any fledglings returning to the nest for resting. Therefore,
collecting nests after the young fledged have not influenced the survival
rate of fledglings. As drongos occasionally reuse the same branch in the
next year and there are many similar branches on the nest tree, we pre-
sume that cutting one nest branch has no or little influence on the subse-
quent breeding activity.
References
Alcock J (1993) Differences in site fidelity among territorial males of the
carpenter bee Xylocopa varipuncta (Hymenoptera: Anthophoridae).
Behaviour 125(3):199217. https://doi.org/10.1163/
156853993X00245
Apollonio M, Scotti M, Gosling LM (2003) Mating success and fidelity
to territories in a fallow deer lek: a female removal experiment.
Naturwissenschaften 90(12):553557. https://doi.org/10.1007/
s00114-003-0475-7
Arcese P (1987) Age, intrusion pressure and defence against floaters by
territorial male song sparrows. Anim Behav 35(3):773784. https://
doi.org/10.1016/S0003-3472(87)80114-8
Bates D, Maechler M, Bolker B (2014) Package Blme4^: linear mixed-
effects models using Eigen and S4. R package version 1:17https://
CRAN.R-project.org/package=lme4
Beletsky LD, Orians GH (1991) Effects of breeding experience and fa-
miliarity on site fidelity in female red-winged blackbirds. Ecology
72(3):787796. https://doi.org/10.2307/1940581
Börger L, Franconi N, De Michele G, Gantz A, Meschi F, Manica A,
Lovari S, Coulson T (2006) Effects of sampling regime on the mean
and variance of home range size estimates. J Anim Ecol 75(6):1393
1405. https://doi.org/10.1111/j.1365-2656.2006.01164.x
Boulinier T, Danchin E (1997) The use of conspecific reproductive suc-
cess for breeding patch selection in terrestrial migratory species.
Evol Ecol 11(5):505517. https://doi.org/10.1007/s10682-997-
1507-0
Burnham KP, Anderson DR (2002) Model selection and multimodel
inference: a practical information-theoretic approach. Springer
Science & Business Media, New York
Cadiou B, Monnat JY, Danchin E (1994) Prospecting in the kittiwake,
Rissa tridactyla: different behavioural patterns and the role of squat-
ting in recruitment. Anim Behav 47(4):847856. https://doi.org/10.
1006/anbe.1994.1116
Calabuig G, Ortego J, Aparicio JM, Cordero PJ (2010)Intercolony move-
ments and prospecting behaviour in the colonial lesser kestrel. Anim
Behav 79(4):811817. https://doi.org/10.1016/j.anbehav.2009.12.
007
Cantrell A, Lv L, Wang Y, Li J, Zhang Z (2016) Evaluation of nest site
preferences of a nest dismantler, the hair-crested drongo (Dicrurus
hottentottus) in Dongzhai national nature reserve of central China.
Avian Res 7:17
Cleveland A (1999) Energetic costs of agonistic behavior in two herbiv-
orous damselfishes (Stegastes). Copeia 1999(4):857867. https://
doi.org/10.2307/1447962
Davis WH, Kalisz PJ, Wells RJ (1994) Eastern Bluebirds prefer boxes
containing old nests. J Field Ornithol 65:250253
Doligez B, Cadet C, Danchin E, Boulinier T (2003) When to use public
information for breeding habitat selection? The role of environmen-
tal predictability and density dependence. Anim Behav 66(5):973
988. https://doi.org/10.1006/anbe.2002.2270
Doligez B, Pärt T, Danchin E (2004) Prospecting in the collared flycatch-
er: gathering public information for breeding habitat selection?
Anim Behav 297:457466
Du J, Zhang J (1985) Ecology observation on the summer ecology of the
hair-crested drongo Dicrurus hottentottus. Sichuan J Zool 4:2021
Eadie JM, Gauthier G (1985) Prospecting for nest sites by cavity-nesting
ducks of the genus Bucephala. Condor 87:528534
Eason P, Hannon SJ (1994) New birds on the block: new neighbors
increase defensive costs for territorial male willow ptarmigan.
Behav Ecol Sociobiol 34(6):419426. https://doi.org/10.1007/
BF00167333
Gao Z, Du Z, Wang X, Huang H, Wang K, Yang C (2006) The nest-site
selection of hair-crested drongo at Dongzhai Nature Reserve.
Chinese J Zool 41:6973
Gavin T, Bollinger E (1988) Reproductive correlates of breeding-site
fidelity in bobolinks (Dolichonyx oryzivorus). Ecology 69(1):96
103. https://doi.org/10.2307/1943164
Gergely Z, Mészáros LA, Szabad J, Székely T (2009) Old nests are cues
for suitable breeding sites in the Eurasian penduline tit Remiz
pendulinus.JAvianBiol40(1):26. https://doi.org/10.1111/j.1600-
048X.2008.04582.x
Grabowska-Zhang AM, Sheldon BC, Hinde CA (2012) Long-term famil-
iarity promotes joining in neighbour nest defence. Biol Lett 8(4):
544546. https://doi.org/10.1098/rsbl.2012.0183
12 Page 8 of 9 Behav Ecol Sociobiol (2018) 72:12
Greenwood PJ (1980) Mating systems, philopatry and dispersal in birds
and mammals. Anim Behav 28(4):11401162. https://doi.org/10.
1016/S0003-3472(80)80103-5
Haas C (1998) Effects of prior nesting success on site fidelity and breed-
ing dispersal: an experimental approach. Auk 115(4):929936.
https://doi.org/10.2307/4089511
Hinde R (1956) The biological significance of the territories of birds. Ibis
98:340369
Hoover JP (2003) Decision rules for site fidelity in a migratory bird, the
prothonotary warbler. Ecology 84(2):416430. https://doi.org/10.
1890/0012-9658(2003)084[0416:DRFSFI]2.0.CO;2
Islam MA (1989) Nest destruction and cannibalistic behaviour of
laughing thrushes, Garrulax spp. (Aves: Muscicapidae).
Bangladesh J Zool 17:1517
Jakobsson S (1988) Territorial fidelity of willow warbler (Phylloscopus
trochilus) males and success in competition over territories. Behav
Ecol Sociobiol 22(2):7984. https://doi.org/10.1007/BF00303541
Kokko H, Lopez-Sepulcre A, Morrell L (2006) From hawks and doves to
self-consistent games of territorial behavior. Am Nat 167(6):901
912. https://doi.org/10.1086/504604
Li J, Lin S, Wang Y, Zhang Z (2009) Nest-dismantling behavior of the
hair-crested drongo in central China: an adaptive behavior for in-
creasing fitness? Condor 111(1):197201. https://doi.org/10.1525/
cond.2009.080051
Lv L, Komdeur J, Li J, Scheiber IBR, Zhang Z (2016) Breeding experi-
ence, but not mate retention, determines the breeding performance in
a passerine bird. Behav Ecol 27(4):12551262. https://doi.org/10.
1093/beheco/arw046
Marler CA, Walsberg G, Moore MLW (1995) Increased energy expendi-
ture due to increased territorial defense in male lizards after pheno-
typic manipulation. Behav Ecol Sociobiol 37(4):225231. https://
doi.org/10.1007/BF00177401
Mazerolle MJ (2011) AICcmodavg: model selection and multimodel in-
ference based on (Q) AIC (c). R Package version 1:16 https://
CRAN.R-project.org/package=AICcmodavg
Mazgajski TD (2003) Nest site choice in relation to the presence of old
nests and cavity depth in the starling Sturnus vulgaris. Ethol Ecol
Evol 15(3):273281. https://doi.org/10.1080/08927014.2003.
9522672
Mazgajski TD (2007) Effect of old nest material on nest site selection and
breeding parameters in secondary hole nestersa review. Acta
Ornithol 42(1):114. https://doi.org/10.3161/068.042.0107
Newton I (2008) Migration ecology of birds. Academic Press, London
Nolan V (1978) The ecology and behavior of the prairie warbler
Dendroica discolor. Ornithological Monographs 26, American
OrnithologistsUnion, Washington
Nowak M, Sigmund K (1993) A strategy of win-stay, lose-shift that
outperforms tit-for-tat in the prisoners dilemma game. Nature
364(6432):5658. https://doi.org/10.1038/364056a0
Pärt T (1995) The importance of local familiarity and search costs for age-
and sex-biased philopatry in the collared flycatcher. Anim Behav
49(4):10291038. https://doi.org/10.1006/anbe.1995.0132
Pärt T, Arlt D, Doligez B, Low M, Qvarnström A (2011)
Prospectors combine social and environmental information
to improve habitat selection and breeding success in the sub-
sequent year. J Anim Ecol 80(6):12271235. https://doi.org/
10.1111/j.1365-2656.2011.01854.x
Piper WH (2011) Making habitat selection more Bfamiliar^: a review.
Behav Ecol Sociobiol 65(7):13291351. https://doi.org/10.1007/
s00265-011-1195-1
Piper WH, Tischler KB, Klich M (2000) Territory acquisition in loons:
the importance of take-over. Anim Behav 59(2):385394. https://
doi.org/10.1006/anbe.1999.1295
Piper WH, Walcott C, Mager JN, Perala M, Tischler KB, Harrington E,
Turcotte AJ, Schwabenlander M, Banfield N (2006) Prospecting in a
solitary breeder: chick production elicits territorial intrusions in
common loons. Behav Ecol 17(6):881888. https://doi.org/10.
1093/beheco/arl021
Ponchon A, Grémillet D, Doligez B, Chambert T, Tveraa T, González-
Solís J, Boulinier T (2013) Tracking prospecting movements in-
volved in breeding habitat selection: insights, pitfalls and perspec-
tives. Methods Ecol Evol 4(2):143150. https://doi.org/10.1111/j.
2041-210x.2012.00259.x
R Core Team (2012) R: a language and environment for statistical com-
puting. R Foundation for Statistical Computing, Vienna, Austria,
http://www.cran. r-project.org
Reed JM, Boulinier T, Danchin E, Oring LW (1999) Informed dispersal:
prospecting by birds for breeding site. Curr Ornithol 15:189259
Robert A, Paiva V (2014) Nest fidelity is driven by multi-scale informa-
tion in a long-lived seabird. Proc R Soc B 281(1793):20141692.
https://doi.org/10.1098/rspb.2014.1692
Rocamora G, Yeatman-Berthelot D (2009) Family Dicruridae (drongos).
In: del Hoyo J, Elliot A, Christie DA (eds) Handbook of the birds of
the world, 14th edn. Lynx Edicions, Barcelona, pp 172271
Schmidt KA (2001) Site fidelity in habitats with contrasting levels of nest
predation and brood parasitism. Evol Ecol Res 3:633648
Schuett W, Laaksonen J, Laaksonen T (2012) Prospecting at conspecific
nests and exploration in a novel environment are associated with
reproductive success in the jackdaw. Behav Ecol Sociobiol 66(9):
13411350. https://doi.org/10.1007/s00265-012-1389-1
Stamps J (1995) Motor learning and the value of familiar space. Am Nat
146(1):4158. https://doi.org/10.1086/285786
Switzer PV (1993) Site fidelity in predictable and unpredictable habitats.
Evol Ecol 7(6):533555. https://doi.org/10.1007/BF01237820
Switzer PV (1997) Past reproductive success affects future habitat selec-
tion. Behav Ecol Sociobiol 40(5):307312. https://doi.org/10.1007/
s002650050346
Thompson CF, Neill AJ (1991) House wrens do not prefer clean
nestboxes. Anim Behav 42(6):10221024. https://doi.org/10.1016/
S0003-3472(05)80157-5
Ward MP (2005) Habitat selection by dispersing yellow-headed black-
birds: evidence of prospecting and the use of public information.
Oecologia 145(4):650657. https://doi.org/10.1007/s00442-005-
0179-0
Worton BJ (1989) Kernel methods for estimating the utilization distribu-
tion in home-range studies. Ecology 70(1):164168. https://doi.org/
10.2307/1938423
Behav Ecol Sociobiol (2018) 72:12 Page 9 of 9 12
... To test whether the trade-off between providing parental care and pursuing extra-pair matings of males is limited by the distance from the focal male's nest to the nest of extra-pair mates, we measured extra-pair mating opportunities at different distance-categories. The average radius of hair-crested drongo territories is 62.0 ± 8.8 meters (mean ± SE, N = 5 territories; Lv et al. 2018), which was calculated based on the area of 60% isopleth of home ranges with fixed kernel methods (Worton 1989;Börger et al. 2006). Since most nests were located in this study area (Lv et al. 2016), we could measure the extra-pair mating opportunities for each focal male by counting the number of fertile females nearby. ...
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