Perturbaciones antropogénicas y depredación en nidos artificiales en el suelo en un gradiente urbano En nuestro estudio con nidos artificiales observamos que la ausencia de  especies de aves que nidifican en el suelo en el centro urbano y en  barrios residenciales se debía a las molestias causadas por personas y  animales domésticos (perros y gatos) y no a la depredación. Además, la  presión por depredación fue superior en la periferia de la ciudad debido  al mayor número de depredadores naturales. Nuestros resultados sugieren  que la planificación y creación de zonas protegidas podrían aumentar la  posibilidad de que las aves que nidifican en el suelo se establecieran y  se reprodujeran en paisajes dominados por los humanos.Perturbaciones antropogénicas y depredación en nidos artificiales en el suelo en un gradiente urbano En nuestro estudio con nidos artificiales observamos que la ausencia de  especies de aves que nidifican en el suelo en el centro urbano y en  barrios residenciales se debía a las molestias causadas por personas y  animales domésticos (perros y gatos) y no a la depredación. Además, la  presión por depredación fue superior en la periferia de la ciudad debido  al mayor número de depredadores naturales. Nuestros resultados sugieren  que la planificación y creación de zonas protegidas podrían aumentar la  posibilidad de que las aves que nidifican en el suelo se establecieran y  se reprodujeran en paisajes dominados por los humanos.In our study with artificial nests we observed that the absence of  ground nesting bird species in the city centre and in residential  districts was due to disturbance by humans and domestic animals (dogs  and cats) rather than to predation. Furthermore, predation pressure was  higher in the outskirts of the city due to the greater number of natural  predators. Our results suggest that planning and creating undisturbed  areas could increase the chances of ground nesting birds settling and  breeding in human–dominated landscapes

Bocz, R.

Kurucz, K.

Purger, J. J.

Ronczyk, L.

Szép, D.

Witz, D.

Revistes Catalanes amb Accés Obert

153Animal Biodiversity and Conservation 40.2 (2017)
© 2017 Museu de Ciències Naturals de BarcelonaISSN: 1578–665 X
eISSN: 2014–928 X
Bocz, R., Szép, D., Witz, D., Ronczyk, L., Kurucz, K. & Purger, J. J., 2017. �uman distur�ances and preda�
tion on artificial ground nests across an ur�an gradient. Animal Biodiversity and Conservation, 40.2: 153–157.
Abstract 
Human disturbances and predation on artificial ground nests across an urban gradient.— In our study with 
artificial nests we o�served that  the a�sence of ground nesting �ird species in the city centre and in residential 
districts was due to distur�ance �y humans and domestic animals (dogs and cats) rather than to  predation. 
Furthermore, predation pressure was higher in the outskirts of the city due to the greater num�er of natural 
predators. Our results suggest that planning and creating undistur�ed areas could increase the chances of 
ground nesting �irds settling and �reeding in human–dominated landscapes.
Key words: Distur�ances, Nest survival, Plasticine eggs, Quail eggs, Ur�an development 
Resumen
Perturbaciones antropogénicas y depredación en nidos artificiales en el suelo en un gradiente urbano.— En 
nuestro estudio con nidos artificiales o�servamos que la ausencia de especies de aves que nidifican en el suelo 
en el centro ur�ano y en �arrios residenciales se de�ía a las molestias causadas por personas y animales 
domésticos (perros y gatos) y no a la depredación. Además, la presión por depredación fue superior en la 
periferia de la ciudad de�ido al mayor número de depredadores naturales. Nuestros resultados sugieren que 
la planificación y creación de zonas protegidas podrían aumentar la posi�ilidad de que las aves que nidifican 
en el suelo se esta�lecieran y se reprodujeran en paisajes dominados por los humanos.
Pala�ras clave: Pertur�aciones, Supervivencia en el nido, �uevos de plastilina, �uevos de codorniz, Desarrollo 
ur�ano 
Received: 31 VIII 16; Conditional acceptance: 13 X 16; Final acceptance: 9 I 17
R. Bocz, D. Szép, D. Witz, K. Kurucz & J. J. Purger, Dept. of Ecology, Inst. of Biology, Fac. of Sciences, Univ. 
of Pécs, 7624 Pécs, Hungary. – L. Ronczyk Dept. of Cartography and Geoinformatics, Inst. of Geography, Fac. 
of Sciences, Univ. of Pécs, 7624 Pécs, Ifjúság útja 6, Hungary.
Correspoding author: Jenő J. Purger. E–mail: purger@gamma.ttk.pte.hu
Human disturbances and predation 
on artificial ground nests 
across an urban gradient 
R. Bocz, D. Szép, D. Witz, L. Ronczyk, K. Kurucz 
& J. J. Purger
154 Bocz et al.
Introduction
Ur�anisation is a strong driver of �iodiversity loss 
�ecause most organisms show poor tolerance to 
environmental alterations (Sol et al., 2014). Ur�an 
�ird assem�lages are affected �y several mecha�
nisms, such as  nest predation (Jokimaki & �uhta, 
2000). Predator communities and nest predation 
vary across a gradient of increasing ur�anization, 
�ut relatively little is known a�out variation in pre�
dation pressure and factors affecting nest survival 
(Thorington & Bowman, 2003). Several artificial nest 
studies show that the rate of nest predation is higher 
in ur�an environments (e.g., Jokimäki & �uhta, 2000; 
Thorington & Bowman, 2003; Jokimäki et al., 2005) 
while  others  suggest that highly developed ur�an 
centres might provide a refuge from predation (Gering 
& Blair, 1999; Jokimäki et al., 2005). �igh densities of 
some 'ur�an adapter' �ird species could partly result 
from higher nesting success in cities, due to lower 
num�ers of specialist predators and/or lower impact 
of food–su�sidized generalist predators (Gering & 
Blair, 1999). According to Sol et al. (2014) the loss of 
species richness in ur�an ha�itats is  �etter explained 
�y adaptive differences among species rather than �y 
random processes. Most �irds living in the southern 
�ungarian city of Pécs �reed in �ushes, trees and 
�uildings, as in  other Central–European cities, while 
ground nesting �irds are almost totally a�sent from 
the ur�an area (Luniak, 1990; Bankovics, 2006). 
Furthermore, the effects of potential nest predators 
have �een studied only on �ush nests (Kurucz et al., 
2012). Most ground nesting �irds are ur�an avoiders 
and tend to show lower  environmental tolerance (Sol 
et al., 2014). We hypothesised that they are a�sent in 
ur�an environments due to human distur�ance rather 
than to  predation pressure. The aim of our study was 
to examine the daily survival rate of artificial ground 
nests in different parts of the city, across an ur�an 
gradient. Our o�jective was to determine  the extent of 
predation in green patches in the city centre, in parks 
in residential districts, and in near–natural ha�itats on 
the outskirts of the city.
Material and methods
Pécs (46° 06' 58.28'' N, 18° 13' 47.65'' E) is the lar�
gest city in �ungary’s South–Transdanu�ian region. 
Covering 162.61 km2 and having 157,680 residents, 
Pécs is surrounded from the north �y the Mecsek 
mountains and from the south �y the Pécs plain. 
The climate of influenced �y the Mediterranean; the 
mean annual temperature is 10°C and the mean 
annual precipitation is 710 mm (Kurucz et al., 2015). 
According to the European Ur�an Atlas (European 
Environment Agency–EEA), the proportion of �uilt–up 
areas decreases (96%, 48%, 13%) and green areas 
increase (4%, 52%, 87%) from the city centre towards 
the outskirts. Considering the rate of �uilt–up areas 
and land use in the city centre, in the residential 
district and in the outskirts of the city, we randomly 
selected 3 × 23 sampling points.
On 20 V 14, we created artificial ground nests in 
every selected sampling point �y digging small de�
pressions in the ground with our �oot heel. We did 
not use any lining material (e.g., feathers, �ranches, 
litter, moss, etc.) for the nest. In each artificial nest, 
we placed one quail egg and one natural coloured 
plasticine egg of the same size. This imitation eggs 
were coated with PlastiDip® and had �een aired for 
at least two weeks �efore the study �egan (Purger 
et al., 2012). The nests were then checked on days 
1 (21 V), 3 (23 V), 6 (26 V), 10 (30 V) and 15 (4 VI) 
�etween 9:00 h and 14:00 h. During nest checking, 
which lasted no longer than 5 minutes, we recorded 
the num�er of cats, and free and leashed dogs 
o�served around the nest to take into consideration 
the possi�ility that freely moving domestic animals 
found and destroyed the eggs in the artificial nests. 
We calculated nest survival �y considering every 
event (predation, mowing, running over) which had 
led to damage of any of the eggs. To separate the 
effects of predation, the daily survival rate of nests 
was calculated upon predation of quail eggs only. To 
identify nest predators we used the marks left on the 
plasticine eggs. The daily survival rate of nests and 
eggs was calculated �y the Mayfield (1975) method 
and compared using the test proposed �y Johnson 
(1979). We used a 3 × 3 contingency ta�le to compare 
the proportions of plasticine eggs left intact, removed 
(missing) or marked �y predators (mammals, �irds) in 
three different city sectors . A minimum tail pro�a�ility 
of P < 0.05 was used for all the statistical tests, and 
all tests were two–tailed.
Results
During the survey, 30.4% of the artificial ground nests 
in the city centre, 21.7% in the residential district and 
47.8% in the outskirts were damaged. Daily survival 
rates of the nests were higher in the centre 0.976 
(95% confidence limits: 95.87–99.40) and in the re�
sidential district 0.985 (95% c.l.: 97.10–99.83) than 
in the outskirts 0.959 (95% c.l.: 93.47–98.32), �ut 
none of the differences were statistically significant 
(ta�le 1). When we considered all events that had 
caused damage or destruction in the 23 ground nests 
(quail eggs and/or plasticine eggs were damaged in 
18 nests, four nests were destroyed during mowing in 
the residential district, and one nest was tread on in 
the centre), we concluded that the daily survival rate 
of ground nests was high in all city sectors (ta�le 1).
When we analysed predation on quail eggs only 
(n = 16), the survival rates of eggs (fig. 1) in the 
centre 0.987 (95% c.l.: 97.40–99.99) and in the resi�
dential district 0.997 (95% c.l.: 99.07–100.31) were 
significantly higher than in the outskirts 0.960 (95% 
c.l.: 93.66–98.37) (ta�le 1).
In the city centre three quail eggs disappeared from 
nests and one was �roken (n = 4). Five unleashed 
dogs were o�served in this city sector (n = 5). Four 
plasticine eggs disappeared, two were damaged �y 
small �irds, and one was damaged �y small mam�
mals (n = 7).
Animal Biodiversity and Conservation 40.2 (2017) 155
The survival rates of eggs were high in the residen�
tial district, despite the high num�er of cats (n = 3) and 
dogs (n = 32 leashed, n = 10 unleashed) o�served. 
During almost every checking we o�served rooks 
Corvus frugilegus and jackdaws Corvus monedula 
searching for food on the ground. Only in one nest was 
a quail egg �roken (fig. 2), pro�a�ly �y a small �ird 
whose marks were left on the plasticine egg (fig. 2).
The highest predation rate was recorded for nests 
located in the outskirts of the city. During nest checking, 
a cat was seen on one occasion and no dogs were o��
served in this area. Quail eggs disappeared from seven 
nests and in four nests we found them �roken (n = 11). 
Two of  twenty–three plasticine eggs disappeared, four 
were found to have small mammal �ite marks (fig. 2), 
and two showed �eak marks left �y small �irds (n = 8).
The num�er of plasticine eggs left intact, taken 
away, or marked �y predators indicates that the im�
pact of egg predators was small, with only  marginal 
differences (x2 = 9.423, df = 4, P = 0.051) �etween 
the three city sectors (fig. 3). 
Discussion 
The results of our study on human distur�ances and 
predation on artificial ground nests across an ur�an 
gradient suggest that nest survival is higher in �uilt–in 
areas such as the city centre and residential districts 
than in the outskirts. Moreover, if we considered only 
predation of quail eggs and ignored damage caused 
�y mowing and running over, the differences �etween 
Ta�le 1. Comparison of daily survival rates of nests. All adverse events were taken into account �ut 
only damage to quail eggs was considered a predation event. 
Tabla 1. Comparación de los índices diarios de supervivencia en el nido. Se tuvieron en cuenta todos los efectos 
adversos, pero solo se consideraron actos de depredación los daños causados en los huevos de codorniz.
                                                        All adverse events             Predation of quail eggs  
           (n = 23)                              (n = 16)
                                                     Z–value        P             Z–value             P
City centre Residential district 0.743 0.458 1.382 0.167
Residential district Outskirts 1.847 0.065 3.017  0.003**
City centre Outskirts 1.160 0.246 1.997 0.046*
Fig. 1. Daily survival rates of quail eggs (± SE) in artificial ground nests located in three different sectors of Pécs.
Fig. 1. Índices diarios de supervivencia de los huevos de codorniz (± DE) en nidos artificiales en el suelo 
situados en tres sectores diferentes de Pécs.
1.00
0.99
0.98
0.97
0.96
0.95
0.94
D
a
il
y 
su
rv
iv
a
l 
ra
te
s
P < 0.05
P < 0.01
                                  City centre        Residential         Outskirts
                                                           district
156 Bocz et al.
0     1     2     3     4     5     6     7    8     9    10
Fig. 2. A. Coated plasticine eggs with �ill imprint (pecking) of small–�odied �irds; B. Coated plasticine 
eggs with tooth imprint (gnawing) of small mammals; C. Broken quail egg.
Fig. 2. A. Huevos recubiertos de plastilina con marcas de picotazos de aves de pequeño tamaño; B. Huevos 
recubiertos de plastilina con marcas de roeduras de pequeños mamíferos; C. Huevo de codorniz roto.
Fig. 3. Rate of predation of plasticine eggs in ground nests in three different city sectors: eggs found 
intact (white �ars), eggs taken away (hatched �ars), and eggs marked �y predators (�lack �ars).
Fig. 3. Índice de depredación de los huevos de plastilina en nidos en el suelo en tres diferentes sectores 
de la ciudad: huevos encontrados intactos (barras blancas), huevos extraídos (barras rayadas) y huevos 
con marcas de depredadores (barras negras).
  A                    B                    C
                                  City centre        Residential          Outskirts
                                                           district
100
80
60
40
20
0
P
re
d
a
ti
o
n
 (
%
)
sectors were statistically significant. Our results sug�
gest that predation is low. Ground nesting crested larks 
Galerida cristata sporadically occurred in residential 
districts, �ut their �reeding was not verified. In many 
cities instead of �reeding on the ground in green areas 
they �reed on flat roofs of �uildings (Or�án, 2004). 
According to our previous o�servations, crested larks 
�reed only in the outskirts and near parking plots of 
supermarkets, and in low num�ers. Corn �unting 
Miliaria calandra, yellowhammer Emberiza citrinella, 
European nightjar Caprimulgus europaeus, common 
quail Coturnix coturnix and common pheasant Pha-
sianus colchicus sporadically �reed in near–natural 
ha�itats in the surroundings of the city (Bankovics, 
2006). In the city centre and residential districts preda�
tion on artificial ground nests was lower, �ut the effects 
of increased human presence (damage caused �y 
trampling, mowing) were stronger. Previous surveys 
Animal Biodiversity and Conservation 40.2 (2017) 157
(e.g., Gering & Blair, 1999) have shown that growing 
ur�anisation results in decreasing nest predation. In 
the outskirts of the city, however, our results showed 
that the survival of artificial ground nests was mainly 
influenced �y predation. 
Ur�an environments favour high num�ers of gen�
eralist predators (Jokimaki & �uhta, 2000; Chace & 
Walsh, 2006). Species of the Corvidae family are 
associated with ur�an areas, �ut their responses to 
ur�anisation vary greatly (Sorace & Gustin, 2009). 
Despite the frequent presence of rooks and jackdaws, 
we did not o�serve any predation activity, although 
many eggs disappeared from the nests. Our previous 
studies showed that hooded crows Corvus cornix and 
Eurasian jays Garrulus glandarius were responsi�le 
for nest predation in the city and surrounding areas. 
Mammal predators like red foxes Vulpes vulpes, �eech 
martens Martes foina and northern white–�reasted 
hedgehogs Erinaceus roumanicus are frequently 
o�served, �ut we could not demonstrate  their role in 
ground nest predation. 
The a�sence of ground nesting �ird species at our 
study site is not due to predation �ut to distur�ance 
�y humans and domestic animals (dogs and cats) in 
�uilt–up areas. In the future we could provide a chance 
for ground nesting �irds to settle and �reed in human–
dominated landscapes �y planning and creating undis�
tur�ed areas, taking advantage of the scarecrow effect 
created �y human presence that keeps predators away. 
References
Bankovics, A., 2006.  The Birds of the Mecsek Moun�
tains. Folia comloensis, 15: 317–360.
Chace, J. F. & Walsh, J. J., 2006. Ur�an effects on 
native avifauna: a review. Landscape and Urban 
Planning, 74: 46–69.
Gering, J. C. & Blair, R. B., 1999. Predation on artificial 
�ird nests along an ur�an gradient: predatory risk 
or relaxation in ur�an environments? Ecography, 
22: 532–541.
Johnson, D. �., 1979. Estimating nest success: the 
Mayfield method and an alternative. Auk, 96: 
651–661.
Jokimäki, J. & �uhta, E., 2000. Artificial nest predation 
and a�undance of �irds along an ur�an gradient. 
Condor, 102: 838–847.
Jokimäki, J., Kaisanlahti–Jokimäki, M.–L., Sorace, 
A., Fernández–Juricic, E., Rodriguez–Prieto, I. & 
Jimenez, M. D., 2005. Evaluation of the “safe nest�
ing zone” hypothesis across an ur�an gradient: a 
multi–scale study. Ecography, 28: 59–70.
Kurucz, K., Bertalan, L. & Purger, J. J., 2012. Sur�
vival of �lack�ird (Turdus merula) clutches in an 
ur�an environment: experiment with real and ar�
tificial nests. North–Western Journal of Zoology, 
8: 362–364.
Kurucz, K., Batáry, P., Frank, K. & Purger, J. J., 
2015. Effects of daily nest monitoring on predation 
rate – an artificial nest experiment. North–Western 
Journal of Zoology, 11: 219–224.
Luniak, M., 1990. Avifauna of cities in central and 
eastern Europe – results of the international inquiry. 
In: Urban ecological studies in Central and Eastern 
Europe: 131–149 (M. Luniak, Ed.). Polish Academy 
of Sciences, Warszawa. 
Mayfield, �. F., 1975. Suggestions for calculating nest 
success. Wilson Bulletin 87: 456–466.
Or�án, Z., 2004. Nest construction and roosting 
�ehaviour of a Crested Lark Galerida cristata 
population nesting on flat roofs in �ungary. Ornis 
Hungarica, 14: 1–13.
Purger, J. J., Kurucz, K., Tóth, Á. & Batáry, P., 2012. 
Coating plasticine eggs can eliminate the overesti�
mation of predation on artificial ground nests. Bird 
Study, 59: 350–352.
Sol, D., Gonzalez–Lagos, C., Moreira, D., Maspons, 
J. & Lapiedra, O., 2014. Ur�anisation tolerance 
and the loss of avian diversity. Ecology Letters, 
17: 942–950.
Sorace, A. & Gustin, M., 2009. Distri�ution of general�
ist and specialist predators along ur�an gradients. 
Landscape and Urban Planning, 90: 111–118.
Thorington, K. K. & Bowman, R., 2003. Predation 
rate on artificial nests increases with human 
housing density in su�ur�an ha�itats. Ecography, 
26: 188–196.
158 Bocz et al.


Human disturbances and predation on artificial ground nests across an urban gradient

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