ACTA BIOLOGICA SLOVENICA 
LJUBLJANA 2013 Vol. 56, [t. 1: 45–53 
ACTA BIOLOGICA SLOVENICA 
LJUBLJANA 2013 Vol. 56, [t. 1: 45–53 
Nestling 
growth 
of 
Great 
Tits 
Parus major with 
comparison 
among 
altitudes 


Rast mladicev velike sinice Parus major s primerjavo med nadmorskimi višinami 


Dejan Bordjan 

National Institute of Biology, Vecna pot 111, 1000, Ljubjana, Slovenia. 
correspondence: dejan.bordjan@nib.si 


Abstract: 
Fledgling mass can have great influence on individual’s life history 
and reflects the availability and quality of food in the breeding territory. Thus growth 
curve is used to compare the difference in the quality between different ecological 
conditions. The aim of the study was to fill the knowledge gap on nestling growth 
in Great Tit in Slovenia, to determine the influence of altitude on it and to present a 
tool for estimating age of nestlings and key dates in breeding phenology of Great Tit. 
Great Tits young were monitored using nest-boxes at three locations between years 
2010 and 2012. At two locations nest-boxes were placed on three separate altitudinal 
belts. Weight growth curve was compared with the curves from other parts of Europe. 
Growth curve from Slovenia differs in growth parameters from other European 
populations but falls within their range. Difference in growth parameters between 
separate populations probably comes from the difference in ecological conditions. 
Whencomparingthreealtitudesweightparametersofhatchlingsweresimilaratlower 
and middle but different at upper altitudes indicating that weigh growth changes with 
the altitude. Lower food abundance that comes with rising altitude may be offset by 
lowercompetitionthroughlowerbreedingdensity(hencesimilargrowthparametersin 
lower and middle altitude), but not past certain altitude. Weight parameters are useful 
when comparing different populations, but wing-length is better in determining the 
age of young in the nest. 

Keywords: Great Tit, hatchling growth, altitude, Slovenia, 

Izvlecek: 
Masa mladicev v gnezdu je pomemben dejavnik, ki ima mocan vpliv 
na življenje osebka. Masa mladicev 
v gnezdu odseva dostopnost in kvaliteto hrane 
na gnezdišcu in je zaradi tega dober pokazatelj stanja v okolju. Namen raziskave je 
bil zapolniti vrzel v znanju o rasti velike sinice na obmocju JVEvrope ter o pomenu 
nadmorskevišinenarastmladicev.Hkratibodorezultatilahkokoristilitudikotorodje 
za dolocanje starosti mladicev velikesinice v gnezdu. Meritve mladicev velike sinice 
v gnezdu so bile opravljene na treh lokacijah med leti 2010 in 2012. Na dveh so bile 
gnezdilnice postavljene na treh locenih nadmorskih višinah. Rastna krivulja za maso 
serazlikujeod krivuljizostalih delov Evropevendar jeznotrajnjihovih meja. Razlike 
verjetno izhajajo iz razlicnih ekoloških razmer v okoljih. Rast mase je podobna med 
spodnjiminsrednjimterrazlicnaodzgornjegavišinskegapasu.Podobnostnaspodnjih 
višinah je verjetnoposledica kompenzacije manjše kolicine plena z nižjo konkurenco 
zaradi nižje gostote gnezdecih parov. Kompenzacija pa je uspešna le do dolocene 
nadmorske višine, nad to pa se zmanjševanje kolicine hrane pozna na pocasnejši rasti 


Acta Biologica Slovenica, 56 (1), 2013 


mladicev. Rast mase je uporabno orodje za primerjavo med populacijami, dolžina 
peruti pa je boljše orodje za dolocanje starosti mladicev v gnezdu. 


Kljucne 
besede: 
Velika sinica, rast mladicev, nadmorska višina, Slovenija 


Introduction 


Environmental conditions change considerably 
with altitude and the most prominent of all 
is the change in ambient temperature (Newton 
1998).Individualsbreedingatthelimitofspecies 
distribution 
show 
markedly 
different 
breeding 
parameters than their counterparts in more optimalenvironments(
OrellandOjanen1980,1983, 
Veistola et al. 1994). While the onset of breeding 
within certain species consistently change along 
altitudinal 
gradient, 
with 
later 
start 
at 
higher 
elevations (Gil-Delgado et al. 1992, Belda et al. 
1998, Fargallo 2004), other breedingparameters 
like 
breeding 
density 
(Schmid 
et 
al. 
1998) 
or 
clutch 
size 
(Gil-Delgado 
et 
al. 
1992, 
Fargallo 
2004)canshowcontradictorytrendsbetweenand 
also within species. For example Fargallo (2004) 
found that the clutches of Blue Tit Cyanistes 
caeruleus were smaller with increasing altitude 
while Gil-Delgado et al. (1992) found that they 
were 
similar. 
In 
fact 
the 
clutch 
size 
can 
differ 
more among habitats than does across altitudes 
(Gil-Delgado et al. 1992). 


Fledgling mass has great influence on individual’s 
survival (Tinbergen and Boerlijst 1990, 
Barbaetal.1993,PerrinsandMcCleery2001)and 
fecundity(PerrinsandMcCleery2001).Individual 
growth rate and fledgling mass is determined by 
the amount of food they receive (Gill 1994, Keller 
and van Noordwijk 1994). Since Great Tits 
are altricial nesters all food consumed by young 
is provided by the parents (Tanner et al. 2007). 
How much food they can provide is determined 
bytheavailabilityandqualityoffoodinbreeding 
territory(GibbandBetts1963)andcanbefurther 
influenced 
by 
unfavourable 
conditions 
such 
as 
weather or competition (Minot 1981, Keller and 
Van Noordwijk 1994). 

The 
growth 
curve 
can 
offer 
comparison 
between nestling development since it is defined 
mathematicallybythreevalues:initialsize,growth 
rateandasymptoticvalue(Gill1994).Difference 
between 
two 
environments 
can 
be 
reflected 
in 

fledging mass (Richner 1989), thus growth curve 
maybeusedforcomparingthequalitydifference 
betweenbreedingenvironmentswithintherangeof 
species(Janssensetal.2003,Eevaetal.2009).Also 
growthparameterscanvaryconsiderablybetween 
different populations (Barba et al. 1993), though 
this does not seem to be a general rule (King and 
Hubbard1981).Therearesomestudies thatoffer 
growth data of the Great Tit from other parts of 
Europe (Barba et al. 1993, Janssens et al. 2003, 
Eeva et al. 2009) but there hasn’t been a study 
yet considering South-East Europe. In fact, apart 
fromstudiesofDolenec(2005)andDolenecetal. 
(2005)remarkablylittleisknownaboutGreatTit 
inthisregion.ScientificpublicationsonSlovenian 
populationofGreatTitareevenscarcer.Thereare 
only a few reports about number of ringed birds 
per year and about exceptional recoveries (Božic 
2009, Šere 2009). 


Considering the altitude, there are some studies 
about influences on breeding phenology and 
clutch size of Tits in Europe (Gil-Delgado et al. 
1992,KrementzandHandford1984,Sanz1998), 
butnonethatusesaltitudeasaninfluencingfactor 
on growth parameters. 


With 
the 
present 
study 
I 
aimed 
to 
fill 
the 
knowledge gap on Great Tits nestling growth in 
Slovenia. I also aimed to use weight of nestlings 
tocompareinfluenceofenvironmentalconditions 
atdifferentaltitudes.Sinceconditionsfornesting 
deteriorate with the rising altitude, e.g. less food 
(Hodkinson 2005), I hypothesise that this results 
alsoinslowernestlinggrowthathigheraltitudes. 
Presented data on growth curve of young Great 
Titsmightalsoserveasatoolforotherresearchers 
to estimate key dates in breeding phenology of 
GreatTit(startofincubation,hatchingtime,ageof 
nestlings, etc.) from body part measurements. 

Methods 
andmaterials 


BreedingbiologyofGreatTitusingnest-boxes 
wasstudiedatthreelocationsinSloveniabetween 


Bordjan: Growth of young Great Tits 


years2010and2012.Atthefirstlocation,Ljubljana 
(300 m asl), five nest-boxes were set to measure 
hatchlings weight and wing-length. Location 1 
is a small forest fragment dominated by Beech 
Fagus sylvatica, White Fir Abies alba andNorway 
Spruce Picea abies.Thislocationwaschosendue 
toitseasyaccessibilityandcomparablealtitudeto 

study sites in other European countries (Barba et 

al. 1993). Hatchlings were measured two to four 
times a week. When their weight reached more 
than 10 g they were ringed and individual’s size 
was monitored then after. The nest-box visiting 
frequencywashighenoughevenbeforehatching, 
so the first measurements of all chicks have been 
taken within two days after hatching. 


Atlocations2and3,Mt.KrimandMt.Pohorje 
respectably, nest-boxes wereplaced in similar habitat 
(mixed forest dominated by Beech, White Fir 
andNorwaySpruce)onthreealtitudinalbeltswith 
anaveragealtitudeof335(Lower),654(Middle) 
and1023masl(Upperbelt).Oneachoftheupper 
two belts 40 nest-boxes were placed while on the 
lower one 32 were placed. At locations 2 and 3 
nest-boxes were checked once a week. Number 
of nest-boxes at each location has corresponded 
to our capability to survey them and was higher 
on higher altitudesdue to lower breeding density 
of Great Tits there (Schmid et al. 1998). 

Measurements from location 1 were used to 
produce logistic growth curves for wing-length 
and body-weight. This was done by calculating 
growthconstant(k),whichdenotesrelativespeed 
ofgrowing,andtimeittakesforhatchlingtoreach 
half theirweight at fledging (t50) (Ricklefs 1967, 
Tome 
1995). 
Asymptotic 
value 
was 
estimated 
fromindividualchicksattheageof17days,since 
at about that age they leave their nest (Perrins 
and 
McCleery 
2001) 
and 
the 
weight 
of 
chicks 
out off the nests levels of or may even drop after 
emergence (Tome 1995). Weight growth curve 
was than compared with the curves from other 
partsofEuropee.g.Spain,Finland,GreatBritain, 
Germany and Netherland with the use of growth 
parameters published by Barba et al. (1993). 


Fromthewing-lengthgrowth curveobtained 
fromnestlingsatlocation1ageofhatchlingfrom 
nests at locations 2 and 3 was estimated with an 
accuracy of ± 1 day. Then weight growth curves 
forchicksfromallthreealtitudeswerecalculated 
separately (Ricklefs 1967, Tome 1995). Average 

weightofnestlingsinindividualnestonparticular 
day from locations 2 and 3 was compared with 
the calculated value from nestlings in Ljubljana. 
The difference between these weights was used 
to compare nestling’s condition among altitudes. 
Onlydatafromnestlingsattheagebetween11and 
15 days was used, when growth is most constant 
and overlapping among estimated age classes is 
lesslikely.Statisticalsignificancewastestedwith 
the use of nonparametric Kruskal-Wallis statistic 
test (PAST 2.03). 

Results 


Five nests and 35 hatchlings were monitored 
atlocation1.Onenestcontainingeighthatchlings 
failedanditsmeasurementwerelaterdisregarded. 
At locations 2 and 3 altogether weekly measurements 
from 90 nests containing 644 hatchlings 
were gathered. Of those 369 hatchlings from 52 
nestwerefromlower,235(31nests)frommiddle 
and 40 (7 nests) from upper altitudinal belts. 


The growth parameters from location 1 were 
for the wing-length: k = 0.347; t50 
= 9.252; and 
the body weight: k = 0.430; t50=5.928.Thesetwo 
parameters were used for modelling wing-length 
and weight growth curves respectably (Fig. 1). 
Measurements and estimated values for wing-
length at location 1 are presented in Tab. 1. 


Weight growth curve of nestlings from Slovenia 
falls 
within 
the 
range 
of 
the 
curves 
from 
otherpartsofEurope(Fig.2).Asymptoticweight 
is 
second 
only 
to 
that 
from 
Great 
Britain 
and 
only marginally higher than the one from Spain. 
Growth constant is highest and t50 
is the second 
lowest behind Finland (Tab. 2). 


Weight growth curves for location 1 and for 
lower and middle belts from locations 2 and 3 
are similar (Fig. 3). Curve from the upper belt is 
somewhat lagging 
behind the rest. Nestlings at 
the upper belt had lower asymptotic value, lower 
growth constant and it took them longer to reach 
50%ofasymptoticvalue(Tab.2).For11-15days 
old chicks weights at lower and middle altitudes 
were similar, but both were statistically heavier 
from those at the upper altitude (Kruskal-Wallis 
All: H3 
= 7.18, p < 0.05; Lower / Middle: p = 
0.905; Lower / Upper: p < 0.05; Middle / Upper: 
p < 0.01). 



Acta Biologica Slovenica, 56 (1), 2013 


Figure 117
Figure 1: 
Calculated 
logistic growth curves for weight (asymptotic value: 18.1g) and wing-length (asymptotic 
value: 72mm) for Great Tit Parus major hatchlings in Ljubljana with values shown. Number of nestling 
monitored: 27. 

Slika 1: 
Izracunanalogisticnarastnakrivuljazamaso(asimptoticnavrednost:18.1g)indolžinoperuti(asimptoticna 
vrednost: 72mm) mladicev velike sinice Parus major v Ljubljani s prikazanimi vrednostmi. Število 
spremljanih mladicev: 27. 


Table 1: 
ResultsofnestlingmeasurementsinLjubljanawithaverage,minimalandmaximalmeasuredwing-length 
compared with estimated wing-length gained from logistic curve. N represents number of measured 
nestling at 
particular age. 


Tabela 1:Rezultati merjenj mladicev v Ljubljani s 
prikazano povprecno, minimalno in maksimalno izmerjeno 
dolžino peruti primerjano z izracunano dolžino peruti iz logisticne krivulje. N predstavlja število izmerjenih 
mladicev za posamezno starost. 

Age Average 
wing-length 
(mm) 
StD 
Min 
– 
max 
wing-length 
(mm) 
N Estimated 
wing-length 
(mm) 
0 
4.3 
0.5 
4-5 
6 
4.6 
1 
5.8 
0.5 
5-6 
4 
5.9 
2 
7.1 
0.7 
6–8 
7 
7.6 
3 
9.6 
0.9 
8–11 
13 
9.6 
4 
12.4 
1.1 
11-14 
16 
12.2 
5 
14.7 
1.3 
13-16 
11 
15.2 
6 
19.5 
1.6 
15-21 
15 
18.7 
7 
24.0 
1.4 
21-26 
20 
22.7 
8 
29.1 
1.6 
26-31 
15 
27.1 
9 
33.1 
1.4 
30-36 
15 
31.7 
10 
37.5 
1.3 
34-39 
19 
36.5 
11 
42.3 
2.0 
38-45 
12 
41.3 
12 
46.1 
1.9 
43-50 
19 
45.8 
13 
47.9 
2.1 
44-52 
14 
49.9 
14 
50.8 
1.4 
48-53 
8 
53.6 
15 
55.9 
0.8 
55-58 
14 
56.8 
16 
60.0 
0.7 
59-61 
9 
59.5 
17 
62.3 
1.3 
61-44 
4 
61.7 



Bordjan: Growth of young Great Tits 


Figure 219
Figure 2: 
CalculatedlogisticgrowthcurvesforhatchlingsweightofGreatTitParus major fromseparateEuropean 
populations. Curves from other parts of Europe are from Barba et al. (1993). 


Slika 2: 
Izracunanalogisticna rastna krivulja za maso mladicev velike sinice Parus major iz locenih evropskih 
populacij. Rastne krivulje za ostale dele Evrope so iz Barba et al. 1993. 


Table 2: 
Growth parameters of Great Tit Parus major nestlings from different European populations and different 
altitudes. Growth parameters published by Barba et al. (1993) were used for other parts of Europe. 


Tabela 2:Rastni parametrimladicev velikesiniceParus major z razlicnih delov Evrope in locenih višinskih pasov. 
Rastni parametri objavljeni v Barba et al. (1993) so bili uporabljeni za ostale dele Evrope. 

Population 
Asymptotic 
weight 
(g) 
Growth 
constant 
(k) 
t50 
Great Britain 19.3 
0.413 
6.486 
Spain 17.9 
0.389 
5.695 
Netherland 
17.6 
0.390 
5.970 
Germany 
17.1 
0.412 
5.964 
Finland 16.7 
0.418 
5.075 
Ljubljana 18.1 
0.430 
5.422 
Lower 
18.2 
0.420 
6.173 
Middle 
18.0 
0.436 
6.382 
Upper 17.5 
0.426 
7.133 


t50 – time it takes hatchlings to reach 50% of asymptotic weight 



Acta Biologica Slovenica, 56 (1), 2013 



Figure 3: 
Calculated 
logistic weight growth curves for hatchlings of Great Tit Parus major from Ljubljana and 
separate altitudinal belts from Mt. Krim and Mt. Pohorje. 


Slika 3: 
Izracunanalogisticna rastna krivulja za maso mladicev velike sinice Parus major iz Ljubljane in locenih 
višinskih pasov na Krimu in Pohorju. 


Discussion 

Weigh growth of Great Tit nestlings changes 
withthealtitude(Fig3.)butitseemsthatthisdoes 
not happen linearly. The nestlings from middle 
andloweraltitudeshavesimilargrowthcurveand 
similar weight at the age of 11 to 15 days. Both 
indicate similar food availability for the young. Al-
thoughconditionsusuallydeterioratewithaltitude 
(Hodkinson 2005), lower food abundance in the 
field, one of the major factors influencing growth 
(Keller and van Noordwijk 1994), may be offset 
bythelowercompetitionthroughlowerbreeding 
density (Schmid et al. 1998). This could explain 
similarresultsofgrowingparametersfromlower 
andmiddlealtitudeonourstudysite–therewere 
more nest-boxes occupied on lower as on middle 
altitude indicating higher breeding density. But 
this obviously has a limit. The upper altitude in 
our study site has even lower breeding density (7 
compared to 31 nests at middle altitude with the 
samenest-boxavailability)butalsolowerweight 
growth rate of the nestlings. It seems that presumably 
larger home-ranges of pairs on the highest 

altitudescannotoffsetlowerfoodavailability.Thus 

hypothesis that higher altitude reduces average 

nestlings weight can be accepted but only after 

the effect of altitude can no longer be offset by 

lower intraspecific competition. 


Barbaetal.(1993)foundthatthegrowthrates 
differbetweenpopulationsofGreatTit(Table1), 
and this also applies for Slovenian 
population, 
which is none the less within the range of other 
growth rates. What is more, growth rate differs 
alsobetweenhabitats(Richner1989)andclimatic 
zones (Barba et al. 1993). Presented data shows 
thatthesameappliesalsoforaltitudes.Difference 
ingrowthparametersbetweenseparatepopulations 
probablycomesfromthedifferenceinecological 
conditions in which a particular population lives 
(Barba et al. 1993). Lower asymptotic weight in 
Finland population and higher growth constant 
is probably the response to the shorter breeding 
period (Veistola et al. 1994). On the other hand 
reasons 
affecting 
higher 
asymptotic 
weight 
in 
Great Britain population are harder to explain, 
but more stable and milder climatic conditions 
may suggest the answer. 



Bordjan: Growth of young Great Tits 


Weight is usefulfor studies of environmental 
differencesbetweenpopulationsasshownhigher 
up,butislesssofordeterminingageofyounginthe 
nest.Notonlythattheweightdiffersbetweenbirds 
from different climatic zones (Barba et al. 1993), 
altitudes (this study),alongpollutiongradient(Eeva 
et al. 2009) and habitats (Richner 1989), it also 
changes between years (Orell 1983) and differs 
between sex (due to different asymptotic weight; 
females are lighter) and the first and the second 
clutches (Orell 1983). Wing-length on the other 
handislessvariableparameter(Tome1995,Tome 
2007) and thus wing measurements for ageing 
youngGreatTitsinthenestseemsabetterchoice. 

Conclusions 

Altitude influences weight-grow parameters 
in 
Great 
Tit 
nestlings, 
but 
only 
on 
the 
highest 
altitudes, while on the middle altitudes deteriorated 
environmental 
conditions 
are 
possibly 
offsetbylowerbreedingdensityandhencelower 
competition. 


Growth rates differ between populations of 
Great 
Tit, 
and 
this 
applies 
also 
for 
Slovenian 
population,whichisnonethelesswithintherange 
of other growth rates. 

Weight is usefulfor studies of environmental 
differencesbetweenpopulations,butwing-lengthis 
a better tool for determining the age of young. 


Povzetek 


Masa mladicev v gnezdu je pomemben dejavnik, 
ki ima mocan vpliv na nadaljnjo življenje 
osebka. Pogosto imajo mladici z vecjo maso vec 
potomcev. Masa mladicev v gnezdu odseva tudi 
dostopnost in kvaliteto hrane na gnezdilnem terito-

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