# The Breeding colonies, population growth and breeding success of the Dalmatian pelican Pelecanus crispus in Greece: a country-wide perspective, 1967-2021

Catsadorakis Giorgos, Olga Alexandrou, Dionyssia Hatzilacou, Ioannis Kasvikis, Maria Katsikatsou, Spyros Konstas, Myrsini Malakou, Demetres Michalakis, Theodoros Naziridis, Haris Nikolaou, et al.

<figure><img src="image_1.png" /></figure>

## ► To cite this version:

Catsadorakis Giorgos, Olga Alexandrou, Dionyssia Hatzilacou, Ioannis Kasvikis, Maria Katsikatsou, et al.. The Breeding colonies, population growth and breeding success of the Dalmatian pelican Pelecanus crispus in Greece: a country-wide perspective, 1967-2021. European Journal of Ecology, 2024, 10 (1), 10.17161/eurojecol.v10i1.20352. hal-05330308

HAL Id: hal-05330308

https://hal.science/hal-05330308v1

Submitted on 24 Oct 2025

HAL is a multi-disciplinary open access
archive for the deposit and dissemination of sci-
entific research documents, whether they are pub-
lished or not. The documents may come from
teaching and research institutions in France or
abroad, or from public or private research centers.

L'archive ouverte pluridisciplinaire HAL, est
destinée au dépôt et à la diffusion de documents
scientifiques de niveau recherche, publiés ou non,
émanant des établissements d'enseignement et de
recherche français ou étrangers, des laboratoires
publics ou privés.

<figure><img src="image_2.png" /></figure>
<figure><img src="image_3.png" /></figure>

BREEDING COLONIES, POPULATION GROWTH AND BREEDING SUCCESS OF THE DALMATIAN PELICAN *PELECANUS CRISPUS* IN GREECE: A COUNTRY-WIDE PERSPECTIVE, 1967-2021

CATSADORAKIS GIORGOS¹*, OLGA ALEXANDROU¹, DIONYSSIA HATZILACOU², IOANNIS KASVIKIS²,
MARIA KATSIKATSOU², SPYROS KONSTAS², MYRSINI MALAKOU¹, DEMETRES MICHALAKIS²,
THEODOROS NAZIRIDIS², HARIS NIKOLAOU¹, NIKOLAOS NOULAS³, DANAE PORTOLOU³,
YIANNIS ROUSSOPOULOS⁴, IOANNIS VERGOS², ALAIN J. CRIVELLI⁵

1= Society for the Protection of Prespa,

catsadorakis@spp.gr, o.alexandrou@spp.gr, m.malakou@spp.gr, h.nikolaou@spp.gr

2= Natural Environment & Climate Change Agency (N.E.C.C.A.)

d.hatzilacou@necca.gov.gr, i.kasvikis@necca.gov.gr, s.konstas@necca.gov.gr, d.michalakis@necca.gov.gr, th.naziridis@necca.gov.gr, i.vergos@necca.gov.gr, mkatsik@gmail.com

3= Hellenic Ornithological Society, nicolanoula@hotmail.com, dportolou@ornithologiki.gr

4= Aitoliko, Greece giannisolga@yahoo.gr

5= Station Biologique de la Tour du Valat, 13200 Arles, France, baluche9@gmail.com

*corresponding author: c/o Society for the Protection of Prespa, Lemos, 53 150 Florina,
Greece. Tel. 23850 51211.

Abstract

Greece holds the third largest breeding population of Dalmatian pelican in the world. We present data about the establishment and growth, breeding performance and conservation status for all current six colonies of the species in Greece for the last 40 years. Colony surveys were carried out with various methods, adapted to the particularities of each wetland and availability of resources, and targeted estimating the number of Apparently Occupied Nests and numbers of near-fledged young via direct counting, either during on-site visits or from vantage points, and recently, counts on photos taken by drones flown one or more times during breeding. Main features of wetlands and colonies are described. The overall breeding population in Greece grew from ca 100 nests in two colonies in 1967 to over 2,000 nests in six colonies in 2012, exhibiting an annual growth rate of 7.9%. Younger colonies show high annual growth rates clearly attributed to immigration, while older colonies have growth rates less than 10%. Natural factors at a local and regional scale, as well as anthropogenic factors, that could have contributed separately or in combination to an increase in Dalmatian pelicans in Greece during the last 40 years, are discussed.

**Key Words:** Dalmatian pelican, breeding, colonies, population trends, breeding success, Greece, long-term data series, seabirds, waterbirds, colony growth
## INTRODUCTION

The value of long-term ecological studies has been repeatedly acknowledged (Strayer et al. 1986; Cody & Smallwood 1996; Collins 2001; Magurran et al. 2010). They have substantially improved our understanding of the life history strategies of animals. Through such studies we try to detect changes in size and other population parameters and correlate them with environmental events and variables. We also try to document the consequences of stochastic events (such as mass mortality, disease, preparation, flood, drought, etc) upon the year-to-year variation in productivity and survival, as well as to collect evidence for density-dependent processes in population regulation (Wooler et al. 1992). Some patterns of fluctuation in bird populations can only be detected by long-term studies (Newton 1998). Such studies are also needed in order to understand complex system dynamics, all of which may result from natural and anthropogenic causes (Franklin 1989). Long-term datasets are also useful for providing guidance in conservation management, assessing the efficiency of conservation policies and informing public policy decisions (Collins 2001; Magurran et al. 2010; Reif 2013).

Particularly for seabirds and waterbirds, long-term studies are not only crucial for their conservation, but the past decades have shown that there is also a need for spatial integration in their management, which must be expanded to a landscape scale, at the level of many square kilometres. Equally important is the integration of population dynamics with habitats, such as the identification of “source” and “sink” populations, for example (Erwin 2002). Aggregated results from many different study plots can clearly give a more representative picture of regional dynamics than studies at a single study site (Newton 1998).

The Dalmatian pelican (hereafter DP) *Pelecanus crispus* Bruch 1832, although principally a freshwater species, is listed among seabirds due to its taxonomic position in the Pelecanidae and many of its life history traits, which it shares with real marine birds (Schreiber & Burger 2002). It has a Eurasian distribution, from Montenegro in the west, to China in the East, whilst its global population trend is increasing after a decline that reached its lowest in the mid-20th century (Crivelli & Schreiber 1984). Its global conservation status was downgraded from “Vulnerable” to “Near Threatened” in 2017 (BirdLife International 2021). After Kazakhstan and Russia, Greece is the third most important country for this species in the world, as it hosts 20-25% of the global population (Catsadorakis & Portolou 2018) and is the species' stronghold in the Black Sea-Mediterranean flyway.

Up to the late 1970s, little was known about the status, populations and ecology of this species outside the former Soviet Union. In 1977, the French Research Centre Tour du Valat launched a long-term project (entitled: “In-

ternational Pelican Research and Conservation Program”, IPRCP), led by A. J. Crivelli for over 30 years, aiming to explore the ecology and ensure the conservation of the DP. A network of local partners in several countries was gradually built in the 1980s, with more intensive work carried out in Prespa and in Amvrakikos and, later, other wetlands of Greece.

After the 1990s, knowledge and understanding of the species' needs improved, legal protection was enhanced and, combined with environmental changes and conservation measures in various countries, resulted in a population expansion and the formation of new colonies. Research and conservation work carried out in Greece played a crucial role in the regional population recovery, principally due to the spectacular increase of the Prespa colony (Doxa et al. 2010; 2012a; 2012b; Deinet et al. 2013; Catsadorakis 2015; Barboutis et al. 2021). The DP is one of the few bird species in Greece for which quite detailed population and breeding performance data have existed for many years, but which have remained unpublished so far (but see Crivelli 1983; 1987; Crivelli et al. 1991; Hatzilacou 1992; Crivelli et al. 2000). Conditions, however, have changed radically in the last 20 years, not least with the appearance of new colonies. In this paper, we present up-to-date data about the establishment, growth, breeding performance and conservation status of all six colonies of the species in Greece over the last 40 years. We also discuss the local and regional natural factors that may have affected growth, either in individual colonies or in groups of colonies, as well as human effects on the colonies. These data will offer insightful conclusions for management and conservation everywhere across the species range, and particularly for other neighbouring populations in Albania, Bulgaria, Romania and Turkey, as the species is highly management-dependent (Grace et al. (2021)). Furthermore, they can be useful for the envisioned re-introductions of the species in several northern and central European countries and the British Isles (Kurstjens et al. 2021; Crees et al. 2022).

## STUDY AREAS

The two adjoining Prespa lakes (Fig. 1a, Table 1) are situated in a closed mountain basin. Mikri Prespa Lake is eutrophic and c. 47 km² in area, with a maximum depth of 8.4m. Megali Prespa Lake is mesotrophic, c. 250 km² and has a maximum depth of c. 50m. Both lakes are cyprinid dominated, with the more abundant species being *Alburnus belvica* and *Rutilus prespensis*. Lake Cheimadi-tis (Fig. 1b, Table 1) is one of four hydraulically connected lakes, in a joint catchment of 2,145 km². Reedbeds consisting mainly of *Typha* spp. and *Schoenoplectus lacustris* and less of *Phragmites australis* cover less than 20% of the lake surface. Average depth is less than one metre. The most abundant fish species are *Lepomis gibbosus*, *Al-burnus thessalicus* and *Carassius gibelio*, (Petriki 2015).
<figure><img src="image_4.png" /><figcaption>**Figure 1:** The locations of Dalmatian pelican colonies in Greece. Full triangles denote active colonies, open triangles denote former colonies. 1a: Prespa lakes, 1b: Lake Cheimaditis, 1c: Lake Kerkini, 1d: Amvrakikos wetlands, 1e: Messolonghi wetlands, 1f: Karla Reservoir.</figcaption></figure>
In its present form, Lake Kerkini (Fig. 1c, Table 1) is a reservoir on the river Strymon, created by damming the river in 1982 for irrigation and flood control purposes. Its area of open water fluctuates from 5,000 to 7,300 ha according to the water level, which varies seasonally between 31 and 35.50 m asl. It is one of the most important waterbird breeding and wintering sites in Greece (Handrinos et al. 2015) and is also its most productive inland freshwater body (Tatarakis 1995; Petriki & Bobori 2009). *Carrasius gibelio* and *Cyprinus carpio* are fished in high quantities. Amvrakikos (Fig. 1d, Table 1) is a closed gulf (470 km²), separated from the Ionian Sea by a narrow mouth, and has a maximum depth of 65 m and a seabed covered by mud or sand (Tsolakos et al. 2020). Two rivers discharge into the gulf, which includes 14 lagoons covering ca 86 km² (Katselis et al. 2013). Most of the lagoons are operated as natural fish farms, i.e., parallel to the traditional use there is restocking with gilthead sea bream *Sparus aurata* and European sea bass *Dicentrarchus labrax*.

Messolonghi (Fig. 1e, Table 1) consists of a double delta, lagoons and salt and freshwater marshes, coastal spits with dunes and salt pans (Pergantis & Handrinos 1992; Zalidis & Mantzavelas 1994). The maximum depth of most lagoons is 1.5 m and the main lagoons are the Kentriki (11,2 km²), Aitoliko (14 km²) and Kleisova (3 km²). Fisheries exploitation relies on the seasonal migration of fish from the open sea to the lagoons and the summer-to-winter offshore fish migration (Hotos & Katselis 2011). Karla Reservoir (Fig. 1f, Table 1) was built in the early 2000s in a part of a drained lake and started filling with water in 2009. The mean water depth is 1.5 m. Extensive cyanobacterial blooms took place there between 2010 and 2018 (Oikonomou et al. 2012; Gkelis et al. 2017; Papadimitriou et al. 2018). More detailed data about each colony and its history are included in Table S1.

## METHODS

From 1967 to 1982 all available data on colony sizes at Amvrakikos and Prespa were collected from a wide variety of published and unpublished sources and are of limited accuracy, mostly collected in one visit to the colony. The number of Apparently Occupied Nests (AON) was counted on the spot, but the estimates of numbers of breeding pairs were often just an approximation. These data (presented in Table S2) are useful in giving just a rough measure of the breeding population size in that period and were not treated further in this paper.

After 1982 the census of the colonies was carried out with a variety of methods, adapted to the particularities of each wetland and availability of resources. Nonetheless, all methods aimed at estimating the number of AON and fledged young produced. The primary concern was to keep researcher disturbance to a minimum.

At Prespa, between 1983 and 2000 colonies were

censused from vantage points with telescopes and visits were paid every 7-15 days, which eventually became sparser as the colony grew and disturbance multiplied. After 2000 colony visits stopped and nest survey was only carried out from vantage points, while number of young fledged was impossible to census. Drones were used to photograph colonies monthly (February-July) and count AON nests and young on photos after 2014. The number of AON at Kerkini was assessed by observers circling the platforms in boats, taking photos from several angles. In 2013 a birdwatching tower was built close to the platforms from which observation was made with telescopes, while drone photos were also used after 2017. Surveying at Cheimaditis was carried out monthly (March-July) by taking aerial photos of the colony with a drone and counting AON and near-fledged young on photos. At Karla, until 2014, the number of AON was estimated annually through observations from vantage points and one visit to the colony near the end of the brooding period. After 2014 drone photos were taken monthly. At Amvrakikos, colonies were approached carefully by boat early in the breeding season and the number of AON was estimated from several spots around the islands, while a few, well-timed visits were made at later stages to count near-fledged young.

At Messolonghi, in early spring, colonies were approached carefully on boats twice and the number of AON was estimated from several spots around the islands, while two visits were paid at later stages of the breeding cycle to count near-fledged young. After 2019 only drone photos were used for both estimation of colony size and breeding success.

In this paper, when two groups of nests lie more than 3kms apart, are arbitrarily considered as two discrete colonies (cf. Coulson 2002). However, for practical reasons, we refer to “Site X colony” for all colonies lying within a specific wetland, even though in the text we clarify that there is more than one colony at this site. Discrete groups of nest-clumps within a colony are termed “sub-colonies” (e.g., two islets with nests situated a few metres apart), whilst the “breeding unit” is used *sensu* Crivelli (1987) and Crivelli et al. (1998), i.e. equivalent to the term “colony” used by Knopf (1979) and Johnston (2016): a spatially rather discrete group of contiguous nests, within which birds breed more or less synchronously.

Annual growth rate of colonies was calculated from the formula:

$$ \frac{V_{final} - V_{initial}}{V_{initial}} \times 100 $$

Where: $V_{final}$ = population size of the last year, $V_{initial}$ = population size of the initial year and N = number of annual cycles that lapsed between initial year and final year.
<table><caption>Table 1: Main attributes of the wetlands hosting pelican colonies in Greece</caption><thead><tr><th></th><th>PRESPA</th><th>KERKINI</th><th>KARLA</th><th>CHIMADITIS</th><th>AMVRAKIKOS</th><th>MESSOLONGHI</th></tr></thead><tbody><tr><td>Names of waterbodies included</td><td>Lake Mikri (Lesser) Prespa & Lake Megali (Great) Prespa</td><td>Kerkini Reservoir and parts of River Strymon</td><td>Karla Reservoir and smaller reservoirs</td><td>Lake Cheimaditis</td><td>Tsoukalio lg., Logarou lg., Rodia lg., Tsopeli lg., Lake Voulkaria, etc.</td><td>Kleisova lg., Kleisova lg., Kentriki lg., Aitoliko lg., River Evinos, etc</td></tr><tr><td>Max. surface area of water bodies (km²)</td><td>307</td><td>73</td><td>38</td><td>11</td><td>170</td><td>160</td></tr><tr><td>Catchment area (km²)-watershed</td><td>1,395</td><td>>17,000</td><td>1,171</td><td>103</td><td>>4,200</td><td>>630</td></tr><tr><td>Wetland types included</td><td>Freshwater lakes, ponds, wet reedbeds</td><td>Dam lake and inner river delta</td><td>Shallow reservoir</td><td>Freshwater lake, wet reedbeds</td><td>Coastal lagoons and wetland complex: saltwater lagoons, brackish water lagoons, freshwater lakes, and streams, reedbeds</td><td>Coastal lagoons and wetland complex: saltwater lagoons, brackish water lagoons, freshwater lakes, and streams, reedbeds</td></tr><tr><td>Altitude (average, m asl)</td><td>840</td><td>35</td><td>46</td><td>591</td><td>0</td><td>0</td></tr><tr><td>Climate type</td><td>Cfb-Temperate</td><td>Cfa-Humid Subtropical</td><td>Csa-Hot summers Mediterranean</td><td>Cfb-Temperate</td><td>Csa-Hot summers Mediterranean</td><td>Csa-Hot summers Mediterranean</td></tr><tr><td>Salinity</td><td>Freshwater</td><td>Freshwater</td><td>Freshwater</td><td>Freshwater</td><td>Saline-brackish-fresh</td><td>Saline-brackish-fresh</td></tr><tr><td>Principal human activities</td><td>Agriculture, livestock rearing, fishing, tourism</td><td>Agriculture, livestock rearing, fishing, nature tourism</td><td>Livestock rearing, agriculture</td><td>Livestock rearing</td><td>Fishing, fish-farming, agriculture, livestock rearing, hunting, tourism</td><td>Agriculture, fishing, fish-farming, livestock rearing, hunting, tourism</td></tr><tr><td>Main practices affecting pelicans & pelican habitats</td><td>None</td><td>Water level management, some disturbance by fishers and visitors in boats</td><td>Hydrological manipulations</td><td>Some disturbance by fishers</td><td>Disturbance by fishers, hunters, poachers</td><td>Disturbance by fishers, hunters, poachers</td></tr><tr><td>Hydrology & water quality issues</td><td>Lowering water levels due to climate change and abstraction, ongoing eutrophication</td><td>Quick water level increase by 5-6 m in spring, high sedimentation rates</td><td>Nutrient-laden waters, no renewal, cyanotoxin events</td><td>Water abstraction for power plant cooling</td><td>Decreasing sedimentation, eutrophication, less freshwater to lagoons</td><td>Decreasing sediments, less freshwater to lagoons</td></tr><tr><td>Legislative/Protection Status</td><td>National Park, Ramsar wetland, SCI, SPA</td><td>National Park, Ramsar wetland, SCI, SPA</td><td>SCI, SPA, Ecodevelopment area</td><td>SCI, SPA</td><td>National Park, Ramsar wetland, SCI, SPA</td><td>National Park, Ramsar wetland, SCI, SPA</td></tr></tbody></table>
Throughout the text the “Eastern population group” refers to the colonies at Prespa, Kerkini, Karla and Cheimaditis, while the “Western population group” refers to the colonies at Messolonghi and Amvrakikos. Based on ringing data, the exchanges -cf. gene flow- between these two groups are very limited. It has been supposed that this is due to the role of the Pindus mountain range (A.J. Crivelli, unpublished data, Catsadorakis 2016) as a physical barrier to movements.

## RESULTS

### Breeding population trends and breeding success per colony

In Prespa two periods of severe drought (2001-02 and 2007-08), when pelican breeding numbers were supressed due to shortage of nesting places, were followed by spec- tacular increases in the next breeding period (Fig. 3). Nest numbers rose from 114 in 1983 (Crivelli 1987) and lev- elled off at around 1,226-1,585 during 2017-2021, show- ing a c. 6.8% annual growth (Fig. 3). In the last ten years BS has been 0.78 ± 0.20 (SD) fledged young/AON, n=7), but has significantly declined compared to figures for the 1980s and 1990s (1.15 ± 0.20, n=15) (t=-3.53, df=20, p=0.002). (Periods compared are 1984-1998 and 2014- 2021). The decline indicates density dependence effects.

and number of nests, which varies according to the available surface, which in turn is based on management decisions. The Kerkini colony shows the highest average BS of all the colonies in Greece, with 1.11±0.21 fledged young/AON (n=9), and the least variability.

Catsadorakis (2019) discussed the establishment and growth of the DP colony in the Karla Reservoir, which started with one pair in 2011 and reached 445 AON in 2017 (Fig.3), showing an annual growth of 176.4%. This colony shows the lowest BS of all colonies in Greece, equal to 0.69±0.21 fledged young/AON (n=8).

In Lake Cheimaditis DPs nest on 4-6 reed rhizome “islands” (Fig. 2.3, Table 2), like those at Lake Mikri Pre- spa. Within five years (2017-2021) the colony showed an annual growth rate of c.18% but it has been irregularly af- fected by human disturbance. The BS in the last five years has been 0.75±0.31 fledged young/AON.

From 1987 to 2010 the breeding population at Am- vrakikos quadrupled, although in some years BS was heavily affected by human disturbance (Table 2) and for the period 1985-2010 it was 0.87 ± 0.16 (SD), (range 0.58- 1.16, n=26; D. Hatzilacou & AJ Crivelli, presented at the 1st Meeting of Pelican specialists, Pyli, Prespa, Greece, 1-2 May 2012). In the last eleven years, the birds have still bred on Tsoukalio and Logarou lagoons, and the BS has The annual growth of the Kerkini colony was c. 16.4% (n=19 years) (Fig. 3) but varied greatly according to the final year used for calculation (16.4%-25% for the last five

years) been similar to the previous period, though still ir- regularly affected by disturbance (range 0.30-1.26, mean 0.91 ± 0.32 (SD), n=7). The annual growth rate of the colony at Messolonghi has been around 34% for 11 years (2011-2021). The BS of the colony is 0.88 ± 0.30 (SD), (range 0.57-1.37, n=9), (see Table S3).

Among colonies, Kerkini shows the highest and least varying mean BS (Fig. 4), which is significantly higher than that of Prespa, Cheimaditis and Karla (Mann-Whit- ney pairwise test 0.017, 0.045 and 0.003 respectively) and is also higher, but not significantly, that that of Amvraki- kos and Messolonghi (Mann-Whitney pairwise test 0.223 and 0.133 respectively).

### Regional and overall breeding population in Greece

According to all available data (Catsadorakis 2019, Bounas et al. 2022) the Eastern population group (1,820- 1,930 AON in the last five years) exhibits a high degree of interconnectedness in terms of origin of breeders and im- migration, as well as because many birds spend large parts of their annual cycle in two or more of them (Efrat et al. 2018, Georgopoulou et al. 2023). The annual growth rate of the whole Eastern population group is ca 7.7% (1983- 2021), (Fig.5A).

The Western population group (200-400 AON in the last five years) currently consists of two colony-sites and four colonies (2 at Amvrakikos and 2 at Messolonghi). Its overall annual growth rate is ca 9.6 % (1983-2021, n=38) and, while Amvrakikos seems to have levelled off, Messolonghi, a more recent colony, continues to increase (Fig.5B).

The average total number of DP nests in Greece for the period 1967-1977 was 110 (range 70-155 AON) and continuously increased subsequently, with an annual growth rate of ca 7.9% (n=38 years, 1983-2021) (Fig. 5C).

## DISCUSSION

### Data quality

Despite probable variability owing to different cen- sus methods and different observers, census results can be used for an overall analysis such as in this paper. This claim can be justified by the fact that: a. the adopted meth- ods were based on common guidelines developed by the IPRCP in the 1980s (Crivelli 1987); b. the objectives of study did not change to a degree that undermined the val- ue of the survey (Magurran et al. 2010); c. the straight- forward nature of the surveyed objects (number of AON during the breeding period) and d. the same experienced researcher trained all other observers in all methods.

The shift in census methodology, basically the introduction of drone use, might be a source of bias mainly for the Prespa population, for which vantage-point surveys in the period 2000-2013 might have slightly underestimated
<figure><img src="image_5.png" /></figure>

**Figure 2:** Aerial and ground images of the pelican colonies in Greece: (1) Prespa, natural islets, (2) Prespa, close up of the mixed colony; (3) Cheimaditis; (4) Karla, the old nesting island; (5) Karla, the current artificial island; (6) Karla, aspect of the boulder island with nesting pelicans; (7) Kerkini, the artificial island; (8) Kerkini, the wooden raised platform; (9) Amvrakikos natural islands; (10 &12) Messolonghi, natural islands; (11) Messolonghi, sub-colony on old disused road. Photo credits: 1,3,4,7/ O. Alexandrou-SPP Archive, 2/ F. Marquez-The Living Med, 5/ D. Michalakis-N.E.C.C.A., 6/ R. Papadopoulou, 8/ Th. Naziridis-N.E.C.C.A. 9/ S. Konstas-N.E.C.C.A., 10-12/ I. Kasvikis-N.E.C.C.A.
total population size, due to varying visibility between
sub-colonies. Differences were minimised due to the
experience of the principal observer, who has been the
same over the years. A similar shift also took place at
Karla and Messolonghi, but colony sizes in these locations
are small and discrepancies between results obtained by
the two methods are thus also considered to be very small.

Population growth and trends

*Prespa:* Besides the intrinsic growth potential of the Prespa population, growth might have been affected by a spatial expansion of the nesting area, which was made possible in 1990 due to management measures, as well as the stochastic formation of two very large nesting islands, which might have enhanced social stimulation through higher breeding densities (Catsadorakis & Crivelli 2001). In the last ten years, population growth seems to have lev- elled off, egg and chick mortality has increased, and breed- ing success declined, something commonly observed in colonies at a similar stage (Newton 1998). Laying initia- tion has advanced (Doxa et al. 2012a) and is still advanc- ing (G. Catsadorakis & O. Alexandrou, unpublished data), late winter-early spring adverse weather events affect BS negatively and re-laying seems to have been a common phenomenon during the last 8 years. In years of extreme drought many nesting islands become accessible by land, limiting available nesting habitat, so the breeding popu- lation declines. At the other extreme, in very wet years parts of nesting islands are flooded and become unavail- able to pelicans (Catsadorakis et al. 1996). Furthermore, the Prespa lakes are the highest-lying large lakes in the Balkans and although they also offer an abundance of fish, these are not available to the birds in January to March. The water level of Lake Megali Prespa, the main feeding ground for pelicans, has suffered a 9 m drop and this might have changed the availability of fish. In the last 30 years, due to the dramatic advancement of laying (Doxa et al. 2012a), many DPs start breeding when it seems no prey is available in these lakes. A mismatch is thus created due to the inverse relationship between laying initiation date and food availability, which may be the main reason for the failure of early breeders. In the past, DP nesting early in Prespa had to visit the lower-lying Lake Kastoria to feed (Crivelli 1987; Hatzilacou 1992), but in recent years they have been obliged to travel even farther to find food, as far as Lake Kerkini (Efrat et al. 2018; Georgopoulou et al. 2023) which lies ca 200 kms away.

Kerkini: The number of breeding pairs is limited by
the space available on the artificial nesting platforms de-
pending on management decisions. Shortage of nesting
space was clearly demonstrated after increases in platform
area (Figs 2.7, 2.8) led to increases in breeding pairs. Fur-
thermore, hydrological manipulations determine water
level during January-February when nest-building starts,
and this in turn determines how many nests will be built

on the artificial islet. If the area around it is not yet flooded,
pelicans delay nest initiation and the final number of nests
is low.

Karla: Initially increasing nest numbers dropped when rising water levels forced birds to abandon the first occupied site for a new, higher-lying colony island, but they have started to increase again. Thus, it makes no sense to discuss the growth rate of this colony separate- ly. Furthermore, between 2016 and 2019, 247 DPs died in Karla, with the probable mortality attributed to cyanotox- ins (Papadimitriou et al. 2018). The timing of deaths coinc- ided with the shift in colony site, so no conclusions can be drawn from the confounding effect of these two variables on the population size, which nevertheless did not seem to directly affect the site’s attractiveness for breeding.

*Cheimaditis:* Only five years of data are not enough to discuss the growth pattern of this newest of colonies to any great extent. In the last three years it seems there has been a stability in nest numbers, but the BS remains low, in some years due to disturbance by fishermen and in 2021 by H5N8-caused mortality (G. Catsadorakis & O. Alexan- drou, unpublished data).

*Amvrakikos:* Because the two groups of nesting is-
lands are c. 9 km apart, we can refer to the presence of
two colonies in this site. Since the 1980s many nesting
islands have eroded away, whilst the existing ones suffer
from erosion associated with limited sediment inputs, ris-
ing lagoon water levels and wave action, noted by Crivelli
(1987) and Hatzilacou (1993). Nesting islets are visible
from all around and are easily accessible by boat. In the
1980s disturbance by fishermen, visitors, and fish- and
wildfowl poachers was frequent, hence the Hellenic Or-
nithological Society carried out a volunteer guarding
project (1985-1990, taking place for four months annual-
ly. During the IPRCP (1985 to 2009), the increase of the
breeding population can be possibly associated with reg-
ular surveying of the colonies and successful sensitisation
and awareness actions. However, the colonies suffered
from disturbance in 2009 and 2010, which coincided with
the termination of the IPRCP study (D. Hatzilacou, unpub-
lished data). After 2016, patrolling by the national park
management body improved, acceptance of pelicans by
fishermen increased and disturbance declined, which may
have allowed pelicans’ breeding success to improve and
numbers to increase, however this seems to have levelled
off at around 150 pairs.

*Messolonghi:* The >30% annual growth rate of the Messolonghi colony is a strong indication that this new colony continues to receive immigrants from the Amvraki-kos colonies. After the disturbance event of 2018, pelicans colonised more islands in the Kentriki lagoon, so that two separate colonies were formed 12 km apart. The breeding population is still on the increase and the Kentriki colony in particular seems to have a huge potential for increase.
<table><caption>**Table 2:** Basic descriptive features and attributes of the Dalmatian pelican colony sites in Greece</caption><thead><tr><th>ATTRIBUTES</th><th>PRESPA</th><th>KERKINI</th><th>KARLA</th><th>CHEIMADITIS</th><th>AMVRAKIKOS</th><th>MESSOLONGHI</th></tr></thead><tbody><tr><td>Date of colony establishment</td><td>&lt;1936</td><td>2002</td><td>2011</td><td>ca 2015</td><td>mid-19th c.</td><td>1677-1940s/ 2011-</td></tr><tr><td>Number of frequently occupied discrete islands</td><td>&gt;30</td><td>1--3</td><td>2</td><td>3--5</td><td>3--4</td><td>5--7</td></tr><tr><td>Number of discrete colonies (concentrations &gt;3km apart)</td><td>1--2</td><td>1</td><td>1</td><td>1</td><td>2</td><td>2</td></tr><tr><td>Type of nesting islands /natural/artificial/other</td><td>Natural</td><td>Artificial</td><td>Artificial / Other</td><td>Natural</td><td>Natural</td><td>Natural/Other</td></tr><tr><td>Type of substrate of nesting islands</td><td>Reed rhizomes</td><td>Wooden platforms/ Rocks</td><td>Gravel/ Rocks</td><td>Reed rhizomes</td><td>Sandy</td><td>Sandy / Gravel</td></tr><tr><td>Vegetation cover/ plant species</td><td>Reeds & other aquatic macrophytes</td><td>None</td><td>Nitrophiles</td><td>Reeds & other aquatic macrophytes</td><td>Salicornia, Athrocennemum</td><td>Salicornia, Athrocennemus / none</td></tr><tr><td>Western population group / Eastern population group</td><td>E</td><td>E</td><td>E</td><td>E</td><td>W</td><td>W</td></tr><tr><td>Type of water body</td><td>Lake</td><td>Dammed river/Reservoir</td><td>Reservoir</td><td>Lake</td><td>Lagoons</td><td>Lagoons</td></tr><tr><td>Purposeful disturbance occurrence*</td><td>Low</td><td>Low</td><td>Low</td><td>Some</td><td>High</td><td>Medium</td></tr><tr><td>Unintentional, side-effect disturbance occurrence</td><td>Low</td><td>Some</td><td>Low</td><td>Some</td><td>High</td><td>High</td></tr><tr><td>Colony island erosion</td><td>Some</td><td>Some</td><td>Some</td><td>Some</td><td>Medium</td><td>Medium</td></tr><tr><td>Suspected limitation by nesting space</td><td>High</td><td>High</td><td>Medium</td><td>Low</td><td>Low</td><td>Low</td></tr><tr><td>Suspected limitation in access to food</td><td>Low</td><td>Low</td><td>Some</td><td>Low</td><td>Medium</td><td>Medium</td></tr><tr><td>Suspected occurrence of competition for food</td><td>High</td><td>High</td><td>Some</td><td>Medium</td><td>Low</td><td>Low</td></tr><tr><td>Suspected/ indications for competition for nesting space</td><td>High</td><td>Low</td><td>Some</td><td>Some</td><td>Low</td><td>Low</td></tr><tr><td>Disturbance at feeding areas</td><td>Low</td><td>Some</td><td>Low</td><td>Some</td><td>Medium</td><td>Medium</td></tr><tr><td>Frequent mortality causes</td><td>N/A</td><td>N/A</td><td>Toxins</td><td>N/A</td><td>Collisions</td><td>Collisions</td></tr><tr><td>Maximum distance between most distant nests of same colony (m)</td><td>2,150</td><td>150</td><td>45</td><td>950</td><td>330</td><td>1,600</td></tr><tr><td>Area covered by Minimum Convex Polygon of all nesting islands, Km²)</td><td>0.1/0.1</td><td>&lt;0.1</td><td>&lt;0.1</td><td>&lt;0.1</td><td>&lt;0.1</td><td>1</td></tr><tr><td>Strong water level fluctuation</td><td>Low</td><td>High</td><td>Medium</td><td>Low</td><td>Some</td><td>Some</td></tr></tbody></table>

<footnote>*Threats according to Salafsky et al. 2008. Magnitude scale: Nil, Low, Some, Medium, High</footnote>
*Greece:* There is a consensus in the ornithological literature that most seabird populations are regulated, usually in a density-dependent way, and that important regulatory factors are food, breeding space, parasites and predation (Croxall & Rothery 1991). After 35 years of work with DPs in Greece there are no indications that parasites and predation do substantially affect breeding performance and/or numbers of these birds anywhere.

As regards prey abundance and availability, in Greece there are neither fish stock estimations (but see Bounas et al. 2021 for Prespa) nor adequate understanding of fish movement patterns in these shallow wetlands in relation to season, water temperature and light. Shallow Mediterranean lakes suffer from rapid eutrophication and, as such, fish stocks in lakes in northern Greece, which are dominated by cyprinids, have increased everywhere (Beklioğlu et al. 2007), but prey abundance is not always a good measure of food-supply when other factors limit its accessibility (Newton 1991). Kerkini, being the most productive lake in the region, has a key role in the wetlands network used by pelicans in northern Greece. It is used as the last staging site for pelicans migrating to Prespa, Cheimaditis and Karal to breed and it hosts pelicans all year round in contrast to the other three sites of the Eastern population group.

The increase of DP might possibly be attributed to: a. increased survival rates through reduced mortality owing to the milder climate in wintering grounds due to climate change (cf. Barboutis et al. 2021); b. higher fish availability due to the sustained activity allowed by higher mean winter temperatures (cf. also Lack 1968), also due to climate change; c. lower disturbance due to enhanced patrolling in protected areas; d. higher numbers of sympatrically nesting great cormorants that allow higher feeding efficiency (cf. Giokas et al. 2020); and e. less persecution by fishermen as a result of the shrinking size of commercial inland fisheries, similar to the marked increase of many seabirds in the North Sea during the 20th c., which had also been attributed to the relaxation of human persecution (Cramp et al. 1974). A rapid increase is the norm in new colonies (Newton 1998), as has been the case with Karla, Cheimaditis and Messolonghi, due to high net immigration rates.

## Formation of new colonies and patterns of human influence

The formation of new colonies is not a frequent phenomenon in seabirds (Coulson 2002). For at least 60 years (1940s-early 2000s) there were only two DP colonies in Greece. Starting from around 100 AON in the period 1967-1982, in 2002 (before the third colony at Kerkini appeared) the Greek breeding population had increased by c. 640%, but no new colonies were formed. In the next 20 years the population rose threefold and 4 new colonies were formed. This fact indicates that external factors were keeping pelican populations suppressed and when these factors relaxed

or were lifted, populations exploded, but it is likely that the processes for the creation of new colonies set off when the two “parent” colonies reached their maximum capacity in spatial terms and recruits could not be accommodated within them. Whether seabirds are indeed limited by nesting space and whether there is competition over it are both notoriously difficult to prove (Coulson 2002; Hamer et al. 2002). In the case of DPs in Greece, the creation of new colonies was made possible after suitable artificial nesting structures were offered to pelicans (Kerkini in 2002) and when a new wetland emerged (Karla in 2009) with a semi-natural nesting island that was free of disturbance (Catsadorakis 2019). The “natural experiments” described above, combined with the large intra-colony differences in breeding success in Prespa, are possible indications of a shortage of high-quality nesting sites. The relaxation of pressure from fishermen may also have contributed to allowing the initiation of new colonies at Messolonghi and Cheimaditis.

## CONSERVATION

Until the 1980s the two colonies at Prespa and Amvrakikos suffered from disturbance, mainly by fishermen and secondarily by wildlife photographers. Besides Prespa, where effective conservation measures in the 1980s and 1990s allowed the population to increase, conservation measures had been improving slowly everywhere in Greece and possibly also in Turkey’s main wintering wetlands.

The levelling-off which is observed in the two old colonies and the dynamic growth of the new colonies show that conservation measures should not be designed and decided for individual wetlands only but should consider the dynamic nature of the two population groups (meta-populations?). In the last twenty years a transitional phase has been observed with the creation of new colonies, but perhaps even more will be created soon, so monitoring of all pelican populations on an annual basis is required, as it will give quick and timely warnings for necessary measures.

During the 20th century many seabird species have increased greatly, in some places because of reduced human persecution and in others because human fishing activities have made their food more available (Newton 1998). The role of anthropogenic factors that strongly interact with natural factors, and are all assumed to have contributed to the pelican increase in Greece in the last 40 years, should not underemphasised: legal protection status for all pelican-hosting areas; increasingly effective protection and conservation measures in the field; public awareness campaigns; provision of artificial nesting structures; decrease of pollution; decline of disturbance and persecution due to relaxation of pressure by fishermen and decline of fisheries; appearance of new wetlands and alteration of wetlands due to human intervention.
<figure><img src="image_6.png" /><figcaption>**Figure 3:** The growth of AON numbers in each of the six colonies of Greece (1983-2021). For the Prespa and Amvrakikos colonies a cubic polynomial regression curve is fitted and shown. For all other colonies a bi-quadratic polynomial regression line is shown. Note the differences in scale.</figcaption></figure>
<figure><img src="image_7.png" /><figcaption>**Figure 4:** Boxplots showing the median (horizontal line) and interquartile range (box) of the breeding success (fledged young/pair) of Dalmatian pelican colonies in Greece, 2012-2021. \*=p<0.05, \*\*=p<0.01.</figcaption></figure>
<figure><img src="image_8.png" /></figure>

<figure><img src="image_9.png" /></figure>

<figure><img src="image_10.png" /><figcaption>**Figure 5:** The evolution of total Dalmatian pelican breeding population sizes (estimated as AON) in Greece 1983-2021. A. The Eastern population group, B. The Western population group and C. The whole of Greece. A cubic polynomial regression curve is shown for each.</figcaption></figure>
Disturbance-free nesting sites and reduced mortality
causes should be secured. Monitoring population trends
and especially BS in as standard a mode as possible is
crucial for evaluating conservation measures. An assumed
shortage of nesting space merits a closer examination to
shed light to the exact importance of its impact upon DPs,
as, not only are the physical attributes of the habitats in-
volved but the social mechanisms too (cf. Coulson 2002).
Further work should also be done to understand the pat-
terns of use the DPs make of all wetlands for foraging and
their feeding behaviour and efficiency.

Lastly, the movement corridors of these large soaring
birds when moving between wetlands should be located
and protected effectively, especially in view of the estab-
lishment of new wind parks on mountain slopes that are
heavily used by commuting pelicans (Efrat et al. 2018;
Georgopoulou et al. 2023).

ACKNOWLEDGEMENTS

The IPRCP was supported by the MAVA Foundation
and has greatly contributed to the improvement of the
conservation status of the species. Since 2010 the environ-
mental, non-governmental organisation the Society for the
Protection of Prespa (SPP) has continued co-ordination
work for pelicans in SE Europe. The work of the SPP on
pelicans was funded by MAVA until 2018 and after that by
the Prespa Ohrid Nature Trust (PONT). In 2015 a Mem-
orandum of Co-operation regarding the monitoring of
pelican populations in Greece, was signed by the Society
for the Protection of Prespa, the Hellenic Ornithological
Society and all the management bodies of protected ar-
eas hosting substantial numbers of DPs on a regular basis.
Since then, reports on the status of DPs at each of these
sites have been produced annually and a large part of the
data used in this document was included in those reports.
After 2021 all the management bodies for protected areas
in Greece were incorporated into the Natural Environment
& Climate Change Agency (N.E.C.C.A.), a legal entity su-
pervised by the Ministry of Environment and Energy.

This work uses data which could have never been
collected without the invaluable contribution of numerous
people who participated in the hundreds of field expedi-
tions necessary to survey pelican colonies throughout all
these years. An anonymous reviewer's comments im-
proved a first draft and Julia Henderson corrected the En-
glish of a revised draft of the article.

LITERATURE CITED

Barboutis, Ch., Kassara, Ch., Alexandrou, O. & Catsadorakis, G. (2021) Long-term changes in the wintering population of the Dalmatian Pelican along the Black Sea-Mediterranean Flyway. Ardea 109: https://doi.org/10.5253/arde.v109i3.a4

Beklioğlu, M., Romo, S., Kagalou, I., Quintana, X. & Bécares, E. (2007) State of the art in the functioning of shallow Mediterranean lakes: workshop conclusions. Hydrobiologia 584, 317–326, https://doi.org/10.1007/s10750-007-0577-x

BirdLife International (2021) Species factsheet: *Pelecanus crispus*, Retrieved from [http://datazone.birdlife.org/species/factsheet/dalmatian-pelican-pelecanus-crispus](http://datazone.birdlife.org/species/factsheet/dalmatian-pelican-pelecanus-crispus)

Bounas, A., Catsadorakis, G., Koutseri, I., Nikolaou, H., Nicolas, D., Malakou, M. et al. (2021) Temporal trends and determinants of fish biomass in two contrasting natural lake systems: insights from a spring long-term monitoring scheme. Knowl Manag Aquat Ec 422, 28 https://doi.org/10.1051/kmae/2021027.

Bounas, A., Catsadorakis, G., Naziridis, Th., Bino, T., Hatzilacou, D., Malakou, M. et al. (2022) Site fidelity and determinants of wintering decisions in the Dalmatian Pelican (*Pelecanus crispus*), a short-distance migratory waterbird. Ethol Ecol Evol https://doi.org/10.1080/03949370.2022.2094471

Catsadorakis, G. & Portolou, D. (compilers) (2018) International Single Species Action Plan the Conservation of the Dalmatian Pelican (*Pelecanus crispus*). CMS Technical Series No. 39, AEWA Technical Series No. 69, EAAFP Technical Report No. 1. Bonn, Germany and Incheon, South Korea. Retrieved from: https://www.unep-aewa.org/sites/default/files/document/aewa_stc13_17_draft_aewa_eu_issap dp.pdf

Catsadorakis, G. (2016) An update of the status of the two *Pelecanus* species in the Mediterranean-Black Sea region In: P. Jesou, J. Sultana, J. Walmsley & H. Azafzaf (Eds.), Conservation of marine and coastal birds in the Mediterranean. Proceedings of the UN-EP-MAP, RAC/SPA Symposium (20-22 February 2015, Hammamet, Tunisia), 47-53.

Catsadorakis, G. (2019) Establishment and growth of a new Dalmatian Pelican Pelecanus crispus colony in Central Greece. Acta Ornithol 54, 125–132. https://doi.org/10.3161/00016454AO2019.54.1.010

Catsadorakis, G. & Crivelli, A.J. (2001) Nesting Habitat Characteristics and Breeding Performance of Dalmatian Pelicans in Lake Mikri Prespa, NW Greece. Waterbirds 24, 386-393. https://doi.org/10.2307/1522069

Catsadorakis, G., Malakou, M. & Crivelli, A.J. (1996) The effects of the 1989/1990 drought on the colonial waterbirds nesting at Lake Mikri Prespa, Greece, with special emphasis on pelicans. Colon Waterbird 19, 207-218. https://doi.org/10.2307/1521964

Catsadorakis, G., Onmuş, O., Bugariu, S., Gül, O., Hatzilacou, D., Hatzofe, O. et al. (2015) Current status of the Dalmatian Pelican and the Great White Pelican in the Black Sea / Mediterranean flyway. Endange Species Res 27, 119-130. https://doi.org/10.3354/esr00659
Cody, M.L. & Smallwood, J.A. (Eds.) (1996) Long-term studies of vertebrate communities. San Diego: Academic Press.

Collins, S.L. (2001) Long term research and the dynamics of bird populations and communities. Auk 118, 583-588. https://doi.org/10.1093/auk/118.3.583

Coulson, J.C. (2002) Colonial breeding in seabirds. In: E.A. Schreiber & J. Burger (Eds.), Biology of marine birds (pp. 87-113), Boca Raton, Cal.: CRC Press.

Cramp, S., Bourne, W.R.P. & Saunders, D. (1974) The seabirds of Britain and Ireland. London: Collins.

Crees, J.J., Oxley, V.A. Schreve, D.S. & Turvey, S.T. (2022) Challenges for incorporating long-term baselines into biodiversity restoration: A case study of the Dalmatian Pelican (*Pelecanus crispus*) in Britain. Ibis. https://doi.org/10.1111/ibi.13154

Crivelli, A.J. (1983) European pelican populations and their conservation. In: P.R. Evans, H. Hafner & P. L' Hermite (Eds.), Proceedings of two workshops "Shorebirds and large waterbirds conservation" (St Aidan's College, Durham, Sept.17-18, 1983), (pp. 123-128). Brussels: Commission of the European Communities.

Crivelli, A.J. (1987) The ecology and behaviour of the Dalmatian pelican, *Pelecanus crispus* Bruch 1832, a world-endangered species. Final report on Contract ENV-834-F (MR). Commission of the European Communities and Biological Station of La Tour du Valat.

Crivelli, A.J. (1990) Fisheries decline in the freshwater lakes of northern Greece with special attention for Lake Mikri Prespa. In: W.L.T. van Densen, B. Steinmetz & R.H. Hughes (Eds.), Proceedings of a symposium of European Inland Fisheries Advisory Commission, (Göteborg, Sweden, 31/5-3/6 1988), Wageningen; PUDOC-III, 230-247.

Crivelli, A.J. (1994) The importance of the former USSR for the conservation of pelican populations nesting in the Palearctic. In: A.J. Crivelli, V.G., Krivenko & V.G., Vinogradov (Eds.) Pelicans in the former USSR. IWRB Special Publication No. 27, 1-4.

Crivelli, A.J. (Compiler) (1996) Action Plan for the Dalmatian pelican (*Pelecanus crispus*) in Europe. Cambridge: BirdLife International.

Crivelli, A.J., Catsadorakis, G. & Naziridis, Th. (1997) *Pelecanus crispus* Dalmatian Pelican. Bird West Pal Update 1, 149-153.

Crivelli, A.J., Catsadorakis, G., Jerrentrup, H., Hatzilacou, D. & Michev, T. (1991) Conservation and management of pelicans nesting in the Palearctic. ICBP Technical Publication No 12, 137-152.

Crivelli, A.J., Catsadorakis, G., Hatzilacou, D., Hulea, D., Malakou, M., Marinov, M. et al. (2000) Status and population development of Great White and Dalmatian pelicans, *Pelecanus onocrotalus* and *P. crispus* breeding in the Palearctic. In: P. Yésou & J. Sultana

(Eds.) Proceedings of the 5th Medmaravis Symposium, (29 September-3 October 1998, Gozo, Malta), 38-45.

Crivelli, A.J., Grillas, P., Jerrentrup, H. & Naziridis, Th. (1995a) Effects on fisheries and waterbirds of raising water levels at Kerkini Reservoir, a Ramsar Site in Northern Greece. Environ Manage 19: 431-443. https://doi.org/10.1007/BF02471984

Crivelli, A.J., Hatzilacou, D. & Catsadorakis, G. (1998) The breeding biology of the Dalmatian Pelican *Pelecanus crispus*. Ibis 140, 472-481. https://doi.org/10.1111/j.1474-919X.1998.tb04609.x

Crivelli, A.J., Jerrentrup, H. & Mitchev, T. (1988) Electric Power Lines: A Cause of Mortality in *Pelecanus crispus* Bruch, a World Endangered Bird Species, in Porto-Lago, Greece. Colon Waterbird 11, 301-305. https://doi.org/10.2307/1521012

Crivelli, A.J. & Schreiber, R.W. (1984) Status of the Pelcanidae. Biol Conserv 30, 147-156. https://doi.org/10.1016/0006-3207(84)90063-6

Crivelli, A.J. & Vizi, O. (1981) The Dalmatian pelican *Pelecanus crispus* Bruch 1832, a recently world endangered bird species. Biol Conserv 20, 297-310. https://doi.org/10.1016/0006-3207(81)90016-1

Croxall, J.P. & Rothery, P. (1991) Population regulation of seabirds: implications of their demography and conservation. In: C.M. Perrins, J-D. Lebreton, & G.J.M. Hirons (Eds.), Bird Population Studies: relevance to conservation and management (pp. 272-296). Oxford: Oxford University Press.

Deinet, S., Ieronymidou, C., McRae, L., Burfield, I.J., Foppen, R.P., Collen, B. et al. (2013) Wildlife comeback in Europe: The recovery of selected mammal and bird species. Final report to Rewilding Europe by Zoological Society London, BirdLife International and the European Bird Census Council. London. Retrieved from: https://policycommons.net/artifacts/2677362/download-2013/3700562/

Doxa, A., K. Theodorou, AJ Crivelli, D. Hatzilacou, G Catsadorakis, M. Malakou, et al. (2012a) Spatially correlated environmental factors drive synchronization in populations of Dalmatian pelican. Popul Ecol 54, 499-507. https://doi.org/10.1007/s10144-012-0330-9

Doxa, A., Robert, A., Crivelli, A.J., Catsadorakis, G., Naziridis, Th., Nikolaou, H. et al. (2012b) Shifts in breeding phenology as a response to population size and climatic change: A comparison between short- and long-distance migrant species. Auk, 129, 753-762. https://doi.org/10.1525/auk.2012.11213

Doxa, A., Theodorou, K., Hatzilacou, D., Crivelli, A.J., Robert, A. (2010) Joint effects of density-dependence and extreme environmental variation on theviability of a social bird species. EcoScience, 17, 203-215. https://doi.org/10.2980/17-2-3304
Efrat, R., Harel, R., Alexandrou, O., Catsadorakis, G., Na-
than, R. (2018) Seasonal differences in energy expen-
diture, flight characteristics and spatial utilization of
Dalmatian Pelicans *Pelecanus crispus* in Greece. Ibis
https://doi.org/10.1111/ibi.12628

Erwin, R.M. (2002) Integrated management of waterbirds: Beyond the conventional. Waterbirds 25(SP), 5-12.
https://www.jstor.org/stable/1522447

Franklin, J.F. (1989) Importance and Justification of Long-
Term Studies in Ecology. In: Likens, G.E. (eds) Long-
Term Studies in Ecology. New York: Springer. https://
doi.org/10.1007/978-1-4615-7358-6 1

Georgopoulou, E., Alexandrou, O., Manolopoulos, A.,
Xirouchakis, S. & Catsadorakis, G. (2023) Home
range of the Dalmatian pelican in south-east Europe.
Eur J Wildlife Res 69, 41 https://doi.org/10.1007/
s10344-023-01667-1

Giokas, S., Maximiadi, M., Kassara, Ch., O. Alexandrou, O. & Catsadorakis, G. (2020) Mixed-species flock fishing in Dalmatian Pelicans: patterns and benefits. Ardea, 108, 65–72. https://doi.org/10.5253/arde.
v108i1.a9

Gkelis, S., Panou, M., Chronis, I., Zervou, S-K., Christo-
phoridis, Ch., Manolidi, K. et al. (2017) Monitoring a
newly re-born patient: water quality and cyanotoxin
occurrence in a reconstructed shallow Mediterranean
lake. Adv Oceanogr Limnol 8, 33–51. https://doi.
org/10.4081/aiol.2017.6350

Grace, M.K., Akçakaya, H.R., Bennett, E.L., Brooks, T.M., Heath, A., Hedges, S. et al. (2021) Testing a global standard for quantifying species recovery and assessing conservation impact. Conserv Biol 35, 1833–1849. https://doi.org/10.1111/cobi.13756

Hamer, K.C., Schreiber E.A. & Burger, J. (2002) Breeding biology, life histories and life history-environment interactions in seabirds. In: EA Schreiber & J Burger (eds) Biology of Marine Birds. CRC Marine Biology Serie (pp. 217-262). Boca Raton: CRC Press.

Handrinos, G., Kazantzidis, S., Alivizatos, Ch. & Port-
olou, D. (2015) International Waterbird Census in
Greece (1968-2006). Analysis of populations of wild-
fowl (Anseriformes) and the Coot (Fulica atra). Ath-
ens: Hellenic Ornithological Society-Hellenic Bird
Ringing Centre.

Hatzilacou, D. (1992) The breeding biology and feeding ecology of the Great White Pelican *Pelecanus onocrotalus* L.1758, at Lake Mikri Prespa (Northwestern Greece). PhD dissertation. National & Kapodestrian University of Athens (in Greek with English summary). doi: 10.13140 / RG. 2.1.1467.7200

Hatzilacou, D. (1993) The distribution of the globally en-
dangered Dalmatian pelican in Greece. Threats per-
taining to its habitats and recommendations for pro-
tection. Unpublished study. RSPB, BirdLife-UK. 220
pp.

Hotos, G.N. & Katselis, G. (2011) Age and growth of the Golden Grey Mullet *Liza aurata* (Actinopterygii, Mugiliformes: Mugilidae) in the Messolonghi-Etoliko Lagoon and the adjacent Gulf of Patraikos, Western Greece. Acta Ichthyol Piscat 41, 147-157. https://doi.org/10.3750/AIP2011.41.3.01

Johnston, G.R. (2016) Breeding biology of Australian Pelicans *Pelecanus conspicillatus* on the coast of South Australia. Waterbirds 39, 300–305. https://doi.org/10.1675/063.039.0310

Katselis, G.N., Moutopoulos, D.K., Dimitriou, E.N. & Koutsikopoulos, C. (2013) Long-term changes of fisheries landings in enclosed gulf lagoons (Amvrakikos Gulf, W Greece): Influences of fishing and other human impacts. Estuar Coast Shelf S 131, 31-40. https://doi.org/10.1016/j.ecss.2013.07.004

Knopf, F.L. (1979) Spatial and temporal aspects of colonial nesting pelicans. Condor, 81, 353–363. https://doi.org/10.2307/1366959

Kurstjens, G., van Turnhout, C., de Leeuw, J. & Spanoghe, G. (2021) Kansen kroeskoppelikaan in Nederland en Vlaanderen. Kurstjens, Ecologisch adviesbureau, Sovon Vogelonderzoek Nederland, Wageningen University & Research and Instituut voor Natuur- en Bosonderzoek. Retrieved from https://www.iucn.nl/app/uploads/2021/10/Kroeskoppelikaan-onderzoek_definitief.pdf

Lack, D. (1968) Population Studies of Birds. Oxford: Clarendon Press.

Magurran, A.E., Baillie, S.R., Buckland, S.T., Dick, J.McP., Elston, D.A., Marian Scott, E. et al. (2010) Long-term datasets in biodiversity research and monitoring: assessing change in ecological communities through time. Trends Ecol Evol https://doi.org/10.1016/j.tree.2010.06.016

Newton, I. (1991) Population limitation in birds of prey: a comparative approach. In: C.M. Perrins, J-D. Lebreton & G.J.M. Hirons (Eds.), Bird Population Studies: relevance to conservation and management (pp. 3-21). Oxford: Oxford University Press.

Newton, I. (1998) Population limitation in birds. San Díego, Cal : Academic Press.

Oikonomou, A., M., Karayanni, H., Moustaka-Gouni M. & Kormas, K.A. (2012) Plankton microorganisms coinciding with two consecutive mass fish kills in a newly reconstructed lake. Sci World J https://doi.org/10.1100/2012/504135

Papadimitriou, Th., Katsiapi, M., Vlachopoulos, K., Christopoulos, A., Laspidou, Ch., Moustaka-Gouni M., et al. (2018) Cyanotoxins as the “common suspects” for the Dalmatian pelican *Pelecanus crispus* deaths in a Mediterranean reconstructed reservoir. Environ Pollut 234, 779–787. https://doi.org/10.1016/j.en-vpol.2017.12.022
Pergantis, F. & Handrinos, G. (1992) A preliminary check-
list of the birds of the Messolonghi wetlands (1860–
1986) with seasonal occurrence and population data.
Biol Gallo-Hellen 19, 89–112.

Petriki, O. (2015) Development of a fish based multi-met-
ric index for the assessment of the ecological quality
of Greek lakes. PhD thesis, Aristotle University of
Thessaloniki, Thessaloniki, Greece (in Greek with
English summary). Retrieved from: https://thesis.ekt.
gr/thesisBookReader/id/37207#page/1/mode/2up

Petriki, O. & Bobori, D. (2009) Fish species composition and abundance in Kerkini reservoir. In: Proceedings, 9th Symposium on Oceanography & Fisheries, (2009) Volume II, 1206-1211.

Pyrovetsi, M. & Crivelli, A.J. (1988) Habitat Use by Waterbirds in Prespa National Park, Greece. Biol Conserv 45, 135-153. https://doi.org/10.1016/0006-3207(88)90044-4

Reif, J. (2013) Long-term trends in bird populations: a re-
view of patterns and potential drivers in North Amer-
ica and Europe. Acta Ornithol 48, 1-16. https://doi.
org/10.3161/000164513X669955

Roussopoulos, I. (2012) Monitoring the populations of four protected avian species in the wider area of Messolonghi and the lower Achelloos river in 2012: Dalmatian pelican, white stork, lesser kestrel, and griffon vulture. Self-published report, 48 p. (In Greek).

Salafsky, N., Salzer, D., Statterfield, A.J., Hilton-Taylor, C., Neugarten, R., Butchart, S.H.M. et al. (2008) A standard lexicon for biodiversity conservation: uni-

fied classifications of threats and actions. Conserv
Biol 22, 897–911. https://doi.org/10.1111/j.1523-1739.2008.00937.x

Strayer, D.J., Glitzenstein, S., Jones, C.G., Kolasa, J., Lik-
ens, G.E., McDonnell, M.J. et al. (1986) Long-term
ecological studies: an illustrated account of their de-
sign, operation, and importance to ecology. Institute
of Ecosystem Studies Occasional Publications 1.

Tatarakis, E. (1995) Fishery management of Lake Kerkini. In: K. Skordas & M. Anagnostopoulou (Eds.), Sustainable management of the water of Lake Kerkini. Proceedings of a training course (Serres, 25-29 September 1995). Thessaloniki: Greek Biotope/Wetland Centre - Ministry of Environment and Public Works - MedWet (in Greek).

Tsolakos, K., Katselis, G. & Theodorou, J.A. (2020) Taxonomy of mass mollusc shell accumulation at Amvrakikos Gulf lagoon complex sandy barriers (NW Greece). Oceanologia, 63, 179-193. https://doi.org/10.1016/j.oceano.2020.11.004

Wooler, R.D., Bradley, J.S. & Croxall, J.P. (1992) Long-term population studies of seabirds. Trends Ecol Evol 7, 111-114. https://doi.org/10.1016/0169-5347(92)90143-Y

Zalidis, C.G. & Mantzavelas, A.L. (Eds.) (1994) Inventory on Greek wetlands as natural resources. Thessaloniki: Greek Biotope/Wetland Centre.
SUPPLEMENTARY MATERIAL

<table><caption>Table S1: The environment and history of pelican colonies in Greece</caption><thead><tr><th></th><th></th></tr></thead><tbody><tr><td>Lakes Mikri and Megali Prespa</td><td>The two mixed DP and great white pelican <i>Pelecanus onocrotalus</i> colonies, which lie ca 13.5 km apart were discovered in 1968 (Brosselin & Molinier 1968) and were: a. In the unused area in Lake Mikri Prespa, around the Greek-Albanian border, but which was abandoned in 1991; and b. In the inland Viro-1 pond, lying in the alluvial zone separating the two lakes. There are indications they had existed there since at least the early 20<sup>th</sup> c. (Handrinos & Catsadorakis 2020). For the period 1968-1982 there are scattered and incomplete estimations of AON for 11 of the 15 years (Crivelli 1980), ranging from 40 to 150 (average 89). A 3-year drought (1988-1990) excluded pelicans from their two traditional breeding grounds, which became accessible by terrestrial predators (Catsadorakis et al. 1996), but in 1990 they were finally forced to nest on artificial islands. Conservationists convinced local fishermen to “concede” a part of the open lake to pelicans for nesting (i.e. without approaching them during the breeding period). This allowed pelicans to use this new area at the NNW part of Mikri Prespa, which had been previously unavailable because of the daily presence of fishermen. The expansion allowed further increases in the nesting population.</td></tr><tr><td>Lake Cheimaditis</td><td>After the raising of dykes in 2012, water level fluctuates little, around 591.5 m asl. There are only a few fishermen in this cyprinid-dominated lake. It is a wetland long known to be used by both species of pelicans for staging, roosting and foraging, particularly during spring (Pyrovetsi 1990, Hatzilacou 1992, 1993, 1996). The colony in this lake was discovered in 2017 but may have initiated 1-3 years earlier and had remained undetected (Handrinos & Catsadorakis 2020).</td></tr><tr><td>Lake Kerkini</td><td>A reservoir created by damming the River Strymon in 1932 for irrigation and flood control purposes. In 1982 a bigger dam and higher dykes increased its storage capacity. Colonies of 11 large waterbird species lie in the riparian forest, mainly of willows <i>Salix</i> sp., which is flooded during the breeding period (Crivelli et al. 1995; Naziridis & Papageorgiou 1996). Although pelicans were abundant in Kerkini all year round since at least the 1980s, the dramatic increase of water level in spring precludes pelican nesting, as all natural islands are flooded. It was only in May 1990 that pelicans attempted to breed on a natural island (13-15 nests with eggs, Pyrovetsi 1997), as well as on flooded trees (2 nests, Crivelli & Naziridis, unpublished data). In subsequent years 5-15 nests were made almost annually but were flooded. In 2002 a small, raised platform was built but not used and 52 nests were made but were also flooded. The following summer (2003) the raised platform area was doubled and DP nested (7 nests) but could not rear any young to fledging, something which finally took place in 2004 (Crivelli & Naziridis unpublished data, Handrinos & Catsadorakis 2020) and continues to date.</td></tr><tr><td>Karla Reservoir</td><td>Karla was a natural, floodplain lake in Thessaly, but was drained in 1962 to provide arable land and minimise flood impacts. The reservoir receives water from the River Pinios (35 km straight-line distance NW of Karla) and surface runoff from the surrounding catchment (Sidiropoulos et al. 2012). Dathe & Proft (1939) and Geroudet (1962) mentioned the presence of both DP and GWP in the old Lake Karla but offered no evidence of breeding. Catsadorakis (2019) discussed the establishment and growth of the DP colony in the reservoir, which started with one pair in 2011 and reached 445 AON in 2017. However, in 2018 increasing water levels led to partial flooding of the nesting island, while in 2019 it became fully submerged and pelicans shifted to an artificial island (c. 85m X 55 m) constructed of rocks, specifically for waterbird nesting. The number of nests dropped to 82 but increased in the following years. The initial nesting island was a mound of unused gravel, part of an old dyke, that protruded above the water surface. Initially it had been entirely bare, but gradually aquatic macrophytes developed on the island's margins.</td></tr><tr><td>Amvrakikos Gulf</td><td>The Arachthos and Louros rivers discharge into the Amvrakikos gulf. Tsoukalio (28.3 km<sup>2</sup>) and Logarou (35.0 km<sup>2</sup>) are the largest lagoons. One or more DP colonies had existed in Amvrakikos since at least the mid-19<sup>th</sup> century (Crivelli 1980). In 1967 a colony was discovered in the Rodia lagoon but in the early 1970s it was exterminated by fishermen, to show up again in 1979, in Tsoukalio lagoon this time (Hatzilacou 1992). For the period 1967-1977 there are estimations of the breeding population only for 7 years and AON averaged c. 21 (range 15-35). From 1987 to date the birds have nested on both Tsoukalio and Logarou lagoons. Their nests lie on flat, sandy islets covered with halophytic vegetation of <i>Salicornia europaea</i> and <i>Arthrocnemum macrostachyum</i> (Hatzilacou 1993, D. Hatzilacou & AJ Crivelli, presented at the 1st Meeting of Pelican specialists, Pyli, Prespa, Greece, 1-2 May 2012, Iliadou et al. 2014).</td></tr><tr><td>Messolonghi wetlands</td><td>The Messolonghi wetland complex was formed at the mouths of the Acheloos and Evinos rivers. The abundant presence of pelicans in Messolonghi has been documented since 1675 (Spon & Wheler 1679) and later from various sources in the mid-19<sup>th</sup> century (Handrinos & Catsadorakis 2020), while they still bred there until the 1940s (Roussopoulos 2012). They resumed breeding in 2011 (Handrinos & Catsadorakis 2020). Some of their nesting islands are relics of dykes built in the mid-20<sup>th</sup> c. as part of works for improving the lagoon's productivity for fisheries. Other nesting islets are low and flat, formed of sand and seashells with halophytic vegetation of <i>Salicornia</i> and <i>Arthrocnemum</i>. Initially pelicans nested only on 4-5 islets in the Western Kleisova lagoon, but in 2018, after a serious disturbance, they expanded to natural islands in the Kentriki lagoon. The two concentrations are over 10km apart and they constitute two rather separate colonies. Pelicans started with 6-8 nests in 2011 (Roussopoulos 2012), but in 2021 they had exceeded 180 AON in 19 breeding units on 8 different islets. Despite regular patrolling, disturbance events by visitors and wildfowl-poachers are not averted. Disturbance is probably often also caused by fishermen, who attempt to scare away great cormorants.</td></tr></tbody></table>
**Table S3 references**

Brosselin, M. & Molinier, A. (1968) Visite au lac de Mikra Prespa (Grèce). Bureau MAR, duplicated report, 20 pp.

Catsadorakis, G. (2019) Establishment and growth of a new Dalmatian Pelican *Pelecanus crispus* colony in Central Greece. Acta Ornithol 54, 125–132. https://doi.org/10.3161/00016454AO2019.54.1.010

Catsadorakis, G., Malakou, M. & Crivelli, A.J. (1996) The effects of the 1989/1990 drought on the colonial waterbirds nesting at Lake Mikri Prespa, Greece, with special emphasis on pelicans. Colon Waterbird 19, 207–218. https://doi.org/10.2307/1521964

Crivelli, A.J. (1980) The importance of Greece for the conservation of two species of pelicans: *Pelecanus onocrotalus* L. 1758 and *Pelecanus crispus* Bruch 1832. Nature-Newslet Hellen Soc Prot Nat 23/24, 36–39.

Crivelli, A.J., Grillas, P. & Lacaze, B. (1995b) Response of vegetation to a rise in water level at the Kerkini reservoir (1982-1991), a Ramsar site in Northern Greece. Environ Manage 19, 417–430. https://doi.org/10.1007/BF02471983

Dathe, H. & Proft, J. (1939) Zum Vorkommen der Pelikane in Griechenland. Ornithol Monatsber 47, 150–151.

Geroudet, P. (1962) Notes d'ornithologie Grecque: le lac Karla. Nos Oiseaux, 26, 303-312.

Handrinos, G. & Catsadorakis, G. (2020) The historical and current distribution of Dalmatian Pelican *Pelecanus crispus* and Great White Pelican *Pelecanus onocrotalus* in Greece and adjacent areas 1830-2019. Avocetta, 44, 11-20. https://doi.org/10.30456/AVO.2020105

Hatzilacou, D. (1992) The breeding biology and feeding ecology of the Great White Pelican *Pelecanus onocrotalus* L.1758, at Lake Mikri Prespa (Northwestern Greece). PhD dissertation. National & Kapodestrian University of Athens (in Greek with English summary). doi: 10.13140 / RG. 2.1.1467.7200

Hatzilacou, D. (1993) The distribution of the globally endangered Dalmatian pelican in Greece. Threats pertaining to its habitats and recommendations for protection. Unpublished study. RSPB, BirdLife-UK. 220 pp.

Hatzilacou, D. (1996) The feeding ecology of the Great White pelican *Pelecanus onocrotalus* nesting at lake Mikra Prespa (Northwestern Greece). Colon Waterbird 19, (Special Publication 1), 190-206. https://doi.org/10.2307/1521963

Iliadou, E., Panitsa, M., Raus, Th. & Dimopoulos, P. (2014) Flora and factors affecting species diversity in the islet groups of the protected “Natura 2000” sites of the Amvrakikos Gulf and Messolonghi Lagoon (Ionian area, Greece). Willdenowia 44, 439-450. https://www.jstor.org/stable/24750939

Naziridis, Th. & Papageorgiou, N. (1996) The breeding biology of Pygmy cormorants (*Phalacrocorax pygmeus*), a vulnerable bird species, at lake Kerkini, northern Greece. Colon Waterbird 19 (Special Publication 1), 219-223. https://doi.org/10.2307/1521965

Pyrovetsi, M. (1990) Conservation and management of the biotopes of the Dalmatian pelican (*Pelecanus crispus*) in northern Greece. Commission of the European Communities (DGXI) and Aristotle University of Thessaloniki, Thessaloniki, Greece, 145 pp.

Pyrovetsi, M. (1997) Integrated Management to Create New Breeding Habitat for Dalmatian Pelicans (*Pelecanus crispus*) in Greece. Environ Manage 21, 657–667. https://doi.org/10.1007/s002679900058

Roussopoulos, I. (2012) Monitoring the populations of four protected avian species in the wider area of Messolonghi and the lower Achelloos river in 2012: Dalmatian pelican, white stork, lesser kestrel, and griffon vulture. Self-published report, 48 p. (In Greek).

Sidiropoulos, P., Papadimitriou, Th., Stabouli, S., Loukas, A., Mylopoulos, N. & Kagalou, I. (2012) Past, present and future concepts for conservation of the re-constructed Lake Karla (Thessaly, Greece). Fresen Environ Bull 10, 1–8. Retrieved from: https://www.prt-parlar.de/download_feb_2012/

Spon, J. & Wheler, G. (1979) Voyage d' Italie, de Dalmatie, de Grèce, et du Levant fait és anées 1675 & 1676. Amsterdam: Henry & Theodore Boom. Retrieved from: https://archive.org/details/voyageditalied02spon
<table><caption>Table S2: Estimated apparently occupied Dalmatian pelican nests in the colonies of Greece 1967-2021</caption><thead><tr><th>YEAR</th><th>Prespa</th><th>Kerkini</th><th>Karla</th><th>Cheimaditis</th><th>Amvrakikos</th><th>Messolonghi</th><th>GREECE</th></tr></thead><tbody><tr><td>1967</td><td>no data</td><td></td><td></td><td></td><td>18--20</td><td></td><td>-</td></tr><tr><td>1968</td><td>70-120</td><td></td><td></td><td></td><td>no data</td><td></td><td>-</td></tr><tr><td>1969</td><td>70</td><td></td><td></td><td></td><td>19--20</td><td></td><td>c.90</td></tr><tr><td>1970</td><td>40-50</td><td></td><td></td><td></td><td>no data</td><td></td><td>-</td></tr><tr><td>1971</td><td>80-100</td><td></td><td></td><td></td><td>20</td><td></td><td>100-120</td></tr><tr><td>1972</td><td>100-120</td><td></td><td></td><td></td><td>no data</td><td></td><td>-</td></tr><tr><td>1973</td><td>80-100</td><td></td><td></td><td></td><td>no data</td><td></td><td>-</td></tr><tr><td>1974</td><td>no data</td><td></td><td></td><td></td><td>no data</td><td></td><td>-</td></tr><tr><td>1975</td><td>50-70</td><td></td><td></td><td></td><td>no data</td><td></td><td>-</td></tr><tr><td>1976</td><td>40-50</td><td></td><td></td><td></td><td>no data</td><td></td><td>-</td></tr><tr><td>1977</td><td>&gt;120</td><td></td><td></td><td></td><td>no data</td><td></td><td>-</td></tr><tr><td>1978</td><td>&gt;35</td><td></td><td></td><td></td><td>no data</td><td></td><td>-</td></tr><tr><td>1979</td><td>150</td><td></td><td></td><td></td><td>35</td><td></td><td>185</td></tr><tr><td>1980</td><td>no data</td><td></td><td></td><td></td><td>15</td><td></td><td>-</td></tr><tr><td>1981</td><td>no data</td><td></td><td></td><td></td><td>15</td><td></td><td>-</td></tr><tr><td>1982</td><td>no data</td><td></td><td></td><td></td><td>20</td><td></td><td>-</td></tr><tr><td>1983</td><td>114</td><td></td><td></td><td></td><td>12</td><td></td><td>126</td></tr><tr><td>1984</td><td>165</td><td></td><td></td><td></td><td>19</td><td></td><td>184</td></tr><tr><td>1985</td><td>139</td><td></td><td></td><td></td><td>27</td><td></td><td>166</td></tr><tr><td>1986</td><td>133</td><td></td><td></td><td></td><td>36</td><td></td><td>169</td></tr><tr><td>1987</td><td>143</td><td></td><td></td><td></td><td>31</td><td></td><td>174</td></tr><tr><td>1988</td><td>114</td><td></td><td></td><td></td><td>38</td><td></td><td>152</td></tr><tr><td>1989</td><td>163</td><td></td><td></td><td></td><td>39</td><td></td><td>202</td></tr><tr><td>1990</td><td>202</td><td>15-17</td><td></td><td></td><td>28</td><td></td><td>243</td></tr><tr><td>1991</td><td>205</td><td></td><td></td><td></td><td>50</td><td></td><td>255</td></tr><tr><td>1992</td><td>235</td><td></td><td></td><td></td><td>41</td><td></td><td>276</td></tr><tr><td>1993</td><td>245</td><td></td><td></td><td></td><td>50</td><td></td><td>295</td></tr><tr><td>1994</td><td>380</td><td></td><td></td><td></td><td>46</td><td></td><td>426</td></tr><tr><td>1995</td><td>447</td><td></td><td></td><td></td><td>56</td><td></td><td>503</td></tr><tr><td>1996</td><td>414</td><td></td><td></td><td></td><td>74</td><td></td><td>488</td></tr><tr><td>1997</td><td>455</td><td></td><td></td><td></td><td>63</td><td></td><td>518</td></tr><tr><td>1998</td><td>607</td><td></td><td></td><td></td><td>79</td><td></td><td>686</td></tr><tr><td>1999</td><td>659</td><td></td><td></td><td></td><td>82</td><td></td><td>741</td></tr><tr><td>2000</td><td>666</td><td></td><td></td><td></td><td>93</td><td></td><td>759</td></tr><tr><td>2001</td><td>602</td><td></td><td></td><td></td><td>106</td><td></td><td>708</td></tr><tr><td>2002</td><td>597</td><td>52</td><td></td><td></td><td>95</td><td></td><td>742</td></tr><tr><td>2003</td><td>1,016</td><td>7</td><td></td><td></td><td>120</td><td></td><td>1,143</td></tr><tr><td>2004</td><td>1,025</td><td>22</td><td></td><td></td><td>126</td><td></td><td>1,173</td></tr><tr><td>2005</td><td>991</td><td>58</td><td></td><td></td><td>116</td><td></td><td>1,165</td></tr><tr><td>2006</td><td>996</td><td>60</td><td></td><td></td><td>104</td><td></td><td>1,160</td></tr><tr><td>2007</td><td>1,102</td><td>65</td><td></td><td></td><td>140</td><td></td><td>1,307</td></tr></tbody></table>
<table><tr><td>2008</td><td>1,112</td><td>61</td><td></td><td>124</td><td></td><td>1,297</td></tr><tr><td>2009</td><td>1,522</td><td>61</td><td></td><td>143</td><td></td><td>1,726</td></tr><tr><td>2010</td><td>1,169</td><td>120</td><td></td><td>137</td><td></td><td>1,426</td></tr><tr><td>2011</td><td>1,155</td><td>78</td><td>1</td><td>N/A</td><td>8</td><td>N/A</td></tr><tr><td>2012</td><td>1241</td><td>68</td><td>1</td><td>162</td><td>13</td><td>1,485</td></tr><tr><td>2013</td><td>1,131</td><td>130</td><td>22</td><td>125</td><td>48</td><td>1,456</td></tr><tr><td>2014</td><td>1,125</td><td>233</td><td>53</td><td>161</td><td>40</td><td>1,637</td></tr><tr><td>2015</td><td>1,276</td><td>160</td><td>112</td><td>130</td><td>67</td><td>1,780</td></tr><tr><td>2016</td><td>1,349</td><td>215</td><td>257</td><td>151</td><td>78</td><td>2,090</td></tr><tr><td>2017</td><td>1,226</td><td>130</td><td>445</td><td>153</td><td>84</td><td>2,098</td></tr><tr><td>2018</td><td>1,266</td><td>249</td><td>346</td><td>151</td><td>51</td><td>2,131</td></tr><tr><td>2019</td><td>1,405</td><td>205</td><td>79</td><td>134</td><td>68</td><td>2,023</td></tr><tr><td>2020</td><td>1,585</td><td>60</td><td>155</td><td>168</td><td>100</td><td>2,197</td></tr><tr><td>2021</td><td>1,370</td><td>125</td><td>256</td><td>187</td><td>200</td><td>2,275</td></tr></table>

## Data sources

* Prespa: 1968-1979: Crivelli 1980 (modified according to Hatzilacou 1993); 1983-1986: Pyrovetsi & Crivelli 1988; 1987-1992: Catsadorakis et al. 1996; 1993-2000: Crivelli & Catsadorakis (unpublished data); 2001-2010: SPP & Crivelli (unpublished data); 2011-2021: SPP (unpublished data).

* Amvrakikos: 1967-1979: Crivelli 1980; 1980-1989: Hatzilacou 1993; 1990-2010: Crivelli & Hatzilacou (unpublished data); 2011-2021: N.E.C.C.A.

* Kerkini: 1990: Pyrovetsi 1997; 2002-2015: Crivelli & Naziridis (unpublished data); 2016-2021: N.E.C.C.A.

* Karla: 2011-2017: Catsadorakis 2018; 2018-2021: N.E.C.C.A. & SPP

* Cheimaditis: 2017-2021: SPP (unpublished data)

* Messolonghi: 2011: Roussopoulos 2012; 2012-2021: N.E.C.C.A.

<table><caption>Table S3: Estimated Dalmatian pelican Breeding Success (near-fledged young per Apparently Occupied Nest) in the colonies of Greece, 2012-2021. Data sources: Prespa and Cheimaditis: SPP; Karla: N.E.C.C.A. & SPP, Kerkini, Messolonghi and Amvrakikos: N.E.C.C.A.)</caption><thead><tr><th>YEAR</th><th>PRESPA</th><th>CHEIMADITIS</th><th>KERKINI</th><th>KARLA</th><th>MESSOLONGHI</th><th>AMVRAKIKOS</th></tr></thead><tbody><tr><td>2012</td><td>no data</td><td></td><td>no data</td><td>no data</td><td>no data</td><td>0.68</td></tr><tr><td>2013</td><td>no data</td><td></td><td>1.43</td><td>0.57</td><td>0.65</td><td>0.3</td></tr><tr><td>2014</td><td>0.92</td><td></td><td>1.14</td><td>0.88</td><td>0.4</td><td>1.24</td></tr><tr><td>2015</td><td>1.03</td><td></td><td>1.16</td><td>0.57</td><td>1.3</td><td>no data</td></tr><tr><td>2016</td><td>no data</td><td></td><td>1.12</td><td>no data</td><td>0.77</td><td>no data</td></tr><tr><td>2017</td><td>0.95</td><td>1.15</td><td>1.23</td><td>0.7</td><td>0.78</td><td>no data</td></tr><tr><td>2018</td><td>0.73</td><td>0.66</td><td>1.12</td><td>0.4</td><td>1.37</td><td>0.97</td></tr><tr><td>2019</td><td>0.74</td><td>0.87</td><td>1.2</td><td>1.1</td><td>0.96</td><td>0.98</td></tr><tr><td>2020</td><td>0.44</td><td>0.29</td><td>0.68</td><td>0.74</td><td>0.95</td><td>1.15</td></tr><tr><td>2021</td><td>0.68</td><td>0.77</td><td>0.9</td><td>0.62</td><td>0.75</td><td>1.08</td></tr></tbody></table>