Significance of wetlands for the conservation of avifauna in the central zone of Tigray, northern Ethiopia

doi:10.21203/rs.3.rs-3291863/v1

This study was conducted to investigate the significance of wetlands for bird conservation from June 2022 to May 2023 in the central zone of Tigray, northern Ethiopia. The point count method was used to study the bird assemblage structure and diversity in the study sites. During data analysis, the Shannon–Weaver diversity index was employed using PAST software. A total of 4,324 individual birds belonging to 125 species, 14 orders and 42 families were identified. The order Passeriformes was recorded with the highest number of species (70, 56%), followed by the order Columbiformes (9, 7.2%). Overall bird species diversity and abundance were higher during the wet season at all studied sites. The highest (100, 42%) and lowest (66, 27%) numbers of bird species were recorded in May Abakat and May Shingurti, respectively. The bird community similarity of the studied habitats was SI = 0.492, which is < 50%, indicating that there is low similarity of bird species among the three wetlands. There was no significant difference (p > 0.05) in the abundance of bird species between the wet and dry seasons except in the May Shingurti wetland. Generally, the abundance of bird species among the three selected wetlands showed highly significant variation (p < 0.05). Solid waste disposal, erosion, agricultural expansion, urbanization (human settlement), grazing by domestic stock, military camping, Eucalyptus cultivation and others were identified as wetland threats. Finally, community-based conservation initiatives should be developed and implemented to diminish the threats and safeguard the studied wetlands.

Species abundance

Species diversity

Species similarity

Wetland threats

Wetlands are ecosystems or units of the landscape that are found on the interface between land and water. While water is a major factor in wetland definition (Ramsar Convention Bureau 1997), soils, vegetation and animal life also contribute to their unique characteristics (Koetze 1996). Mitsch and Gosselink 1993 described wetlands as ‘the kidneys of the landscape’ because of the functions they perform in the hydrological and chemical cycles and as ‘biological supermarkets’ because of the extensive food webs and rich biodiversity that they support. Wetlands are distributed all over the globe and are estimated to cover approximately 6.4% of the earth’s surface (Sutherland et al. 2004) – some 5.7 million km² (WCMC 1992). Although Africa is best known for its savannahs and hot deserts, 1% of its surface area (345,000 km²) is covered by wetlands (Finlayson and Moser 1991). Hillman (1993) listed a total of 77 wetlands in Ethiopia covering an area of 13,699 km² or 1.4% of the country’s land surface.

Wetlands play critical ecosystem roles, such as biodiversity conservation, hydrological balance, and human welfare (Woldemariam et al. 2018). A wide variety of birds use wetland habitats for all or part of their lives (Patra et al. 2010). There are two categories of wetland birds: wetland specialists and generalists. Wetland specialists are birds that are entirely dependent on aquatic habitats and cannot survive in any other environment. Generalists, on the other hand, are birds that visit and rely on wetland habitats for food, shelter, and perching (Wetlands International 2012).

Birds can be used as bioindicators with which to identify wetlands of international importance. Wetland birds are extremely diverse, reflecting early anatomical and physiological adaptations to this unique but rich habitat. In Ethiopia, 204 (approximately 25%) bird species are wetland dependent. Several birds are among the few ancient ancestors that survived whatever cataclysmic events caused the die-off of the dinosaurs (Gibbons 1997), strongly suggesting that a wet habitat was a good place to be early in the history of bird evolution and that it still is. Bird species have a significant functional role in wetlands (Arruda et al. 2018). The diversity and abundance of these species vary with the seasons and types of habitat and are highly impacted by anthropogenic activities close to habitats.

The causes of wetland degradation include the conversion of wetlands for intensive irrigation agriculture, the expansion of human settlement, industrial pollution, pesticides and fertilizers and water diversion for drainage and the construction of dams. Wetland conversion often results in water depletion, the displacement of populations, the destruction of traditional production systems, habitat degradation, salinization, increases in waterborne diseases and other adverse ecological impacts (WCED 1987).

In Tigray, previous studies focused on forest and aquatic bird community composition were conducted by (Tsehaye Asmelash et al. 2007; Hailemariam Areaya et al. 2013; Kiros Welegeriam et al. 2014; Kalayu Mesfin and Gebremedhin Teklu 2014; Teklay Girmay et al. 2020) but there was a lack of scientific studies regarding the significance of wetlands for bird species in Tigray. Therefore, the purpose of this study was to assess the spatiotemporal variations in bird species diversity and abundance in the three wetlands in Tigray, Northern Ethiopia.

Study area

The research was carried out in three wetlands (May Abakat, Hatsebo and Mayshigurti) that are found in the central zone of the Tigray regional state, northern Ethiopia. Both the May Abakat and Hatsebo wetlands are found approximately 3 km from the ancient historical town of Axum, but Mayshigurti is also approximately 5 km west of Adwa town. Axum is found 251 km from the capital city of Tigray national regional state of Mekelle. Its average altitude is 2056 meters above sea level (m.a.s.l), with an average temperature of 20.6°C. The mean annual rainfall of the reservoir is 663 mm, and the pattern of rainfall distribution is unimodal with a long rainy season between June and September. All the studied wetlands are surrounded by agricultural fields, and urban expansion is highly affected. During the dry season, the wetlands are used for livestock grazing. The wetlands under study were found in a variety of landscape places and settings, such as floodplain channels used as lower catchment regions, springs, rivers, open shallow water bodies and open grazing land plains.

Figure 1 Study sites in the central zone of Tigray

Data collection

During June 2022, a preliminary survey was conducted in the selected wetlands to determine a suitable site selection and sampling strategy. Seasonal data collection was conducted three times during the wet season (July to September) and dry season (February to April). At each study site, GPS was used to locate the points for the bird-counting methods.

The point count method was used to study the bird assemblage structure and diversity in the study sites. Data were recorded by distributing points in the given wetland and selecting points from the distributed points on a random basis. Two counting blocks for the May Abakat and May Shingurtii wetlands and three counting blocks for the Hatsebo wetlands were used. For each counting block, six to eight point counts were used for each wetland habitat in each season. Birds were systematically counted twice a day in the early morning (8:30–11:30 hr) and in the late afternoon (9:30–11: 30 hr) using a Celestron (10 × 50) binocular and the naked eye where bird activity was maximum and on days with good weather conditions (Hailemariam Areaya et al. 2013; Kalayu Mesfin and Gebremedhin Teklu 2014). In addition, photographs and videos were captured to count too many birds that were difficult to identify during the field. Identification of the birds to the species level was made using appropriate field guides (Stevenson and Fanshawe 2002, Sinclair and Ryan 2003, Redman et al. 2009). To identify the current threats of the selected wetlands, field observations and focal group discussions were also applied.

To collect data on the current threats of the selected wetlands, a total of 30 respondents from both sexes were selected purposively, and then a semistructured questionnaire was used. In addition, careful observation and recording of information based on the threats of birds was carried out by using surveillance checklists. During in situ observation, a digital camera was used to record the anthropogenic practices in and around the wetland.

Data analysis

All the recorded wetland bird species were calculated using the Simpson diversity index as described by Akosim et al. (2008). The model is as follows:

Where D = Shannon index and Pi is the proportion of the species in the sample. Significant differences in bird species between sites where the maximum number of bird species was recorded were tested using the Mann‒Whitney test, and tests were set at P = 0.05.

A statistically independent sample t test was employed to estimate the seasonal and spatial effects on bird species abundance and distribution. The similarity among habitats and seasons in terms of bird species composition was evaluated using the similarity index (SI) = 2C/A + B) (Sorenson 1948). Where SI denotes the similarity index, A denotes the number of species found at site A, B denotes the number of species found at site B, and C denotes the number of species found at both sites A and B.

Avian diversity

A total of 4,324 individual birds belonging to 125 species, 14 orders and 42 families were recorded in the May Abakat, Hatsebo and May Shingurti wetlands. The order Passeriformes was recorded with the highest number of species (70, 56%), followed by the order Columbiformes (9, 7.2%). On the other hand, orders Accipitroformes, Anseriformes, Apodiformes, Coliiformes, Pelecaniformes and Piciformes were recorded with single species (1, 0.8%) each. This study showed that the highest number of bird species was recorded from Muscicapidae (13, 30.9%), followed by Ploceidae (12, 28.6%), during the study period (Table 1). The highest number of individual birds (2787, 64%) was recorded during the wet season. Comparing the three wetlands, May Shingurti had the highest number of individual birds, which was 2242 (52%). Of the 45 bird species recorded in May Abakat, 63 and 37 species were recorded during the wet season and the dry season, respectively. A total of 66 species were recorded during the wet season, and 33 species were recorded during the dry season in Hatsebo. Furthermore, in May Abakat, 102 species were recorded during the wet season, and 71 were recorded during the dry season. A total of 40 species in May Abakat, 23 species in Hatsebo and 69 species in May Shingurti were observed throughout the study period. In general, overall bird species diversity and abundance were higher during the wet season at all studied sites.

Table 1

Spatio-temporal abundance and diversity of birds
Bird species								Wetlands and sampling season
Bird species				May Abekat				Hatsebo			May Shingurti
Common name	Scientific name	Order	Family	Wet	Dry	Total	Wet	Dry	Total	Wet	Dry	Total
Abyssinian Slaty Flycatcher	Melaenornis chocolatinus	Passeriformes	Muscicapidae	8	0	8	5	2	7	0	3	3
Collared Flycatcher	Ficedula albicollis	Passeriformes	Muscicapidae	2	0	2	1	0	1	13	6	19
Gambaga Flycatcher	Muscicapa gambaga	Passeriformes	Muscicapidae	1	0	1	0	0	0	0	0	0
Mocking Cliff Chat	Thamnolaea cinnamomeiventris	Passeriformes	Muscicapidae	4	0	4	3	2	5	6	0	6
Pied Wheatear	Oenanthe pleschanka	Passeriformes	Muscicapidae	0	0	0	0	0	0	16	11	27
Pallid Flycatcher	Bradornis pallidus	Passeriformes	Muscicapidae	0	0	0	9	0	9	0	0	0
Northern Anteater Chat	Myrmecocichla aethiops	Passeriformes	Muscicapidae	0	0	0	13	0	13	26	19	45
Mocking Cliff Chat	Thamnolaea cinnamomeiventris	Passeriformes	Muscicapidae	22	0	22	9	11	20	19	0	19
Pied Wheatear	Oenanthe pleschanka	Passeriformes	Muscicapidae	0	0	0	0	0	0	32	13	45
Northern Anteater Chat	Myrmecocichla aethiops	Passeriformes	Muscicapidae	0	0	0	6	0	6	8	11	19
Grayish Flycatcher	Bradornis microrhynchus pumilus	Passeriformes	Muscicapidae	11	6	17	9	2	11	0	0	0
Abyssinian Catbird	Parophasma gainieri	Passeriformes	Timaliidae	3	1	4	9	0	9	15	5	20
Abyssinian Longclaw	Macronyx flavicollis	Passeriformes	Motacillidae	29	16	45	0	0	0	13	0	13
African Citril	Serinus citrinelloides	Passeriformes	Fringillidae	9	0	9	23	16	39	17	29	46
African Rook	Corvus capensis	Passeriformes	Corvidae	2	6	8	9	0	9	12	2	14
African Pied Wagtail	Motacilla aguimp	Passeriformes	Motacillidae	0	0	0	9	3	12	9	1	10
African Thrush	Turdus pelios	Passeriformes	Turdidae	0	21	21	12	0	12	28	17	45
Beautiful Sunbird	Nectarinia puchella	Passeriformes	Nectariniidae	14	6	20	3	0	3	23	8	31
Black-Headed Weaver	Ploceus melanocephalus	Passeriformes	Ploceidae	8	0	8	3	0	3	0	5	5
Black-Headed Gonolek	Laniarius erythrogaster	Passeriformes	Malaconotidae	0	0	0	0	0	0	3	1	4
Black-Winged Red Bishop	Euplectes hordeaceus	Passeriformes	Ploceidae	38	0	38	13	0	13	61	0	61
Blue-Cheeked Cordianblue	Uraeginthus angolensis	Passeriformes	Estrildidae	42	22	64	11	0	11	42	36	78
Brown-Ramped Seedeater	Crithagra tristriatus	Passeriformes	Fringillidae	6	12	18	17	0	17	0	9	9
Chestnut-Backed Sparrow-Lark	Eremopterix leucotis	Passeriformes	Alaudidae	0	0	0	0	0	0	3	1	4
Chestnut-Crowned Sparrow-Weaver	Ploceus rubiginosus	Passeriformes	Ploceidae	0	0	0	0	0	0	16	9	25
Cinnamon-Breasted Rock Bunting	Emberiza tahapisi	Passeriformes	Emberizidae	0	0	0	0	0	0	1	0	1
Citrine Wagtail	Motacilla citreola	Passeriformes	Motacillidae	0	0	0	0	13	13	17	8	25
Bronze-Tailed Starling	Lamprotornis chalcurus	Passeriformes	Sturnidae	0	0	0	9	0	9	13	0	13
Common Bulbul	Pycnonotus barbatus	Passeriformes	Pcynonotidae	19	0	19	8	0	8	22	17	39
Common Camaroptera	Camaroptera brachyuran	Passeriformes	Cisticolidae	3	0	3	1	0	1	7	3	10
Common Fiscal	Lanius collaris	Passeriformes	Laniidae	0	9	9	17	0	17	31	16	47
Common Waxbill	Estrilda astrild	Passeriformes	Estrildidae	24	29	53	0	0	0	26	10	36
Compact Weaver	Pachyphantes superciliosus	Passeriformes	Ploceidae	13	0	13	8	0	8	35	15	50
Copper Sunbird	Nectarinia cuprea	Passeriformes	Nectariniidae	5	0	5	2	0	2	12	4	16
Crested Lark	Galerida cristata	Passeriformes	Alaudidae	23	9	32	11	7	18	38	10	48
Croaking Cisticola	Cisticola natlensis	Passeriformes	Cisticolidae	0	0	0	0	0	0	18	21	39
Cut-Throat	Amadina fasciata	Passeriformes	Estrildidae	0	0	0	0	0	0	7	0	7
Eastern Olivaceous Warbler	Hippolais pallida	Passeriformes	Sylviidae	0	0	0	27	0	27	0	0	0
Fan-Tailed Raven	Corvus rhipidurus	Passeriformes	Corvidae	19	25	44	29	17	46	33	13	46
Foxy Cisticola	Cisticola troglodytes	Passeriformes	Cisticolidae	0	0	0	0	8	8	22	15	37
Grey Headed Sparrow	Passer griseus	Passeriformes	Passeridae	0	0	0	0	0	0	9	0	9
Groundscraper Thrush	Psophocichla litsitsirupa	Passeriformes	Turdidae	28	32	60	0	11	11	27	14	41
Hunter’s Cisticola	Cisticola cantans	Passeriformes	Cisticolidae	0	0	0	6	0	6	0	0	0
Lead-Coloured Flycatcher	Myioparus plumbeus	Passeriformes	Nectariniidae	0	0	0	0	0	0	10	15	25
Icterine-Warbler	Hippolais icterina	Passeriformes	Acrocephalidae	0	0	0	0	0	0	32	39	71
Little Weaver	Ploceus luteolus	Passeriformes	Ploceidae	0	0	0	37	21	58	51	17	68
Long-Billed Pipit	Anthus similis	Passeriformes	Motacillidae	0	0	0	0	0	0	9	0	9
Mountain Wagtail	Motacilla clara	Passeriformes	Accipitridae	0	0	0	7	0	7	3	1	4
Northern Black Tit	Parus leucomelas	Passeriformes	Paridae	0	0	0	0	0	0	6	11	17
Northern Masked Weaver	Ploceus taeniopterus	Passeriformes	Ploceidae	0	0	0	0	0	0	5	0	5
Northern Red Bishop	Euplectes franciscanus	Passeriformes	Ploceidae	13	0	13	0	0	0	0	0	0
Pied Crow	Corvus albus	Passeriformes	Corvidae	8	12	20	9	5	14	0	0	0
Red-Billed Firefinch	Lagonosticta senegala	Passeriformes	Fringillidae	0	0	0	5	0	5	13	7	20
Red-Cheeked Cordian-Blue	Uraeginthus bengalus	Passeriformes	Fringillidae	32	24	56	28	0	28	43	25	68
Red-collared widowbird	Euplectes ardens	Passeriformes	Ploceidae	0	0	0	36	0	36	39	0	39
Red-Throated Pipit	Anthus cervinus	Passeriformes	Motacillidae	7	0	7	9	3	12	17	5	22
Red-Winged Starling	Onychognthus morio	Passeriformes	Sturnidae	6	0	6	11	0	11	32	37	69
Short-Tailed Lark	Pseudalaemon fremantlii	Passeriformes	Alaudidae	0	0	0	0	0	0	15	7	22
Speke's Weaver	Ploceus speki	Passeriformes	Ploceidae	0	0	0	20	0	20	17	21	38
Streaky-Headed Seedeater	Serinus gularis	Passeriformes	Fringillidae	5	0	5	0	0	0	0	0	0
Stripe-Breasted Seedeater	Serinus reichardi	Passeriformes	Fringillidae	9	11	20	0	3	3	7	2	9
Tropical Boubou	Laniarius aethiopicus	Passeriformes	Malaconotidae	0	0	0	0	0	0	8	4	12
Spectacled Weaver	Ploceus ocularis	Passeriformes	Ploceidae	0	0	0	0	0	0	21	17	38
Tawny Pipit	Anthus campestris	Passeriformes	Motacillidae	0	0	0	0	0	0	3	0	3
Spotted Flycatcher	Muscicapa striata	Passeriformes	Muscicapidae	7	9	16	10	9	19	3	7	10
Spotted Morning Thrush	Cichladusa guttata	Passeriformes	Sturnidae	0	0	0	0	0	0	5	7	12
Village Indigobird	Vidua chalybeata	Passeriformes	Viduidae	3	0	3	7	0	7	1	0	1
White-Winged Cliff-Chat	Myrmecocichla semirufa	Passeriformes	Muscicapidae	13	10	23	8	0	8	0	0	0
White Fronted Black Chat	Epthianura albifrons	Passeriformes	Muscicapidae	0	0	0	0	0	0	7	0	7
Wire-Tailed Swallow	Hirundo smithii	Passeriformes	Hirundinidae	0	0	0	0	0	0	5	2	7
White-Crowned Black-Wheatear	Vidua paradisaea	Passeriformes	Viduidae	0	0	0	0	0	0	19	23	42
African Mourning Dove	Streptopelia decipiens	Columbiformes	Columbidae	9	12	21	5	0	5	18	12	30
Collared Dove	Streptopelia decaocto	Columbiformes	Columbidae	13	0	13	22	17	39	31	34	65
Bruce’s Green Pigeon	Treron waalia	Columbiformes	Columbidae	0	0	0	0	0	0	3	0	3
Namaqua Dove	Oena capensis	Columbiformes	Columbidae	3	1	4	1	0	1	0	0	0
Lemon Dove	Columba larvata	Columbiformes	Columbidae	21	8	29	25	13	38	0	0	0
Dusky Turtle-Dove	Streptopelia lugens	Columbiformes	Columbidae	18	11	29	9	5	14	0	5	5
Red-Eyed Dove	Streptopelia semitorquata	Columbiformes	Columbidae	0	0	0	0	0	0	9	13	22
Speckled Pigeon	Columba guinea	Columbiformes	Columbidae	21	27	48	7	0	7	35	31	66
Ring Necked Dove	Streptopelia capicola	Columbiformes	Columbidae	16	11	27	5	0	5	0	7	7
Common Ringed Plover	Charadrius hiaticula	Charadriiformes	Charadriidae	4	0	4	0	0	0	0	0	0
Common Sandpiper	Actitis hypoleucos	Charadriiformes	Scolopacidae	0	0	0	0	0	0	5	3	8
Little Ringed Plover	Charadrius dubius	Charadriiformes	Charadriidae	1	0	1	0	0	0	0	0	0
Ruff	Calidris pugnax	Charadriiformes	Scolopacidae	3	0	3	2	0	2	0	0	0
Senegal Thick-Knee	Burnings senegalensis	Charadriiformes	Burhinidae	17	8	25	0	7	7	5	0	5
Stone Curlew	Burhinus oedicnemus	Charadriiformes	Scolopacidae	8	0	8	0	4	4	0	0	0
White Fronted Plover	Charadrius marginatus	Charadriiformes	Charadriidae	9	0	9	0	0	0	0	0	0
Spur-Winged Lapwing	Vanellus spinosus	Charadriiformes	Charadriidae	6	0	6	0	0	0	11	14	25
Spur-winged lapwing	Vanellus spinosus	Charadriiformes	Charadriidae	0	0	0	0	0	0	13	9	22
Black stork	Ciconia nigra	Ciconiiformes	Ciconiidae	5	0	5	3	0	3	0	0	0
Cattle Egret	Bubulcus ibis	Ciconiiformes	Ardeidae	15	8	23	13	11	24	0	7	7
Greater White Egret	Egretta alba	Ciconiiformes	Ardeidae	6	0	6	3	0	3	0	0	0
Grey Heron	Ardea cinerea	Ciconiiformes	Ardeidae	0	0	0	5	0	5	3	7	10
Little Egret	Egretta garzetta	Ciconiiformes	Ardeidae	16	13	29	11	14	25	0	0	0
Yellow-Billed Egret	Egretta intermedia	Ciconiiformes	Ardeidae	11	9	20	0	0	0	0	0	0
Wattled Ibis	Bostrychia carunculata	Ciconiiformes	Threskiorithidae	15	10	25	0	0	0	26	12	38
Hamerkop	Scorpus umbretta	Ciconiiformes	Scopidae	6	4	10	3	0	3	7	4	11
Grasshopper Buzzard	Butastur rufipennis	Falconiformes	Accipitridae	0	0	0	5	9	14	0	0	0
Lappet-Faced Vulture	Torgos tracheliotos	Falconiformes	Accipitridae	11	0	11	0	0	0	0	0	0
Long-Legged Buzzard	Buteo rufinus	Falconiformes	Accipitridae	0	0	0	16	0	16	0	0	0
Augur Buzzard	Buteo augur	Falconiformes	Accipitridae	0	0	0	7	0	7	0	0	0
Pallid Harrier	Circus macrourus	Falconiformes	Accipitridae	0	0	0	0	0	0	1	0	1
Peregrine Falcon	Falco peregrinus	Falconiformes	Falconidae	0	0	0	0	0	0	5	2	7
Short-Toed Snake-Eagle	Circaetus gallicus	Falconiformes	Accipitridae	0	0	0	0	0	0	1	0	1
Ovampo Sparrowhawk	Accipiter ovampensis	Falconiformes	Accipitridae	0	0	0	0	0	0	3	0	3
Clapperton's Francolin	Francolinus clappertoni	Galliformes	Phasianidae	12	14	26	0	0	0	13	8	21
Common Quail	Coturnix coturnix	Galliformes	Phasianidae	8	0	8	0	2	2	1	3	4
Crested Francolin	Francolinus sephaena	Galliformes	Phasianidae	0	0	0	0	0	0	3	6	9
Scaly Francolin	Francolinus squamatus	Galliformes	Phasianidae	0	0	0	3	0	3	12	5	17
Helmeted Guineafowl	Numida meleagris	Galliformes	Numididae	8	3	11	0	0	0	5	7	12
Smith’s Francolin	Francolinus levaillantoides	Galliformes	Phasianidae	0	0	0	0	0	0	6	0	6
Black Wood-Hoopoe	Phoeniculus aterrimus	Coraciiformes	Phoeniculidae	0	0	0	0	0	0	1	2	3
Blue-Breasted Bee-Eater	Merops variegatus	Coraciiformes	Meropidae	0	3	3	9	4	13	5	1	6
White Throated Bee-Eater	Merops bullockides	Coraciiformes	Meropidae	0	0	0	0	0	0	4	2	6
Malachite Kingfisher	Alcedo cristata	Coraciiformes	Alcedinidae	0	0	0	0	0	0	7	6	13
Little Bee-Eater	Merops pusillus	Coraciiformes	Meropidae	0	0	0	0	0	0	15	11	26
Pied Kingfisher	Ceryle rudis	Coraciiformes	Alcedinidae	0	0	0	3	0	3	5	2	7
Black-Winged Lovebird	Agapornis taranta	Psittaciformes	Psittacidae	9	8	17	2	4	6	15	5	20
Baglafecht Weaver	Ploceus baglafecht	Psittaciformes	Ploceidae	16	0	16	0	7	7	14	9	23
Black-Billed Barbet	Lybius guifsobalito	Piciformes	Lybiidae	0	0	0	27	11	38	6	11	17
Black Kite	Milvus migrans	Accipitroformes	Accipitiridae	3	7	10	1	1	2	0	7	7
Egyptian Goose	Alopochen aegyptiacus	Anseriformes	Anatidae	12	0	12	5	0	5	35	21	56
Nyanza Swift	Apus niansae	Apodiformes	Apodidae	0	0	0	3	7	10	0	3	3
Squacco heron	Ardeola ralloides	Pelecaniformes	Ardeidae	0	9	9	0	5	5	0	0	0
Speckled Mousebird	Colius striatus	Coliiformes	Coliidae	0	0	0	0	0	0	11	9	20

Table 1. Spatiotemporal abundance and diversity of birds

Species diversity indices

During the study period, bird species diversity varied among the three studied wetlands (Table 2). The highest (100, 42%) and lowest (66, 27%) numbers of bird species were recorded in May Abakat and May Shingurti, respectively. May Shingurti had the highest bird species diversity during the wet season (H' = 4.2) and dry season (H' = 4.706). However, the lowest bird species diversity during the wet season (H' = 3.785) and during the dry season (H' = 3.251) was observed in May in Abakat and Hatsebo, respectively. The highest species evenness (E = 0.816) was observed in May Abakat during the dry season, but the lowest species evenness (E = 0.725) was observed during the wet season in May Shingurti. May Abaket had the highest species evenness (E = 0.722), as the compiled data indicated. May Shingurti during the wet season and Hatsebo during the dry season had the highest (D = 0.981) and lowest (D = 0.955) Simpson diversity index values of bird species.

Table 2

Bird species diversity indices among three wetlands during wet and dry seasons
Wetlands	Season	No. of species	Abundance	D	H´	E
May Abakat	Wet	62	738	0.975	3.785	0.776
	Dry	36	426	0.960	3.381	0.816
	Both	66	1164	0.973	3.865	0.722
Hatsebo	Wet	65	664	0.974	3.871	0.738
	Dry	32	254	0.955	3.251	0.807
	Both	74	918	0.974	3.947	0.399
May Shingurti	Wet	92	1385	0.981	4.2	0.725
	Dry	80	857	0.978	4.076	0.736
	Both	100	2242	0.982	4.249	0.700
Where, D = Simpson Diversity Index; H´= Shannon-Wiener diversity Index; E = Evenness

Table 2. Bird species diversity indices among three wetlands during wet and dry seasons

Species similarity indices

Seasonal variations in bird species similarity among the three habitats were analyzed during the study period. Accordingly, during the wet season, species similarity was higher between the May Abakat and Hatsebo wetlands (SI = 0.646), whereas the least similarity was observed between the Hatsebo and May Shingurti wetlands (SI = 0.448) in the same season. During the dry season, higher species similarity was observed between the May Abakat and May Shingurti wetlands (SI = 0.481). Lower species similarity was recorded between the Hatsebo and May Shingurti wetlands (SI = 0.423) during the dry season (Table 3). The overall bird community similarity of the studied habitats was SI = 0.492, which is < 50%, indicating that there is low similarity of bird species among the three wetlands.

Table 3

Species similarity indices
Simpson's similarity index (SI)
Wet season				Dry season
Wetlands	May Abakat	Hatsebo	May Shingurti	Wetlands	May Abakat	Hatsebo	May Shingurti
May Abakat	-	0.646	0.448	May Abakat	-	0.457	0.481
Hatsebo	-	-	0.497	May Abakat	-	-	0.423
May Shingurti	-	-	-	Hatsebo	-	-	-

Table 3. Species similarity indices

Distribution and relative abundance of birds

From the total identified bird species in the studied wetlands, blue-cheeked cordian blue (5.69%), little weaver (5.57%) and black-winged red bishop (4.4%) were the most abundant species in the total number of counts during the wet season in the May Abakat, Hatsebo and May Shingurti wetlands, respectively. Furthermore, Groundscraper thrush (7.51%) in May Abakat, little weaver (8.26%) in Hatsebo and Icterine-Warbler (4.55%) in May Shingurti were recorded with the highest species abundance during the dry season. During this study, the species accumulation curve for the three wetlands fully reached the asymptote line, indicating the completeness of the survey and adequacy of the sampling effort. This implies that no more sampling effort is needed to explore all the expected bird species of the study wetlands. There was no significant difference (p > 0.05) in the abundance of bird species between the wet and dry seasons in both the May Abakat and Hatsebo wetlands, but highly significant seasonal variation (p < 0.05) was observed in the May Shingurti wetland. Generally, the abundance of bird species among the three selected wetlands showed highly significant variation (p < 0.05).

Figure 2 Bird species accumulation curve in selected wetlands of Tigray (A-May Abakat, B-Hatsebo, C-May Shingurti)

Spatiotemporal correlation of bird orders

Canonical Correspondence Analysis was to assess the spatiotemporal correlation of bird orders. Ciconiiformes, Falconiformes, Accipitroformes, Apodiformes and Pelecaniformes were showed positive correlation and strongly correlated with the dry season. However Passeriformes, Columbiformes, Charadriiformes, Galliformes, Coraciiformes, Psittaciformes, Piciformes, Anseriformes and Coliiformes were negative correlation and strongly correlated with the wet season.

Figure 3 Canonical Correspondence Analysis triplot of the wetlands’s with seasonal difference of bird orders. Bird’s orders eight-letter code: Piciform = Passeriformes, Columbif = Columbiformes, Charadri = Charadriiformes, Ciconiif = Ciconiiformes, Falconif = Falconiformes, Gallifor = Galliformes, Coraciif = Coraciiformes, Psittaci = Psittaciformes, Piciform = Piciformes, Accipitr = Accipitroformes, Anserifo = Anseriformes, Apodif = Apodiformes, Apodifor = Apodiformes, Pelecani = Pelecaniformes, Coliifor = Coliiformes

Threats of wetlands

While wetlands may be the most productive of ecosystems on earth, they are also the most threatened. During the study, different threats to wetlands were collected from the respondents and observed during in situ field work. Generally, solid waste disposal, erosion, agricultural expansion, urbanization (human settlement), grazing by domestic stock, military camping, Eucalyptus cultivation and others were identified as wetland threats. The May Abakat wetland is highly affected by solid waste disposal, erosion and overgrazing. Urbanization (human settlement) and grazing by domestic stock were identified as the main threats in the Hatsebo wetland. When grazing follows continuous cultivation, wetlands easily become degraded and lose their natural characteristics. These effects often result in the complete degradation of wetlands by reducing the water table and by changing the original vegetation. Eucalyptus and other plant cultivation on the edges of wetlands was observed as a threat at all study sites. Farmers are of the opinion that the cultivation of these crops and trees on the wetland edge is responsible for their drying out.

Figure 4 Threats of wetlands in the study sites

In the present study, a total of 4,324 individual birds belonging to 125 species, 14 orders and 42 families were recorded from the three wetlands. Previous research in different parts of Ethiopia suggested different results: 46 bird species under 11 orders and 30 families (Wondimagegnehu Tekalign 2012), 84 species and 23 families (Tesfahunegny 2016), 55 bird species belonging to 20 families and 9 orders (Amare Gibru and Yihew Biru 2022) and 103 avian species belonging to 47 families and 14 orders (Gibru and Mengesha 2021). The number of species recorded in the present study was much higher than that in several studies conducted in other parts of Ethiopia, which indicated that those wetlands supported a large number of bird species in the current study. Because of war and other related factors, deforestation is highly increased in the Tigray regional state, so bird species find other alternatives, such as wetlands, for survival. The abundance and species composition of birds in the present study showed significant spatiotemporal variation, which was higher during the wet season. This agrees with previous studies by (Amare Gibru and Zelalem Temesgen 2020; Numeri Awash and Wondimagegnehu Tekalig 2022). This might be due to the seasonal availability of food for different bird species and nesting sites in the area during the wet season. Other studies have also shown that seasonal variations in rainfall and food resources have led to seasonal variations in the diversity of birds (Bibi and Ali 2013). Furthermore, during the wet season, the productivity and yield of habitat increases as many of the invertebrates breed and the herbs become more productive on which the birds depend, and as a result, the richness increases. The diversity of bird species is influenced by the structure of the vegetation that forms a major component of their habitats. However, the lowest abundance and diversity of bird species shown during the dry season may be due to the presence of human disturbance and livestock grazing in the wetlands. Overgrazing is associated with the decreased physical density of vegetation, which forces the decline and loss of bird species diversity in wetlands (Scott et al. 2003). A previous study by (Numeri Awash and Wondimagegnehu Tekalign 2022) reported that the order Passeriformes is represented by the highest number of species (N = 17) in the Loga, Awetu, and Hurric wetlands of the Oromia regional state of Ethiopia, which is in line with the present finding. The order Passeriformes is the largest and most diverse order of birds, comprising over half of the world’s known bird species (Sibley and Monroe 1990). Comparing the three wetlands, May Shingurti was recorded as having the highest abundance and composition of bird species. This might be due to the presence of mountain forest near the wetland and less anthropogenic activities compared with the others. Floristic composition and vegetation structure are frequently mentioned as factors that influence the number of species found in a given area (Eshetu et al. 2018). For this reason, birds obtain an adequate place for feeding, nesting and breeding. However, the May Abakat and Hatsebo wetlands recorded the fewest species due to the significant agricultural expansion that encompasses the entire area and human settlement when compared to the May Shingurti wetland. The results of species diversity analysis revealed that bird species composition is different among areas and months because of habitat differences, seasonal movement patterns, local and regional habitat changes, large-scale population changes, and climatic conditions (Ericia et al. 2005).

In the present study, the diversity index results showed that the highest diversity of bird species was recorded in May at Shingurti (H′=4.2) during the wet season, while the lowest diversity of species was found at Hatsebo (H′=3.251) during the dry season. This might be due to livestock grazing pressure and human disturbance during the dry season in the wetlands. However, this disagrees with previous findings (Alemayehu Shiferaw and Dereje Yazezew 2021) in which species diversity increased during the dry season compared with the wet season. Blue-Cheeked Cordian blue was recorded as the dominant species during the study period. This might be due to the presence of a diverse range of habitats and favorable food availability for this species. Dominance occurs when one or more species exert control over the environment and conditions, as well as influence other species (Calimpong and Nuneza 2015).

In the present study, the species accumulation curve for the three wetlands fully reached the asymptote line, indicating the completeness of the survey and adequacy of the sampling effort. This effect is illustrated in a species accumulation curve, in which the x-axis is the number of individuals recorded and the y-axis is the number of species observed or species richness. The curve continues to rise as more individuals are sampled, but the slope becomes shallower because progressively more sampling effort is required to detect the rare species (Tokeshi and Schmid 2002). An ordinary count of the number of species in a sample is usually a biased underestimate of the true number of species in the environment simply because increasing the sampling effort (through counting more individuals, examining more sampling units, or sampling a larger area) inevitably increases the number of species (Gotell and Chao 2013).

In the case of a growing human population, agricultural expansion into wetland areas and the presence of additional lands adjacent to the wetland habitat area used for farmland place pressure on bird species inhabitants. Agricultural practices near wild habitats and rural and urban expansion activities have led to the decline and modification of habitats, causing losses of biodiversity. The outcomes of this investigation addressed some of the effects of threats to wetland habitats that directly impact bird species (Abebe and Bekele 2018). A previous study by (Amare Gibru and Zelalem Temesgen 2020) stated that habitat disturbances by overgrazing, agricultural expansion around wetlands, settlement and sand extraction were the major threats to bird species in wetlands. This is in complete agreement with the present finding, but the influence of the threats was different in each wetland. In the present study, Eucalyptus cultivation on the edges of wetlands was identified as a threat to the survival of wetland birds. These and other activities resulted in disruption, a reduction in the diversity of species in line with the devastation of habitat and high competition for foraging in the area. Improper disposal of solid waste from Axum town was observed in the present study in the May Abakat wetland, which causes pollution in the habitat and is the main threat to the avifauna. This is supported by (Amare Gibru and Zelalem Temesgen 2020) in the Cheleleka wetland.

The May Abakat, Hatsebo and May Shingurti wetlands support numerous bird populations, including 4324 individual birds belonging to 125 species, 14 orders and 42 families. During the wet season, the highest bird species composition and abundance were recorded at the study sites. Generally, the abundance of bird species among the three selected wetlands showed highly significant variation (p < 0.05). The overall bird community similarity of the studied habitat was SI = 0.492, which is < 50%, indicating that there is low similarity of bird species among the three wetlands. Solid waste disposal, erosion, agricultural expansion, urbanization (human settlement), grazing by domestic stock and Eucalyptus cultivation were identified as major wetland threats.

Community-based conservation initiatives should be developed and implemented, and accountable institutions and wetland management policies should be established to safeguard wetlands at the study sites.
Conservation measures involving the local community are needed to minimize wetland threats and to protect the biological diversity of habitats.
To limit the level of disturbance at the study sites, a controlled grazing system should be adopted, particularly during the dry season.

Acknowledgments

We would like to thank Aksum University and Mekelle Biodiversity Center for material support. We are also debited to the respondents and local administration, who gave us all necessary information during field work.

Fund: This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Data Availability

The raw data can be obtained from the ˆfirst/corresponding author upon reasonable request.

Conflicts of Interest: There are no conflicts of interest stated by the authors.

Author contributions

Kalayu Mesfin Arefayne, Alembrhan Assefa and Wldemariam Tesfahunegn collected the in situ data. Alembrhan Assefa generated and analysed the collected data. Kalayu Mesfin Arefayne and Wldemariam Tesfahunegn interpreted the results and wrote the paper. All authors contributed, read and approved the final manuscript.

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No competing interests reported.

Significance of wetlands for the conservation of avifauna in the central zone of Tigray, northern Ethiopia

Status:

Version 1

Abstract

Figures

Introduction

Methodology

Study area

Data collection

Data analysis

Result

Avian diversity

Species diversity indices

Species similarity indices

Distribution and relative abundance of birds

Spatiotemporal correlation of bird orders

Threats of wetlands

Discussion

Conclusion

Recommendation

Declarations

References

Additional Declarations

Status:

Version 1