- The study examined relationships between bird species richness, habitat characteristics, and endemic bird species across 5 sites on Tenerife. - Results showed bird species richness was positively correlated with plant species richness and biomass. Endemic bird species were positively correlated with overall bird species richness and biomass. - The laurel forest had the highest bird species count but lowest endemic species count. The scrubland had the highest total species richness and endemic species.

1. Habitat characteristics and bird species richness relationships within five sites in southern Tenerife:
implications for endemic extinction.
Abstract
Island dwelling endemic species are more specialised in their habitat selection due to increased niche competition and limite d
range. When faced with serious habitat loss, endemic species are at greater risk of extinction than non -endemics. The Pinus
canariensis forest of Tenerife is home to a number of bird species, one of which is classed as Near Threatened by the IUCN
red list and happens to be an endemic species; the blue chaffinch, Fringella teydea teydea. Historically this bird has become
increasingly endangered due to degradation and decline of its natural habitat. Using line transect distance sampling in five
diverse habitat locations across southern Tenerife, bird species abundance was recorded across three days in addition to
performing habitat surveys of key habitat characteristics such as percentage ground cover, plant species abundance and a
biomass measure. This was used to determine any correlations between bird species abundance and habitat characteristics, with
particular interest in correlations between endemics. Findings from this study determined that increasing biomass positively
correlated with bird species richness. There was a significant positive correlation between plant species richness and bird
species richness in addition to significant positive correlations between endemic bird species, increasing biomass and overall
bird species richness.
Introduction
Since the 1600’s over 60% of species extinctions have happened within island ecosystems (Algar & Losos 2011).
As we continue through the Halocene, which has become known as the sixth great extinction event (Chivian &
Bernstein 2008) extinction rates are expected to increase.
The island of Tenerife has eight endemic bird species across varying habitats, such as the Pinus canariensis forest
(Delgado et al. 2008). Island dwelling endemic species are more specialised in their habitat selection due to
increased niche competition and limited range (Owen & Bennett 2003 and Boyer & Jetz 2014) consequently they
suffer significantly under ecological stress such as habitat disruption and predation (MacArthur & Wilson 1967).
As a result endemic species are at greater risk of extinction than non-endemics (Zhai et al. and Oppel et al. and
Cimadom et al. 2014). Habitat preference, habitat characteristics and species abundance correlations can provide
understanding into the impacts of such ecological stressors (Granier et al. 2014) and help determine the best
methods of conserving and protecting endemic species within their preferred environments. This too can provide
insight as to any subsequent impacts such conservation measures may have on other endemic species that
occupy/competing for the same niche (Lange et al. 2014).
Ordinarily in mainland terrestrial habitats, when a species is in competition for a niche, the unsuccessful species is
either forced to adapt into another niche or face extinction (Mackenzie et al. 2006). Within island dynamics of
niche competition, due to occupying such a limited range; endemic species experience what is known as ecological
release. This is the release of habitat preferences commonly occurring within a species when occupying a mainland
habitat, which when faced with over competition for those same habitat preferences within an island habitat; is
forced to adapt into alternative habitats/niches (Bolnick et al. 2010). This was demonstrated in Guillaumet &
Leotard (2015) investigation into the effects of interspecific competition between Galerida cristata and Galerida
theklae which found that due to the pressures applied to Galerida cristata from interspecific competition, they
changed their habitat preference from occupying dunes and crop fields, to occupying stony hillsides and rocky
slopes.
On Tenerife, approximately 45% of its terrestrial environment is protected in an effort to conserve its native
wildlife (OAPN 2009). Conservation efforts are in place to manage catastrophic events such as forest fires (Garcia
et al. 2010), however not enough is known about the habitat preferences of endemic bird species to efficiently
establish practices aimed at increasing and sustaining population levels of endemic species via means of
preferential habitat maintenance or protection. Such an understanding could underpin better conservation efforts to
increase population levels of the Fringilla teydea teydea and protection of the species in addition to other endemic
species within Tenerife.
From the research conducted on habitat preference of F. t. teydea, it was found that during the winter months of
nonbreeding; food preference changes cause F. t. teydea to forage in mainly low height ground shrubs with
particular preference to the Adenocarpu sp. and Myrica faya (Garcia-del-Rey & Cresswell 2005 and Garcia et al.
2009). In addition to its change in habitat preference during the nonbreeding months it was found that changing
densities within the Pinus canariensis forest also affected species abundance and habitat preference of this species
causing a decline in numbers throughout regions of high tree density (Garcia et al. 2010).

2. Most of the research conducted on habitat preferences of endemic bird species on Tenerife focuses on the Fringilla
t. teydea due to its current IUCN threat level of “near threatened” (Birdlife international 2012). Though the species
abundance of the F.t. teydea on Tenerife has been assessed as common and stable (Garcia-del-Rey & Cresswell
2005) in neighbouring Gran Canaria the Fringilla teydea polatzeki has been assessed as Endangered (Garcia et al.
2013).
Aim
To determine if bird species richness is impact upon by habitat characteristics. In addition, to determine if endemic
bird species are affected by the same habitat characteristics?
From this it can be determined if current land management practices are effectively protecting endemic bird species
in the correct habitats.
Objectives
To achieve this aim, the following objectives were considered:
Obtain species richness data of bird species,biomass and species richness data of plant species within five habitats
across South Tenerife.
Determine any correlations between habitat characteristics,bird species richness and endemic bird species; that
could identify habitat preferences
Method
Location
The following five sites were selected for their diverse habitats in varying degrees of vegetation;
The Pinus canariensis forest: a high altitude, coniferous habitat with signs of fire damage and limited/patchy
ground cover or shrubbery.
The laurel forest: a mid-altitude, evergreen habitat with abundant lichen and thick ground cover/shrubbery.
Mediterranean scrubland (Arona): a low altitude, succulent/cacti abundant habitat with course/patchy grasses and
large rock formations.
Mount Teide: a high altitude, shrub dominant habitat with dry, rocky terrain.
Los Cristianos: a low altitude, urban coastline development of artificial green spaces and abundant tourist traffic.
Experimental protocol
A minimum of 200 bird samples and 200 habitat samples were the target figures to be achieved in this study to
provide adequate data entries for valid and accurate statistical analysis. A distance sampling method was used
along a 4 km transect over four hours in each site, performing a habitat survey every 100 m. Sampling were taken
over 37 points across the entirety of the transect line for all birds seen, recording number of individuals spotted, its
position in the vegetation, the species of bird and its distance from the viewer. Each observer was equipped with
the binoculars and identification chart to help determine the bird species being observed. In addition to this
whenever a bird was seen,a laser rangefinder was used to measure the birds perpendicular distance from the viewer
along the transect line. The transect line itself was formed along known footpaths due to terrain limitations and
safety of the observers. Each line was marked within a GPS to ensure an accurate measure of distance was kept.
The habitat survey was conducted every hundred metres using a 10 m x 10 m quadrate to observe and record
percentage ground cover vegetation, number of plant species and a girth measurement in metres of the three largest
plants which were then averaged to use as a biomass measure.
In total twelve researchers were divided across two habitats per day, with three researchers conducting bird surveys
and three researchers conducting habitat surveys behind the birds researchers at a delayed pace to minimise
disruption to birds in the area.

3. Results
The results gathered have been statistically explored to determine the following mean frequency counts per
recorded variable per habitat. The following habitat codes are used to identify each habitat:
1 = The Pinus canariensis forest
2 = The Laurel forest
3 = The Mediterranean scrubland (Arona)
4 = Mount Teide
5 = Los Cristianos
Habitat Code
Variable 1 2 3 4 5
Bird
Species
Count
0.730 ± 0.902
P= 0.000 n=37
1.568 ± 1.041
P= 0.003 n= 37
0.865 ± 1.041
P= 0.000 n= 37
0.556 ± 0.773
P= 0.000 n= 36
1.129 ± 1.057
P= 0.000 n= 31
Endemic
Bird Count
0.324 ± 0.530
P= 0.000 n= 37
0.378 ± 0.491
P= 0.000 n= 37
0.189 ± 0.397
P= 0.000 n= 37
0.278 ± 0.454
P= 0.000 n= 36
0.194 ± 0.402
P= 0.000 n= 31
Individual
Bird Count
1.213 ± 1.750
P= 0.000 n= 37
2.081 ± 1.722
P= 0.000 n= 37
2.000 ± 3.472
P= 0.000 n= 37
0.389 ± 1.149
P= 0.000 n= 36
2.452 ± 3.064
P= 0.000 n= 31
% Ground
Cover
8.486 ± 8.325
P= 0.000 n= 37
21.284± 20.221
P= 0.000 n= 37
32.568± 22.310
P= 0.001 n= 37
32.361± 20.870
P= 0.011 n= 36
17.355± 27.730
P= 0.000 n= 31
Plant
Species
Count
3.216 ± 1.988
P= 0.001 n= 37
12.405 ± 4.220
P= 0.008 n= 37
7.541 ± 2.864
P= 0.141 n= 37
3.167 ± 1.363
P= 0.021 n= 36
4.290 ± 2.673
P= 0.020 n= 31
Average
Girth
1.032 ± 0.311
P= 0.168 n= 37
0.938 ± 0.311
P= 0.296 n= 37
0.275 ± 0.180
P= 0.065 n= 37
0.157 ± 0.192
P= 0.000 n= 36
0.841 ± 0.737
P= 0.005 n= 37
Table 1. Mean frequency count per variable for each habitat. P = Shapiro-Wilks normality P value
Table 1 identifies initial observations of highest bird species count (species richness) in the Laurel forest and lowest
species richness on Mount Teide. The highest endemic bird count was within the Laurel forest and the lowest was
within the Mediterranean scrubland of Arona. The highest individual bird count was within the Laurel forest and
lowest individual bird count on Mount Teide. The highest percentage ground cover was within the Mediterranean
scrubland of Arona and the lowest was within the Pinus canariensis forest. The highest plant species count was
within the Laurel forest and the lowest was within Mount Teide. The highest average girth (Biomass) was within
the Pinus canariensis forest and the lowest was within Mount Teide. Due to high standard deviation as a result of a
high zero data entries (as a result of no bird sightings or no plant growth) more analysis is required before accurate
conclusions can be gained from this data.
Habitat Code
Birds observed 1 2 3 4 5
No. Endemic Species 3 2 4 3 2
No. Species 6 5 10 6 9
No. Species specific to habitat 3 1 4 2 2
Table 2. Total endemic birdspecies count per habitat,total birdspecies count per habitat and total identified bird species specific to the habitat they were
observed in.
Table 2 shows that the Mediterranean scrubland of Arona had the highest total species richness with the highest
total endemic species and species only occurring within that habitat. Comparatively to table 1, the Mediterranean
scrubland is more biodiverse however the frequency in which
the birds identified occurred, was fewer but in larger number;
thus the average was reduced as per the results demonstrated in
table 1. The laurel forest had the fewest number of species and
least number of endemics.
A Kruskal-wallis test identified that there is a significant
difference in bird species richness between habitats by
producing a P value of >0.000. This means that the null
hypothesis of “there is no difference in number of bird species
between habitats” should be rejected and the Ha of “there is a
Figure 1. Average birdspecies count across each habitat

4. difference in the number of bird species between habitats” should be accepted. Figure 1 shows the Laurel forest has
the highest average bird species, which supports the alternative hypothesis.
A Spearman’s rank correlation was performed to determine any relationships between bird species count (species
richness), endemic bird species and the measured habitat characteristics. The following significant positive
coefficient correlations were produced:
Bird species richness
- Plant species count (species richness) P = 0.279
- Average girth (Biomass) P = 0.353
Endemic bird species
- Bird species count (species richness) P = 0.590
- Individual bird count P = 0.582
- Average girth (biomass) P = 0.251
The findings from the correlation analysis show that as plant species richness increases, so too does bird species
richness. This is shown in figure 3. In addition, as bird species richness increases, so too does endemic bird species
richness. The positive correlation between average girth (biomass) and both overall bird species richness and
endemic species richness, indicates that as biomass increases, so too does bird species richness and endemic bird
species richness. This is shown in figure 2 for bird species richness. Though there was a small indication of a
correlation between bird species richness and percentage ground cover, it was of enough significance to be a
confirmed coefficient correlation.
Discussion:
Findings from this investigation have identified that across the island of Tenerife, specifically with in the habitats
tested; the null hypothesis stating that “there is no relationship between bird species richness, plant species richness
and biomass” should be rejected and the alternative hypothesis (Ha) of “there is a relationship between bird species
richness, plant species richness and biomass” should be accepted. The observed correlations means that as biomass
and plant species richness increases so too does bird species richness. Though endemic bird species do not have a
significant correlation with habitat characteristics other than biomass abundance, the significant positive correlation
with bird species richness is an indication that investment in overall bird species richness conservation is of benefit
to endemic bird species as well.
Of the bird species observed, to bird species were present in all or most of the tested habitats. The African blue tit
and Canary island Canary were present in multiple habitats demonstrating a robust niche selection. However the
species with the most limited niche selection and subsequently restricted range, was the Blue Chaffinch which only
occurred in the pine forest. These findings support the theory of ecological release (Bolnick et al. 2010) identifying
that both the African blue tit and Canary island Canary have alleviated interspecific competition for niche selection
by adapting to occupy a broader range of niches. On the mainland the African blue to is found predominantly
within dense forest vegetation, however within Tenerife it was identified within four comparatively different
habitats.
Figure 2. Birdspecies count (Species richness) across all average girth(m)
(Biomass)
Figure 3. Birdspecies count (Species richness) across plant species count
(plant species richness)

5. The absence of the laurel pigeon within the assessment of the Laurel Forest is of significant interest. Its absence
could be attributed to a number of factors outlined by this study. Though the total number of endemic species
recorded within the Laurel Forest was two, there was a significant number of nonendemic species which could be
an indication that the laurel pigeon may have been dislodged from its niche by interspecific competition or it may
have experienced ecological release. Recommendations for conservation efforts towards the protection of the laurel
pigeon include increased plant species richness and biomass to encourage an increase of bird species richness
which should in turn increase endemic species richness. The same conservation efforts could be applied to the
conservation of the blue chaffinch to ensure an increase in population.
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