Tag Archives: Masked Lapwing

Weekdays Outing to Lysterfield Lake Park

4 July 2022

Photographs by Steve Hoptroff

Grey Butcherbird

Skies were blue and the air was calm so conditions for birding looked very favourable as 13 people met in the car park near the start of the Lake Circuit Track. Our leader was Rob Grosvenor who had visited the area many times over the past years. He could advise on likely locations for the different species.

White-eared Honeyeater
Yellow-faced Honeyeater

Initial walking was northerly in the bush. It was cold – see the weather conditions – and birds
were not overactive though Grey Fantails maneuvered acrobatically for insects near the tree
canopies. Spotted Pardalotes called unseen and the honeyeaters observed were the White-eared, Eastern Spinebill, Red Wattlebird and that so-familiar Noisy Miner. No blossom was seen.

Grey Shrike-thrush

Superb Fairy-wrens were active at the edges of the track and Red-browed Finches seemed to accompany Brown Thornbills foraging while Silvereyes moved about in small flocks. Good sightings of Golden Whistlers brought smiles to the observers. Around the lake waterbirds predominated. Musk Duck males were making the splashing display which seems to be visible over quite a distance.

Musk Duck, male

The females/ immature males were taking no apparent notice but formed small groups or couples at a distance. Eurasian Coots were the most numerous but were travelling to different spots around the lake so not always obvious.

Masked Lapwing

On the shore there were Masked Lapwing, Australian Wood Duck and Purple Swamphen with Dusky Moorhen and Pacific Black Duck dividing their time between shore and water. Grebes were mostly the Hoary-headed species in flocks and Little Pied and Little Black Cormorants rested on the marker buoys.

Hoary-headed Grebe

The only raptor observed was a Swamp Harrier and the only parrots were Rainbow Lorikeets, Crimson Rosellas and brief views of an Eastern Rosella. No cockatoos were detected.

Swamp Harrier
Crimson Rosella

The highlight for many of us was the observation of Common Bronzewing near the park entrance and the subsequent sighting of a male Brush Bronzewing as we descended
the hill towards the cars.

Common Bronzewing, male

By walk’s end we recorded 42 species (later adjusted to 43 with the addition of a pair of Black Swans). Our heartfelt thanks to Rob for sharing his knowledge of the area.
Diane Tweeddale coordinator BirdLife Melbourne weekday outings

Beginners outing to The Briars

28 May 2022

Leaders: Hazel and Alan Veevers

Species Count: 47

The 23 members gathered near the Visitor Centre were pleased to see a variety of birds before starting the Sanctuary walk. These included Eastern Rosella, Grey Butcherbird, Masked Lapwing, Purple Swamphen and King Parrot.

Masked Lapwing. Photo by Eleanor Dilley
Purple Swamphen. Photo by Eleanor Dilley

Soon after starting off along the boardwalk a Great Egret was spotted preening in a nearby dead tree, thus providing a good opportunity for photographers. From the first hide a pair of Black Swans and a Yellow-billed Spoonbill were found on the water. 

Great Egret. Photo by Eleanor Dilley
Yellow-billed Spoonbill. Photo by Eleanor Dilley

Continuing along the boardwalk a number of bushbirds showed themselves, including Superb Fairy-wrens, Silvereyes, Yellow-faced Honeyeaters and two Golden Whistlers. From the large hide there were great views of another Yellow-billed Spoonbill as it foraged for food close to the window. A White-faced Heron flew in, landing nearby, and a pair of Pacific Black Ducks swam nonchalantly across the field of view. 

White-faced Heron. Photo by Eleanor Dilley
Black-fronted Dotterel. Photo by Alan Veevers

On leaving the hide some of the first group were fortunate to see a male Mistletoebird fly overhead, while those who lingered in the hide saw a pair of Black-fronted Dotterels fly in. Continuing along the boardwalk a Swamp Wallaby was seen feeding beside the track whilst more Superb Fairy-wrens busied themselves finding food. A White-eared Honeyeater showed itself as it foraged in the outer foliage of a flowering eucalyptus tree. 

Swamp Wallaby. Photo by Eleanor Dilley
White-eared Honeyeater. Photo by Eleanor Dilley

A flock of Little Corellas was seen, and heard, flying past the lookout overlooking the wetlands. As we walked along the high part of the track, Noisy Miners and Rainbow Lorikeets were the dominant species, though a pair of Long-billed Corellas and some Galahs were seen in a distant tree. A pair of Australian Pelicans flying gracefully in formation overhead were a delight to see. On the descent towards the creek New Holland Honeyeaters, Grey Fantails and Dusky Moorhens were sighted.

At lunch, back in the picnic area, the sun appeared and highlighted the colourful plumage of the many Crested Pigeons that foraged underfoot. Most of the members stayed for the afternoon walk up the hill towards the old homestead. Species seen here included Australian Wood Ducks, Sulphur-crested Cockatoos, Spotted Doves and lots more Crested Pigeons. The heritage chickens and pigs were admired along with the vast plantings of heritage fruit and vegetable species.  A distant raptor created a lot of interest and, after examining photographs, it was positively identified as a Brown Goshawk.

Crested Pigeon. Photo by Eleanor Dilley
Tawny Frogmouths. Photo by Alan Veevers

On returning to the carpark a few members decided to revisit the first section of the wetlands walk and, following a tip-off from a Ranger, found 3 Tawny Frogmouths high up in a tree near the first hide.

A total of 47 species were recorded for the day which was deemed to be excellent for the time of year.

Thanks once again to Eleanor Dilley who provided all but two of the above photos and also for those used to verify the Brown Goshawk sighting.

Beginners Outing to Lillydale Lake

28 July 2018
Leaders: Hazel and Alan Veevers; Species Count: 49

Little Pied Cormorant, Lillydale Lake
Little Pied Cormorant. Photo by Eleanor Dilley

Thirty-one members gathered by the lake in perfect weather for bird-watching – sunshine and very little wind. Water birds were plentiful with many Eurasian Coots, Purple Swamphens, Dusky Moorhens, and lots of Australasian Darters.

Pink-eared Duck, Lillydale Lake
Pink-eared Ducks. Photo by Eleanor Dilley

Unfortunately the wetlands boardwalk was closed for repair, but from the track around the outside of it there were good views of Little Pied and Little Black Cormorants as well as a pair of Pink-eared Ducks.

Little Pied Cormorant with fish - Bevan Hood
Little Pied Cormorant with fish. Photo by Bevan Hood

Little Black Cormorant, Lillydale Lake
Little Black Cormorant. Photo by Eleanor Dilley

On some rocks alongside the lake, a young Darter was wrestling with a huge fish, desperately trying to manipulate it into a swallowing position.

Australasian Darter with fish, Lillydale Lake
Australasian Darter with fish. Photo by Eleanor Dilley

Two Whistling Kites circling overhead provided close-up views for the beginners but were the only raptors seen all day.

Whistling Kite, Lillydale Lake
Whistling Kite. Photo by Eleanor Dilley

It was pleasing to see family groups of Superb Fairy-wrens in many different locations on the route away from the lake towards Hull Road wetlands. Despite everyone’s best efforts, none of the expected Tawny Frogmouths could be found in that area.

Golden Whistler (F), Lillydale Lake
Golden Whistler (f). Photo by Eleanor Dilley

However, Golden Whistler, Grey Shrike-thrush, King Parrots, Rainbow Lorikeets, Eastern Spinebills, as well as White-plumed and New Holland Honeyeaters, were seen.

Rainbow Lorikeet, Lillydale Lake
Rainbow Lorikeet. Photo by Eleanor Dilley

The Hull Road Wetlands contained plenty of water but very few birds, though an Eastern Yellow Robin and Crimson Rosellas were spotted in the surrounding trees.

Grey Teal - Eleanor Dilley
Grey Teal. Photo by Eleanor Dilley

Both Grey and Chestnut Teal were also found but only two and four, respectively, of each species. Returning to the carpark, two White-faced Herons were feeding in a small pond.

White-faced Herons, Lillydale Lake
White-faced Herons. Photo by Eleanor Dilley

After lunch a short walk was taken beside the lake. A lone Masked Lapwing stood on the beach, seemingly minding its own business as we walked by.

Masked Lapwing - Bevan Hood
Masked Lapwing. Photo by Bevan Hood

Members stood for a while on a look-out platform enjoying the sight of an Australasian Darter swimming and diving for fish, clearly demonstrating how it got the nickname “snake bird”. A Grey Butcherbird, perched obligingly close to the group, gave the photographers an ideal opportunity for a photo.

Grey Butcherbird - Bevan Hood
Grey Butcherbird. Photo by Bevan Hood

Heading back over the hill members paused to admire the distant view towards the Dandenong Ranges before returning to the car park. A very pleasant outing ended with a tally of 49 species.

View the complete bird list for the day: BM Jul 2018 Bird List Lillydale Lake

Weekday outing to Point Cook Coastal Park

14 March 2018

Cormorants and Gull - Bevan Hood
Little Pied Cormorant, Pied Cormorant, Silver Gull. Photo by Bevan Hood

Overcast and mild weather greeted 21 birdwatchers from many areas of Victoria as we assembled in the Beach Picnic area car park. Alan and Hazel Veevers were our leaders and the car park soon added Superb Fairy-wren, New Holland Honeyeater and Red Wattlebird to the Common Starlings, Australian Magpies and Willie Wagtails most had noted on their drive in.

This slideshow requires JavaScript.

Time and tide wait for no bird watcher so we immediately drove to the homestead car park and walked through the pine trees to the beach. Highlights here were Zebra Finches near the fence line and an obligingly perched Brown Falcon which gave photographers very good views.

This slideshow requires JavaScript.

Galahs, Little Ravens and Crested Pigeons were also noted here and the squeals from a windmill were initially confusing till the machinery was noted among some trees. No birds really make that noise.

Low tide at the beach saw a flock of Chestnut Teal, many Silver Gulls and Crested Terns and the occasional Pacific Black Duck and Pacific Gull perched on the exposed rocks.

Farther along we encountered Pied and Little Pied Cormorants which enabled people to compare the sizes and markings for future identification.

This slideshow requires JavaScript.

Heading back to the cars prior to lunch Black-shouldered Kite and Nankeen Kestrel were added to our growing raptor list which also had couples of Whistling Kites and Black Kites seen earlier.

Black Kite - Bevan Hood
Black Kite. Photo by Bevan Hood

A brief stop at the water control area of a housing estate added Dusky Moorhen and Purple Swamphen. One of the swamphens caused some excitement when it appeared to be eating a yabby but closer inspection showed ‘lunch’ to be the rhizome of one of the water plants, complete with apparent ‘legs’.

This slideshow requires JavaScript.

Our lunch was accompanied by several optimistic magpies and enlivened by fairy-wrens in great numbers foraging low around us. The magpies moved out and an enormous racket drew our attention to their mobbing of a raptor. It was only slightly larger than the magpies but they had the numbers and the raptor departed. Much discussion about its identity followed but no one had managed a clear view. The ID came later after photos had been closely examined – the wings and tail were those of a Brown Goshawk. Cameras now freeze action much better than human vision.

Brown Goshawk - Danika Sanderson
Brown Goshawk

After lunch we walked beside the beach. Initially there were only a few fairy-wrens foraging among the seaweed but carefully continuing south we encountered more gulls, teal and terns roosting on the exposed rocks close to shore. Scanning yielded two Musk Ducks swimming beyond the crowd and then a rather unexpected sighting – an immature Australasian Gannet resting on one of the rocks.

Gannet - Gull - Tern - Bevan Hood
Australasian Gannet, Silver Gull, Crested Tern. Photo by Bevan Hood

White-faced Heron and Australian White Ibis were also present in small numbers and a few Grey Teal were swimming together in one area. Back through the scrub where Grey Fantails dominated sightings and then on to a new wetland near the RAAF Lake car park. Expectations may have been low as we approached it but soon “grebes” were called.

This slideshow requires JavaScript.

Both Australasian and Hoary-Headed were present and diving out of sight as grebes are wont to do. The omnipresent Chestnut Teal were noted, plus a couple of Pacific Black Ducks and then there were the dotterels on the further, smaller lake.

This slideshow requires JavaScript.

Both Black-fronted and Red-kneed Dotterel were there and a pair of the latter were engaging in a bobbing display to each other. The edges of the reed beds housed Australian Reed-Warblers (silent at this time of the year) and Golden-headed Cisticolas perching on seed heads and making their buzzing call.

This slideshow requires JavaScript.

Leaving this area with regret we gathered for bird call. Total species count was 56, very creditable for an area which is being surrounded more and more closely by housing. We thanked Hazel and Alan enthusiastically for all their preparation and care which had given us such a good day’s birding.

 

Diane Tweeddale, coordinator BirdLife Melbourne weekdays outing

Beginners Outing to Lysterfield Lake

23 July 2017
Leader: Robert Grosvenor; Species Count: 45

Golden Whistler (M), Lysterfield Lake
Golden Whistler, male. Photograph by Eleanor Dilley

Twenty eight hardy birders braved the very strong and cold wind to attend the beginners outing at Lysterfield Lake.

Magpie-lark (M), Lysterfield Lake - Dilley
Magpie-lark, male. Photograph by Eleonor Dilley

While waiting for all attendees ,Crimson and Eastern Rosellas, Purple Swamp Hen, Magpie-lark and Rainbow Lorikeets were viewed in the carpark. A Masked Lapwing was spotted closer to the Lake’s edge.

Masked Lapwing Lysterfield 2017 07 22 1588 800x944 M Serong
Masked Lapwing. Photograph by Merrilyn Serong

On the reccie more Kangaroos were seen than birds and it looked like this outing would be more of the same as the first twenty minutes went by before we sighted our first bird – a Brown Thornbill, quickly followed by a White-eared Honeyeater.

Eastern Grey Kangaroo joey Lysterfield 2017 07 22 1468 800x1067 M Serong
Eastern Grey joey. Photograph by Merrilyn Serong

There were long periods of inactivity until we would come upon a small hot spot. The first of which produced excellent sightings of Grey Shrike-thrush, Grey Fantail, both male and female Golden Whistlers and the two birds of the walk, a male Rose Robin and a Brush Bronzewing.

Unfortunately not all the beginners were able to see both. The Rose Robin surprised everyone when it appeared in a tree at eye level not more than two metres in front of us but did not stay for long. Still, many of the group got their first look at this beautiful bird. The Bronzewing skulked in the undergrowth, making sighting difficult before it was disturbed and flew off.

Little Pied Cormorant Lysterfield 2017 07 22 1513 800x836 M Serong
Little Pied Cormorant. Photograph by Merrilyn Serong

The strong wind was keeping the small birds hidden but in a more protected spot we found Superb Fairy-wren, Silvereye and Spotted Pardalote.

Venturing down to the edge of the lake enabled us to see Musk Duck, Hoary-headed Grebe, Hardhead and Coot all on the water, before returning to the main track.

Little Black Cormorant Lysterfield 2017 07 22 1516 800x704 M Serong
Little Black Cormorant. Photograph by Merrilyn Serong

Again there was a long period of inactivity with only a Grey Butcherbird heard and a Little Raven overhead. We were now back at the lake wall where Little Pied and Little Black Cormorants, Australasian Grebe and Dusky Moorhen were seen.

With the wind howling across the lake we were all glad to break for lunch and find an area out of the wind to partake of some refreshments.

After lunch we walked to the eastern end of the carpark and a short distance along the Logan track. In the more open fields we saw Straw-necked  and White Ibis, Wood Duck, Cattle Egret and in the distance a few Red-rumped Parrots.

Common Bronzewing (F), Lysterfield Lake
Common Bronzewing. Photograph by Eleanor Dilley

Returning to the carpark we had excellent views of another Brush Bronzewing together with a number of common Bronzewings.

Brush Bronzewing (M), Lysterfield Lake
Brush Bronzewing. Photograph by Eleanor Dilley

Overall 45 species were seen for the day which, considering the wintery conditions, was noteworthy.

See the complete bird list for the outing: BM July 2017 Bird List Lysterfield Lake

 

 

 

Beginners Outing to The Briars

28 May 2016
Leaders: Hazel and Alan Veevers
Species count: 50

Thirty-three members gathered at the Visitor Centre in overcast conditions and entered the wildlife enclosure where a female Golden Whistler, a Grey Fantail and Brown Thornbills were seen just inside the gate. From the bird hides several species were recorded, including Hoary-headed Grebe, Black Swan and White-faced Heron. An Eastern Grey Kangaroo and a Swamp Wallaby added to the interest as the members began the walk up towards the Wetlands Lookout.

Swamp Wallaby AV Briars 2016
Swamp Wallaby. Photo by Alan Veevers.

Swamp Gums were flowering alongside the track which attracted several species of Honeyeater, including Yellow-faced, White-eared and New Holland, as well as Red and Little Wattlebirds. Unfortunately rain started to fall heavily as the group followed the Woodland Walk. Few birds were seen until a lone (captive) Emu was spotted as we approached the gate leading back to the car park.

Emu AV Briars 2016
Emu. Photo by Alan Veevers.

 

An early lunch was taken under the veranda outside the Visitor Centre, during which the rain-clouds cleared, giving way to some welcome sunshine. Noisy Miners were evidently very interested in our food but a pair of Masked Lapwings took no notice whatsoever and continued their foraging in the adjacent paddock.

Noisy Miner The Briars 2016 05 28 0482 800 M Serong
Noisy Miner. Photo by Merrilyn Serong.

Masked Lapwing The Briars 2016 05 28 0556 800 M Serong
Masked Lapwing. Photo by Merrilyn Serong.

Afterwards, the group walked up towards the old homestead where several Parrot species were observed at close quarters. Eastern Rosellas and Rainbow Lorikeets were the most colourful, enhanced by the bright sunlight. Walking along the Farmland Track members were entertained by two litters of young free-range piglets which came rushing up to the fence. Shortly afterwards a Black-shouldered Kite was seen perched on a nearby dead tree, enabling everyone to get a good look.

Rainbow Lorikeet The Briars 2016 05 28 0420 800 M Serong
Rainbow Lorikeet. Photo by Merrilyn Serong.

After returning to the car park another track was taken alongside Balcombe Creek, where a pair of Eastern Yellow Robins provided members with a great view as they repeatedly darted from the shrubs to the path for food. A Grey Shrike-thrush, a Common Bronzewing and Numerous Superb Fairy-wrens were amongst other birds seen on this final walk.

Pig The Briars 2016 05 28 0461 800x600 M Serong
Free range piglet. Photo by Merrilyn Serong.

The day’s tally was a creditable 50 species (not counting the Emu), which was felt to be very good for an excursion at this time of year in less than perfect weather conditions.

View the bird list for the outing: BM May 2016 Bird List The Briars

 

Weekdays outing to Reef Island

2 March 2016

Reef Island beyond the swans
Reef Island beyond the swans. Photograph by Diane Tweeddale

The forecast of a day of 30o did not deter 23 bird watchers from meeting. Our leader was Bill Ramsay whose timing ensured that a falling tide allowed us to walk out along the causeway to the island almost dry shod. The car park sounded with calls of wattlebird and raven while Black Swans paddled by in small groups, apparently unfazed by the early morning salt water exercising of horses from the near horse farms. The beach north of the car park was noteworthy for the crowd of about 100 Masked Lapwings which vastly outnumbered the few Silver Gulls.

The beach section of the walk to Reef Island
The beach section of the walk to Reef Island. Photograph by Margaret Bosworth

We concentrated on the beach but the adjacent heathy grassland sounded occasionally to calls of Superb Fairy-wren, Australian Raven and Striated Fieldwren. A young Black-shouldered Kite perched distantly on a dead tree and a male and female White-fronted Chat foraged at the upper end of the beach. Walking was variable and more challenging when we reached the rockier sections. The vegetation was interesting with sea grass draping the lower sections of the mangroves and salt bushes. Near the causeway Black Swans congregated, at least 100 of them in the shallows. Distant views of a pair of Australian Pied Oystercatchers and a solitary Eastern Curlew took some work.

Heading out along the causeway - Bosworth
Heading out along the causeway. Photograph by Margaret Bosworth

As we reached promising areas we added Little Pied, Little Black and Pied Cormorants with list highlights of Great Egret, Royal Spoonbill and Pacific Gull. Then we reached areas of shallow ponds and waders. Scopes up again! Double-banded Plover, Sharp-tailed Sandpiper and Red-necked Stint came first and then Red-capped Plover and Curlew Sandpiper were added later.

Pacific Gull
Pacific Gull. Photograph by Margaret Bosworth

Much discussion occurred over the identification of a godwit but eventually the bird changed position and a confident call of ‘Bar-tailed Godwit’ rang out. Out to the end where we were delighted by a flock of about 20 Pacific Golden Plovers (a few in traces of breeding plumage) and about 20 Ruddy Turnstones with a solitary Grey-tailed Tattler perched on a rock at water’s edge.

Lunchbreak
Lunchbreak. Photograph by Diane Tweeddale

Lunch seated on driftwood or seagrass drifts was a welcome relaxation and then the party divided into the northern ‘rockhoppers’ and the southern ‘gentle walkers’. The former did not add more species but the ‘gentlefolks’ succeeded in locating a previously elusive Red-capped Plover definitively. Not an addition to the group list but personally satisfying to those who’d missed it before. A welcome cool breeze rose about 1pm and fanned hot brows on the return walk. Back at the cars a few departed but most stayed on for bird call where a gratifying total of 45 species was recorded. Not only the total but the composition was much appreciated and we thanked Bill for his work and preparation which went into this successful day.

Diane Tweeddale, Coordinator BirdLife Melbourne Weekdays outings

Sex ratio variation among the Masked Lapwing

Balwyn meeting report
October 2015
Invited speaker, Daniel Lees reported on his research topic. The following is an abstract of his report.

In the absence of data on sex ratios, conservation managers assume a 1:1 ratio which may not be the case, as males and females may exhibit differential dispersal, mortality, size, feeding behaviour and habitat use. With the appropriate data, management authorities could focus on threats to the limiting sex allowing the implementation of more successful management strategies (predator control, sign posting, exclusion zones and education)

In this study we examine whether sex-ratio variation is occurring in the Masked Lapwing Vanellus miles at the primary, secondary or tertiary level.

We radio-tracked 50 masked lapwing Vanellus miles chicks (50 broods) and compared body condition (growth rates; grams per day) and mortality (whether the male chicks were more or less likely to perish than female chicks) We also compared the body condition of all chicks within broods and to establish whether the time of the breeding season affects the brood sex ratio.

Chicks were no more or less likely to be male (or female) as the breeding season progressed. Male radio-tagged chicks (n = 27) were no more or less likely to perish when compared to female radio-tagged chicks (n = 21). At hatching, male chicks were no lighter or heavier nor had shorter or longer tarsi than female chicks Male chicks also grew no faster or slower when compared to female chicks.

This study detected no sex ratio variation or sex-biased survival among broods in the sexually monomorphic Masked Lapwing. This result was as expected and is in line with the Trivers and Willard (1973) hypothesis and the literature which details such variation exclusively among sexually dimorphic species.

Sex ratio variation among the Masked Lapwing

Monitoring survival of free-living precocial avian young is difficult. Perhaps the most promising methods available to determine survival are: (a) a combination of radio-tracking and frequent investigator brood visits or (b) targeted visits timed to mark young after hatching and then again to confirm fledging.

Our aim is to understand if the process of radio-tracking and the associated frequent visits negatively impact chicks when compared to infrequent targeted monitoring visits.

We radio-tracked 50 masked lapwing Vanellus miles chicks and compared body condition (scaled mass index) and within-brood mortality to examine whether attached radio transmitters influenced chick body condition or survival. We also compared the body condition of all chicks from radio-tracked broods to chicks subjected to targeted monitoring to examine whether investigator visits influenced body condition.

Within broods, there was no difference in body condition or mortality between chicks with and without radio-transmitters. Similarly, there was no difference in body condition between broods subject to radio tracking or targeted monitoring.

In agreement with the literature on the ‘glue on’ method of backpack radio-transmitter attachment, the body condition of lapwing chicks was not affected by radio-tracking compared with the targeted monitoring technique. Smaller, less robust and possibly less habituated species may still be negatively affected by radio-tracking. Radio-tracking seems an ethical and practical method for attaining an improved understanding of cryptic life history stages such as chick-rearing in shorebirds.

Note

A Scaled Mass Index (SMI; a mass length relationship; Peig and Green 2009) was used to characterise body condition. All statistical tests were conducted in R (2015) with GLMMs of body condition conducted using the package ‘nlme’ (Pinheiro et al. 2014) and the Cox proportional hazard regression was conducted in the package ‘survival’ (Therneau 2015).

Peig, J. and Green, A. J. (2009). New perspectives for estimating body condition from mass/length data: the scaled mass index as an alternative method. Oikos 118, 1883-1891. doi: 10.1111/j.1600-0706.2009.17643.x.

Pinheiro, J., Bates, D., DebRoy, S. S., Sarkar, D., and Team, R. D. C. (2014). Nlme: Linear and nonlinear mixed effects models. (R Foundation for Statistical Computing.)

Team, R. D. C. (2015). R: A language and environment for statistical computing. (R Foundation for Statistical Computing: Vienna, Austria.)

Therneau, T. M. (2015). A package for survival analysis in R.

Trivers, R. L. and Willard, D. E. (1973). Natural Selection of Parental Ability to Vary the Sex Ratio of Offspring. Science 179, 90-92. doi: 10.1126/science.179.4068.90.