Building Bat Boxes

By John Tyne (Parks and Wildlife Commission NT)

John Tyne (Parks and Wildlife Commission NT) and Erin Westerhuis (Charles Darwin University) gave an excellent presentation and workshop on bat boxes at the Land for Wildlife birthday event recently. Here, John gives some hints and tips on how to create bat boxes of your own.

Thanks for your interest in the bat boxes that I was showing on Saturday!

Parks and Wildlife Commission NT’s John Tyne and Erin Westerhuis presented a bat box building workshop to the Land for Wildlife and Garden for Wildlife members at the recent birthday event. (Image B. Low)

The bat boxes I built were all made from one plank of untreated softwood timber. To make one of the smaller boxes, you’ll need approximately 1.5 m of timber that is 190 mm wide and 45 mm thick. I was able to find a piece like this at the Home Hardware shop in town. I used 70mm long exterior timber screws to piece it all together.

The back piece 350 mm long x 190 mm wide x 45 mm thick
The front piece 200 mm long x 190 mm wide x 45 mm thick
Two side pieces 200 mm long x 190 mm wide x 45 mm thick
The roof piece 380 mm long x 190 mm wide x 45 mm thick
The base/floor 100 mm long x 170 mm wide x 45 mm thick

(this is the only piece that isn’t 190 mm wide!)

Two spacers for back: 50 mm long x 190 mm wide x 45 mm thick

(these are to put on the back of the box so when you hang it is off the tree/post a little ways)

On the inside I used a staple gun to put up some old shade cloth. Instead of shade cloth you could score lines into the back so that the bats are able to climb it more easily. On the extension out the bottom that the bats will have to land on to climb up, I scored the timber using a hand saw. You could also put shade cloth on this instead. The gap at the base should be around 20 mm wide to allow the bats to climb in. On the boxes I made, I put an exterior grade metal hinge and two magnetic clasps on the lid so that I could open it. You could simplify things by just fixing the lid down with screws and not using a hinge. Depending on where you hang it, you could just screw it straight to an object (shed/post), or you could strap it to a tree. Try and hang the box at least 3 meters high, in a sheltered area but with a clear flight path to the box entry.

Bat Box Design (Image R. Ferrari).

Good luck putting this together, and let me know if you have some success with bats moving in. Any questions feel free to ask!

~ John Tyne

Build bat boxes to install on your property and provide them with a safe space by following John Tyne’s helpful instructions. You can also download some fact sheets that were provided by the crew on the day, including Boxes for Bats and also the Bat Roost Box Kit.

The Structure and Insulation of Avian Nests

Birds’ nests have evolved into many shapes and sizes, but they all function to provide a secure substrate for eggs and hatchlings, camouflage and defence from predators, as well as protect the eggs, hatchlings and incubating parent from harsh climatic conditions. My doctoral studies focused on understanding the factors influencing the structure and insulation of avian nests and hence the manner in which a nest may influence the energetic cost of incubation.

Nest materials can range from natural plant items (sticks and grass) and organic material (mud), to animal materials (hair, fur, spider silk) and man-made items (wool, wire and cloth). This nest is made completely from horse hair and a few strands of grass.

FACTORS INFLUENCING NEST SIZE AND SHAPE

Parent mass

Comparing the size and shape of nests of 36 Australian passerine species against parent mass reveals that nest surface area increases in direct proportion to the size of the parent. Nest diameter and height increase with parent mass but as nests become larger in line with increases in parent mass, the nest cup also becomes shallower and the opening becomes wider than expected, which allows for the space that the chicks will occupy.

Nest mass increases with parent mass at a rate that matches that of a supporting structure, suggesting that structural considerations of nest construction are of primary importance to nest design. The requirement for structural support is also evident for nest thickness, which increases more than proportionally expected as parent size increases. Structurally adequate nests become thicker than expected for their size in larger birds.

The clutch

Of interest is how the size or number of eggs in a clutch relates to the size of a nest. The clutch surface area and the internal surface area of the nest increase simultaneously; and the clutch volume and volume of the nest cup are also associated. Since nest design for the majority of birds in the study is in part influenced by the male and egg shape is controlled by muscles in the pelvis of the female, it is likely that one does not control the other. However, nest and egg size/shape are influenced by body size and ancestry. Therefore, it is likely that the nest and clutch are in fact independent, yet matched secondarily due to the shared influence of body mass and genetic ancestry.

The delicate nest of a Singing Honeyeater is decorated with Emu feathers and held together with spider silk and hair.

FACTORS INFLUENCING NEST INSULATION

Nest structure

As we know, the nest surface area increases in proportion to bird size, however nests become much thicker than expected as bird size increases. The thick walls provide structural support for the parent and clutch, with the consequence that structurally adequate nests achieve greater insulation than expected, as they increase in size. Nests are often viewed as objects that are designed to prevent heat loss from the clutch and incubating parent; however the requirement for adequate structural support is the primary selective influence on nest construction, not the requirement for insulation.

Nest microclimate

By assessing the insulation of Spiny-cheeked Honeyeater (Acanthagenys rufogularis) and Yellow-throated Miner (Manorina flavigula) nests under varying wind conditions, I found that wind enters the nest material and dissipates heat, resulting in a decrease in thermal insulation with greater wind speeds. The consequence of increased wind currents around and through the nests would be a near-doubling in heat production required by the parent when incubating.

While ambient temperature does not influence the structure of nests in my study, it does influence the insulation of nests and the thermal efficiency of the material. However, temperature and precipitation (henceforth referred to as climate) act in combination, indicating that the response of Australian passerines to one variable depends upon the level of the other.

 In sites with low temperatures, nest insulation may be important to maintain an appropriate microclimate for offspring and therefore birds construct nests with good insulation, irrespective of the rainfall at the site. For nests constructed in warm climates but at the two extremes of rainfall, there is a pronounced decrease in insulation for nests built in areas with high rainfall, compared to areas with low rainfall.

The effect of climate extends to the thermal efficiency of the nest materials, indicating that not only the ambient temperature, but also the precipitation of the breeding site, influences material selection during the nest construction phase. Birds breeding in warm and wet climates construct their nests with materials that have a poor thermal efficiency compared to those in dry climates. The warm temperatures may cause a relaxation in the need for insulation, and poorly insulating materials (such as sticks and grasses, rather than fur and wool) are possibly less absorptive and able to dry out faster following a rain event, to restore the insulating function of the nest.

To determine the effect of water (from rain, dew or absorption from the nest substrate) on the heat loss from the nest, I measured Tawny-crowned Honeyeater (Gliciphila melanops) nests under varying water content levels (from dry to saturated). Water penetrating the nesting material increases conductance of G. melanops nests by up to two and a half times the rate seen in a dry nest – a consequence of the decreased thermal efficiency of materials in a wet nest. As a result, additional energy is required by the incubating parent to keep clutches warm when nests become wet. Individuals should be capable of obtaining additional floral resources to deal with an energy deficit in cold and wet conditions. However, if floral resources are poor and an individual is unable to meet such energy demands, it may abandon the nest altogether.

Not all nests seem to be sufficient – this nest has large holes but is strong and doesn’t absorb water – but they have functions other than insulation of the young.

SUMMARY

My studies highlight the importance of nest design and construction for the thermal properties of nests – small variations in nest design can have significant impacts on the insulation value of a nest, which will in turn influence the energetic cost of incubation. The effect of rain and wind on nest insulation, and the consequence of this for the energetics of the incubating parent, reinforces the view that appropriate nest site selection that provides additional shelter is crucial for avian reproductive success.

Bird Breeding Bonanza

Many avian species are breeding in town at the moment, with young chicks and fledglings making their way out into the world. Several Masked Lapwing (Vanellus miles) chicks and Black Swan (Cygnus atratus) cygnets have been seen at the Alice Springs sewerage treatment ponds over the last couple of months.

In my own yard, I have had a pair of young Magpie-lark (Grallina cyanoleuca) that recently fledged their sturdy mud nest and the family of four have been busy catching tasty insects in the lawn ever since. There is also a diligent Crested Pigeon (Ocyphaps lophotes) sitting on a nest with its chicks and other young nearby – who look rather gangly and awkward but delightful none the less! The White-plumed Honeyeaters (Lichenostomus penicillatus) reported in the last newsletter are still hanging around and are now just as vocal as their parents, though no doubt they will eventually go off to find their own territory.

What have you got breeding in your area? Send your photos in to share with the members!

Crested Pigeon (Ocyphaps lophotes) fledgling sits nearby the nest for safety.

Crested Pigeon (Ocyphaps lophotes) parent on a nest with two chicks.

 

Crested Pigeon (Ocyphaps lophotes) parent on a nest with two chicks.

Crested Pigeon (Ocyphaps lophotes) fledgling sits nearby the nest for safety.

 

Magpie-larks (Grallina cyanoleuca) getting ready to fledge the nest last month, now free-roaming and learning to feed on their own.

Magpie-larks (Grallina cyanoleuca) getting ready to fledge the nest last month, now free-roaming and learning to feed on their own.

 

Masked Lapwing (Vanellus miles) chick at the Alice Springs sewerage treatment ponds, one of several being guarded diligently by the parents.

Masked Lapwing (Vanellus miles) chick at the Alice Springs sewerage treatment ponds, one of several being guarded diligently by the parents.

Parks and Wildlife NT Lorikeet Survey

By John Tyne

On September 28th, eight volunteers assisted Parks and Wildlife to conduct a census of introduced Rainbow Lorikeets in Alice Springs. The volunteers came from a number of organizations including Birdlife Central Australia, Alice Springs Field Naturalist Club and Land for Wildlife.  Thirty nine locations were surveyed for rainbow lorikeets, with volunteers recording the times, location and number of birds seen and heard at each survey point.  Despite the damp conditions many birds were out and about. After reviewing the data, I would conservatively estimate that there are at least 17 individual birds. The main population of birds appears to be focused in the Gillen area near the local primary school, which then probably disperses throughout Alice Springs during the day to feed. What is especially concerning is that two nesting hollows in the Todd River and a third in town are currently being used which may indicate an imminent increase in bird numbers.  I would like to thank everyone very much for their help with this survey, and please keep the sightings coming in!  They can be submitted to the NT Wildwatch website (http://root.ala.org.au/bdrs-core/nt-dlrm/home.htm), E-bird (http://ebird.org/content/ebird/) or submitted to me directly (John Tyne, John.Tyne@nt.gov.au ).

~ John Tyne, Parks and Wildlife NT

Survey map of the locations where lorikeets were and were not observed (Map provided by John Tyne).

Survey map of the locations where lorikeets were and were not observed (Map provided by John Tyne). Click on image to enlarge for ease of viewing numbers.

Air Bee n Bee: Creating Hotels for Native Pollinators

Spring is here and gardens are a buzz! Insects play an important role in the environment as pollinators and nutrient recyclers. While it is easy to get carried away with the huge role that introduced European Honeybees (Apis mellifera) play in pollinating crops, there are many more species of native solitary bees (harmless and non-aggressive) that play a very active role in pollinating flowers. Not to mention the ants, butterflies, beetles and other invertebrates that are responsible for pollination. Attracting these critters not only increases biodiversity in your yard, but they will help to keep unwanted insects away.

When the rain comes and you feel the need for a vacation, you might book a hotel to stay in or organise accommodation on Airbnb. But what about the insects? Where do they go when it gets cold and wet? Many insects hunker down when it’s raining and lay eggs in safe, dry places. But many town yards are kept tidy and the lack of debris can mean that there are fewer places for insects to take refuge and lay eggs. An insect hotel can be the key to giving the native insects a helping hand. What about an Air Bee n Bee?!

While spring is here and you’re seeing insects active in your yard, use the warm weather to build an insect hotel ready for the next rains. Insects will use the hollows created to lay eggs, which will hatch in the next round of warm weather. It’s best to place the insect hotel in a dry place with protection from cold winds (a sheltered spot under the house, in front of a window). Ideally, the insect hotel opening of the hotel should be facing north or north-east with exposure to the sun, as it’s unlikely to be successful if placed in the shade. Finally, it should be firmly fixed so that it doesn’t sway in the wind.

You can use smooth (splinter-free), cylindrical spaces from a variety of materials, ranging in size from 3mm holes to 13mm holes (most commonly used around 5-6.5mm) and depths of 70mm to 150mm (according to Tim Heard, author of The Australian Native Bee Book, available at Red Kangaroo Books). A variety of sizes and shapes will cater to different insects and scattering a couple of small insect hotels around the property will increase your chances of providing for competing insects.

Materials used can include bamboo segments, holes drilled into solid untreated wood cubes, hose, paper straws, seed pods or rolls of cardboard. A length of polypipe filled with clay can attract insects that would normally burrow in the ground, which includes over half of Australia’s bee species. The items can be stacked in an empty wooden box or tied together with a sloping roof to keep the hotel dry. Ensure that it has a backing so that it doesn’t turn into an open-ended wind tunnel. You can place a strip of chicken mesh over the front of the insect hotel if you wish to protect the larvae from birds without deterring the hotel guests. The insect hotel can be decorated with old metal for a rustic style or shiny items for that bit of extra ‘bling’. Use anything that you find (recycled items are free or very cheap!), there is no standard design and you are only limited by your imagination!

This time next year when the hotel apartments are emptying out, you can report sightings of your insect guests on Bowerbird and have them identified. Once the insect hotel is vacant again, maintain it by cleaning out any used cells and replace parts if fungus moulds develop. Check out the Valley Bees factsheet for more information on creating an insect hotel.

If you don’t have the capacity to make in insect hotel for your town block, you can provide natural homes for insects by retaining some leaf litter, planting local native trees that produce peeling bark and leave dead branches in situ.

Insect hotels provide sheltered nooks for insects to lay their eggs (Image Wikipedia commons).

Insect hotels provide sheltered nooks for insects to lay their eggs (Image Wikipedia commons).

Video: Red-capped Robin

The Red-capped Robin (Petroica goodenovii) is a gorgeous little bird that can be found through much of semi-arid and temperate Australia within woodland habitats. A juvenile and two adults was snapped by the Land for Wildlife coordinator at Newhaven Wildlife Sanctuary, while on a trip with the Alice Springs Field Naturalists Club last month.

The Red-capped Robin breeding season extends from June to January each year, with females producing two to three small eggs, which are incubated over a 14-day period. Breeding territories are established and defenced by the male, who also feeds the female during the nest construction and incubation process. While the female takes the sole responsibility of incubating, the male assists with feeding the young.

The juvenile in the video sat quietly for some time calling for food and ate enthusiastically when fed by two very busy parents. Do you love birds? Newhaven Wildlife Sanctuary has a huge diversity of habitats and is a renowned arid zone bird watching destination, supporting over 170 species – head up there for a visit, it’s well worth it!

 

Red-capped Robin juvenile

Red-capped Robin juvenile

 

Red-capped Robin female with food for her young

Red-capped Robin female with food for her young

 

Red-capped Robin male defending his territory

Red-capped Robin male defending his territory

Keep an Eye to the Sky: Nesting White-Plumed Honeyeaters

A bougainvillea in my yard has been home to some breeding White-plumed Honeyeaters (Lichenostomus penicillatus) over the last couple of weeks. The nest is a delicate hanging cup made of grasses and spider web, lined with miscellaneous fur. I only discovered them when they were a few days old and in a little over a week they left the nest, sitting about right with the 14 day nestling period. The parents had kept things quiet over the incubation period (also 14 days) but as the chicks approached their fledging time they made an absolute racket (despite attempts by the parents to pipe them down). This attracted a lot of attention from a Black-faced Cuckoo-shrike (Coracina novaehollandiae), but the parents defended the nest with vigour and the offending visitor got a few blows to the head before retreating to a safe distance. The parents were kept busy with regular feeding intervals, searching high and low for new sources of food to satiate the young ones. The two chicks left the nest a day apart and stayed nearby in a Ghost Gum while they strengthened their wings. Now they are off and exploring their new world!

This week is an eventful one in the bird world, with plenty of activities taking place for the Red Centre Bird Festival – Check out the  Program to see how you can get involved!

 

White-plumed Honeyeaters at approximately 4 days old

White-plumed Honeyeaters at approximately 4 days old

 

White-plumed Honeyeaters at approximately 13 days old

White-plumed Honeyeaters at approximately 13 days old

 

White-plumed Honeyeater adult guarding the nest

White-plumed Honeyeater adult guarding the nest

 

Black-faced Cuckoo-shrike retreating after getting too close to a White-plumed Honeyeater nest

Black-faced Cuckoo-shrike retreating after getting too close to a White-plumed Honeyeater nest

 

Ntaria Junior Rangers

The Land for Wildlife coordinator, Caragh, made the trip to Ntaria / Hermannsburg to help with the Junior Ranger program. With the assistance of the Tjuwanpa Women’s Rangers and Gerard Lessels, LfW helped the Ntaria Junior Rangers understand birds’ nests. The Junior Rangers learned about bird nest design, material use, nest shape and the consequences of nest site selection choices. Some local examples of birds’ nests were used to explain the multiple functions of a nest. They also heard about the Cuckoo – a bird that doesn’t build its own nest at all, but rather places sneaky eggs in the nest of other birds. The Junior Rangers suggested some animals other than birds that make nests, such as ants. To get creative, the Junior Rangers enthusiastically built their own nests, using materials in the nearby area, to explore the role of different materials in nest design and function. What a clever and inventive group of young minds!

Junior Rangers

Junior RangersJunior Rangers

Junior Rangers

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Junior Rangers

Junior Rangers

In other Junior Ranger news, Parks and Wildlife Commission of the Northern Territory are seeking interest for their Junior Ranger program in Alice Springs. This year they will be investigating the Central Australian bush, practicing their Mad Scientist skills, learning all about plants and animals, finding out what makes them tick as they interact with nature. They will also be bushwalking, map reading, tracking, camping, spotlighting and generally having an excellent time! If you know anyone aged 9-12, get their parents to contact Susie Armes (susie.armes@nt.gov.au) as soon as possible to secure a position.

The structural and thermal properties of avian cup-shaped nests

Rangeland Biology and Ecology Seminars

April 29, Friday, 3.30pm at Charles Darwin University, Lecture Theatre HE, Alice Springs *

The structural and thermal properties of avian cup-shaped nests

Dr Caragh Heenan

Land for Wildlife Coordinator, Low Ecological Services P/L, Alice Springs

SHE Nest

Incubation in birds is energetically demanding and the energy invested to maintain egg temperature can influence the outcome of a reproductive event and therefore the lifetime reproductive success of individuals. It is reasonable that heat loss can be minimised by optimising the physical structure and location of the nest. I assessed the structural and thermal properties of nests across 36 species of Australian passerines, assessing variables against parent mass, egg and clutch size, once accounting for phylogenetic relationships. The surface area and volume of the nest cup increases with the surface area and volume of the clutch, as well as the size of the incubating parent. Structural support for the parent and clutch is the primary factor driving nest thickness. A change in nest thickness with the combined mass of the parent and clutch has a direct influence on the conductance of nests, such that structurally adequate nests achieve a lower thermal conductance (higher insulation) than expected, as they increase in size. When exposed to wind or rain, the rate of heat loss from the nest increases, which is likely to have direct consequences on the energetics of the incubating parent. However, birds breeding in warm and wet conditions select materials for nest construction that have a high thermal conductivity to facilitate the nest drying process through rapid evaporation and reduce the overall cost of incubation. This provides confirmation that selecting a sheltered nest site and constructing an appropriate nest to minimise heat loss is important for avian reproductive success.

* Directions: Take the second CDU entrance along Grevillia Drive next to the childcare centre (not the main Centralian college entrance), and go past the old CDU plant nursery. The HE building is straight ahead on the left next to the grape vines and in front of the oval. There is parking in front of the building. The lecture theatre is on the ground floor just inside the doors to the right. Alternate entry to the room for late arrivals is upstairs into the back of the room.